Alien Minds Part III: The Octopus’s Garden and the Country of the Blind

METI logo
The logo of the METI International Puerto Rico workshop. At the center is Charles Darwin, the nineteenth century British naturalist whose theory of evolution is central to assessing the likelihood and nature of extraterrestrial intelligence. To the left is the octopus, a creature that evolved sophisticated cognition and perception along an evolutionary path quite different from that of humans. To the right is the peacock, whose elaborate tail feathers evolved by sexual selection, a process that may also have been of central importance to the evolution of human intelligence. METI International, used with permisson.

In our galaxy, there may be, at least, tens of billions of habitable planets, with conditions suitable for liquid water on their surfaces. There may be habitable moons as well. On an unknown number of those worlds, life may have arisen. On an unknown fraction of life-bearing worlds, life may have evolved into complex multicellular, sexually reproducing forms.

During its habitable period, a world with complex life might produce hundreds of millions of evolutionary lineages. One or a few of them might fortuitously encounter special circumstances that triggered runaway growth of their intelligence. These favored few, if they exist, might have built technological civilizations capable of signaling their presence across interstellar distances, or detecting and deciphering a message we send their way. What might such alien minds be like? What senses might they use? How might we communicate with them?

METI International
METI International

The purposes of the newly created METI (Messaging to ExtraTerrestrial Intelligence) International include fostering multidisciplinary research in the design and transmission of interstellar messages, and building a global community of scholars from the natural sciences, social sciences, humanities, and arts concerned with the origin, distribution, and future of life in the universe.

On May 18 the organization sponsored a workshop which included presentations by biologists, psychologists, cognitive scientists, and linguists. This is the third and final installment of a series of articles about the workshop.

In previous installments, we’ve discussed some ideas about the evolution of intelligence that were featured at the workshop. Here we’ll see whether our Earthly experience can provide us with any clues about how we might communicate with aliens.

Many of the animals that we are most familiar with from daily life, like humans, cats, dogs, birds, fishes, and frogs are vertebrates, or animals with backbones. They are all descended from a common ancestor and share a nervous system organized according to the same basic plan.

Molluscs are another major group of animals that have been evolving separately from vertebrates for more than 600 million years. Although most molluscs, like slugs, snails, and shellfish, have fairly simple nervous systems, one group; the cephalopods, have evolved a much more sophisticated one.

the common octopus
The common octopus, Octopus vulgaris, Is a cephalopod mollusc, has evolved sophisticated cognition and perception along a very different evolutionary path than have human beings and our relatives. The brain is located between the eyes. The large bulbous structure below the eyes is the mantle, a muscular organ involved in swimming. Public domain.

Cephalopods include octopuses, squids, and cuttlefishes. They show cognitive and perceptual abilities rivaling those of our close vertebrate kin. Since this nervous system has a different evolutionary history than of the vertebrates, it is organized in a way completely different from our own. It can give us a glimpse of the similarities and differences we might expect between aliens and ourselves.

David Gire, an associate professor of psychology at the University of Washington, and researcher Dominic Sivitilli gave a presentation on cephalopods at the Puerto Rico workshop. Although these animals have a sophisticated brain, their nervous systems are much more decentralized than that of familiar animals. In the octopus, sensing and moving are controlled locally in the arms, which together contain as many nerve cells, or neurons, as the brain.

David Gire
Dr. David Gire is an Assistant Professor in the Department of Psychology at the University of Washington and a behavioral neuroscientist. He presented at the Puerto Rico workshop on cephalopod intelligence.

The animal’s eight arms are extraordinarily sensitive. Each containing hundreds of suckers, with thousands of sensory receptors on each one. By comparison, the human finger has only 241 sensory receptors per square centimeter. Many of these receptors sense chemicals, corresponding roughly to our senses of taste and smell. Much of this sensory information is processed locally in the arms. When an arm is severed from an octopus’s body, it continues to show simple behaviors on its own, and can even avoid threats. The octopus’s brain simply acts to coordinate the behaviors of its arms.

Cephalopods have acute vision. Although their eyes evolved separately from those of vertebrates, they nonetheless bear an eerie resemblance. They have a unique ability to change the pattern and color of their skin using pigment cells that are under direct control of their nervous systems. This provides them with the most sophisticated camouflage system of any animal on Earth, and is also used for social signaling.

Despite the sophisticated cognitive abilities it exhibits in the lab, the octopus is largely solitary.
Cephalopod groups exchange useful information by observing one another, but otherwise exhibit only limited social cooperation. Many current theories of the evolution of sophisticated intelligence, like Miller’s sapiosexual hypothesis, which was featured in the second installment, assume that social cooperation and competition play a central role in the evolution of complicated brains. Since cephalopods have evolved much more impressive cognitive abilities than other molluscs, their limited social behavior is surprising.

Dominic Sivitilli
Dominic Sivitilli is a post-baccalaureate researcher in the laboratory of David Gire, studying responses to chemical signals by the octopus. He is the co-presenter of a talk on cephalopod cogntition at the METI International Puerto Rico conference. METI International used with permission.

Maybe the limited social behavior of cephalopods really does set limits on their intelligence. However, Gire and Sivitilli speculate that perhaps “an intelligence capable of technological development could exist with minimum social acuity”, and the cephalopod ability to socially share information is enough. The individuals of such an alien collective, they suppose, might possess no sense of self or other.

Besides Gire and Sivitilli, Anna Dornhaus, whose ideas were featured in the first installment, also thinks that alien creatures might function together as a collective mind. Social insects, in some respects, actually do. She doubts, though, that such an entities could evolve human-like technological intelligence without something like Miller’s sapiosexuality to trigger a runaway explosion of intelligence.

But if non-sapiosexual alien technological civilizations do exist, we might find them impossible to comprehend. Given this possible gulf of incomprehension about social structure, Gire and Stivitilli suppose that the most we might aspire to accomplish in terms of interstellar communication is an exchange of mutually useful and comprehensible astronomical information.

Workshop presenter Alfred Kracher, a retired staff scientist at the Ames Laboratory of the University of Iowa, supposes that “the mental giants of the Milky Way are probably artificially intelligent machines… It would be interesting to find evidence of them, if they exist”, he writes, “but then what?” Kracher supposes that if they have emancipated themselves and evolved away from their makers, “they will have nothing in common with organic life forms, human or extraterrestrial. There is no chance of mutual understanding”. We will be able to understand aliens, he maintains, only if “it turns out that the evolution of extraterrestrial life forms is highly convergent with our own”.

Peter Todd, a professor of psychology from Indiana University, holds out hope that such convergence may actually occur. Earthly animals must solve a variety of basic problems that are presented by the physical and biological world that they inhabit.

They must effectively navigate through a world of surfaces, barriers and objects, finding food and shelter, and avoiding predators, parasites, toxins. Extraterrestrial organisms, if they evolve in an Earth-like environment, would face a generally similar set of problems. They may well arrive at similar solutions, just as the octopus evolved eyes similar to ours.

In evolution here on Earth, Todd notes, brain systems originally evolved to solve these basic physical and biological problems appear to have been re-purposed to solve new and more difficult problems, as some animals evolved to solve the problems of living and finding mates as members of societies, and then as one particular ape species went on to evolve conceptual reasoning and language. For example, disgust at bad food, useful for avoiding disease, may have been become the foundation for sexual disgust to avoid bad mates, moral disgust to avoid bad clan mates, and intellectual disgust to avoid dubious ideas.

If alien brains evolved solutions similar to the ones our brains did for negotiating the physical and biological world, they they might also have been re-purposed in similar ways. Alien minds might not be wholly different from ours, and thus hope exists for a degree of mutual understanding.

In the early 1970’s the Pioneer 10 and 11 spacecraft were launched on the first exploratory missions to the planet Jupiter and beyond. When their missions were completed, these two probes became the first objects made by humans to escape the sun’s gravitational pull and hurtle into interstellar space.

Because of the remote possibility that the spacecraft might someday be found by extraterrestrials, a team of scientists and scholars lead by Carl Sagan emplaced a message on the vehicle, etched on a metal plaque. The message consisted, in part, of a line drawing of a man and a woman. Later, the Voyager 1 and 2 spacecraft carried a message that consisted, in part, of a series of 116 digital images encoded on a phonographic record.

Use of images in interstellar messages
The use of images in interstellar communication. In 1977, NASA launched the Voyager 1 and 2 spacecraft on a mission to explore the outer solar system. Destined to wander interstellar space forever following the completion of their mission, each spacecraft carried an interstellar message encoded on a phonographic record. The message, designed by SETI pioneers Carl Sagan and Frank Drake and their collaborators, included 116 digital images. This image is intended to show extraterrestrials how human beings eat and drink. Will extraterrestrials understand such images? The limited quality of the image reflects the state of digital imaging technology in the 70’s National Astronomy and Ionosphere Center, public domain.

The assumption that aliens would see and understand images seems reasonable, since the octopus evolved an eye so similar to our own. And that’s not all. The evolutionary biologists Luitfried Von Salvini-Plawen and Ernst Mayr showed that eyes, of various sorts, have evolved forty separate times on Earth, and vision is typically a dominant sense for large, land dwelling animals. Still, there are animals that function without it, and our earliest mammalian ancestors were nocturnal. Could it be that there are aliens that lack vision, and could not understand a message based on images?

In his short story, The Country of the Blind, the great science fiction writer H. G. Wells imagined an isolated mountain village whose inhabitants had been blind for fifteen generations after a disease destroyed their vision.

A lost mountain climber, finding the village, imagines that with his power of vision, he can easily become their king. But the villagers have adapted thoroughly to a life based on touch, hearing, and smell. Instead of being impressed by their visitor’s claim that he can ‘see’, they find it incomprehensible. They begin to believe he is insane. And when they seek to ‘cure’ him by removing two strange globular growths from the front of his head, he flees.

Mexican blind cavefish
The Mexican blind cavefish (Astyanax mexicanus) has lived in the total darkness of a cave system in central Mexico for more than a million years, and has evolved the loss of its eyes. Astyanax possess a sense that land dwelling animals lack. The lateral line sense, which is present in all fishes, allows these animals to sense their near surroundings based on pressure differences in fields of water flow around their bodies. They also have an acute sense of taste, with taste receptors on their bodies as well as in their mouths. The evolution of cave dwelling intelligent life is probably unlikely, since large brains are metabolically expensive, and food is scarce in caves. On the surface, plants capture energy from sunlight and form the base of the food chain. State Museum of Natural History, Karlsruhe.

Could their really be an alien country of the blind whose inhabitants function without vision? Workshop presenter Dr. Sheri Wells-Jensen, an associate professor of Linguistics at Bowling Green State University, doesn’t need to imagine the country of the blind, because, in a sense, she lives there. She is blind, and believes that creatures without vision could achieve a level of technology sufficient to send interstellar messages. “Sighted people”, she writes, “tend to overestimate the amount and quality of information gathered by vision alone”.
Sheri Wells Jensen
Dr. Sheri Wells-Jensen is an associate professor of linguistics at Bowling Green State University. She presented at talk at the Puerto Rico workshop on alternative perceptual systems and interstellar communications. METI International, used with permission.

Bats and dolphins image their dimly lit environments with a kind of naturally occurring sonar called echolocation. Blind human beings can also learn to echolocate, using tongue clicks or claps as emitted signals and analyzing the returning echoes by hearing. Some can do so well enough to ride a bicycle at a moderate pace through an unfamiliar neighborhood. A human can develop the touch sensitivity needed to read braille in four months. A blind marine biologist can proficiently distinguish the species of mollusc shells by touch.

Wells-Jensen posits a hypothetical civilization which she calls the Krikkits, who lack vision but possess sensory abilities otherwise similar to those of human beings. Could such beings build a technological society? Drawing on her knowledge of the blind community and a series of experiments, she thinks they could.

Finding food would present few special difficulties, since blind naturalists can identify many plant species by touch. Agriculture could be conducted as modern blind gardeners do it, by marking crops using stakes and piles of rock, and harvesting by feel. The combination of a stick used as a cane to probe the path ahead and echolocation make traveling by foot effective and safe. A loadstone compass would further aid navigational abilities. The Krikkits might use snares rather than spears or arrows to trap animals, making tools by touch.

Mathematics is vital to building a technological society. For most human beings, with our limited memory, a paper and pencil or a blackboard are essential for doing math. Krikkits would need to find other such aids, such as tactual symbols on clay tablets, abacus-like devices, or patterns sewn on hides or fabric.

Successful blind mathematicians often have prodigious memories, and can perform complex calculations in their heads. One of history’s greatest mathematicians, Leonard Euler, was blind for the last 17 years of his life, but remained mathematically productive through the use of his memory.

The obstacles to a blind society developing technology may not be insurmountable. Blind people are capable of handling fire and even working with molten glass. Krikkits might therefore use fire for cooking, warmth, to bake clay vessels, and smelt metal ores. Initially there only astronomical knowledge would be of the sun as a source of heat. Experiments with loadstones and metals would lead to a knowledge of electricity.

Eventually, the Krikkits might imitate their sonar with radio waves, inventing radar. If their planet possessed a moon or moons, radar reflections from them might provide their first knowledge of astronomical objects other than their sun. Radar would also enable them to learn for the first time that their planet is round.

The Krikkits might learn to detect other forms of radiation like X-rays and ‘light’. The ability to detect this second mysterious form of radiation might allow them to discover the existence of the stars and develop an interest in interstellar communication.

What sorts of messages might they send or understand? Well-Jensen believes that line drawings, like the drawing of the man and the woman on the Pioneer plaque, and other such pictorial representations might be an impenetrable mystery to them. On the other hand, she speculates that Krikkits might represent large data sets through sound, and that their counterpart to charts and graphs might be equally incomprehensible to us.

Images might pose a challenge for the Krikkits, but perhaps, Wells-Jensen concedes, not an impossible one. There is evidence that bats image their world using echolocation. Kikkits might be likely to evolve similar abilities, though Wells-Jensen believes they would not be essential for making tools or handling objects.

Perhaps humans and Krikkits could find common ground by transmitting instructions for three dimensional printed objects that could be explored tactually. Wells-Jensen thinks they might also understand mathematical or logical languages proposed for interstellar communication.

The diversity of cognition and perception that we find here on Earth teaches us that if extraterrestrial intelligence exists, it is likely to be much more alien than much of science fiction has prepared us to expect. In our attempt to communicate with aliens, the gulf of mutual incomprehension may yawn as wide as the gulf of interstellar space. Yet this is a gulf we must somehow cross, if we wish ever to become citizens of the galaxy.

For further reading:

Cain, F. (2008) Is Our Universe Ruled by Artificial Intelligence, Universe Today.

Kaufmann G. (2005) Spineless smarts, NOVA

Land, M. F., and Nilsson, D-E. (2002) Animal Eyes, Oxford University Press.

Mather, J. A. (2008) Cephalopod consciousness: Behavioral evidence, Cognition and Consciousness 17(1): 37-48.

Patton, P. E. (2016) Alien Minds I: Are Extraterrestrial Civilizations Likely to Evolve? Universe Today.

Patton, P. E. (2016) Alien Minds II: Do Aliens Think Big Brains are Sexy Too? Universe Today.

P. Patton (2014) Communicating across the cosmos, Part 1: Shouting into the darkness, Part 2: Petabytes from the Stars, Part 3: Bridging the Vast Gulf, Part 4: Quest for a Rosetta Stone, Universe Today.

Wells, H. G. (1904) The Country of the Blind, The literature network.

Alien Minds Part II: Do Aliens Think Big Brains are Sexy Too?

peahen and peacock
The peahen (at left) and the peacock (at right). The peacock’s elaborate plumage and many other similar animal ornaments posed a troubling difficulty for Charles Darwin in his development of the theory of evolution, since they seemed to have no value for survival. The peacocks that were everywhere present in English gardens were a frustrating and ever-present reminder of the difficulty. “The sight of a feather in a peacock’s tail”, Darwin wrote, “whenever I gaze at it, makes me sick!”. Darwin solved the problem with his theory of sexual selection, which posits that such ornaments evolved because they help animals to woo mates, and thereby pass the trait into the next generation. Since mating in peafowl is by female choice, elaborate tail feathers are vital to the peacock, but unnecessary to the peahen. Sexual selection is increasingly recognized as a central evolutionary process by modern biologists. Evolutionary psychologist Dr. Geoffrey Miller posits that the enormous human brain evolved by sexual selection through the choices of both genders. Understanding how human intelligence evolved here on Earth is critical to understanding whether or not alien civilizations are likely to exist. Picture is from the Miho Museum, Shiga, Japan, 1781, public domain.

“Nothing in biology makes sense”, wrote the evolutionary biologist Theodosius Dobzhansky, “except in the light of evolution”. If we want to assess whether it is likely that technological civilizations have evolved on alien planets or moons, and what they might be like, the theory of evolution is our best guide. On May 18, 2016 the newly founded METI (Messaging to ExtraTerrestrial Intelligence) International hosted a workshop entitled ‘The Intelligence of SETI: Cognition and Communication in Extraterrestrial Intelligence’. The workshop was held in San Juan, Puerto Rico on the first day of the National Space Society’s International Space Development Conference. It included nine talks by scientists and scholars in evolutionary biology, psychology, cognitive science, and linguistics.

METI International
METI International

In the first instalment of this series, we saw that intelligence, of various sorts, is widespread across the animal kingdom. Workshop presenter Anna Dornhaus, who studies collective decision-making in insects as an associate professor at the University of Arizona, showed that even insects, with their diminutive brains, exhibit a surprising cognitive sophistication. Intelligence, of various sorts, is a likely and probable evolutionary product.

Animals evolve the cognitive abilities that they need to meet the demands of their own particular environments and lifestyles. Sophisticated brains and cognition have evolved many times on Earth, in many separate evolutionary lineages. But, of the millions of evolutionary lineages that have arisen on Earth in the 600 million years since complex life appeared, only one, that which led to human beings, produced the peculiar combination of cognitive traits that led to a technological civilization. What this tells us is that technological civilization is not the inevitable product of a long term evolutionary trend, it is rather the quirky and contingent product of particular circumstances. But what might those circumstances have been, and just how special and improbable were they?

Geoffrey Miller
Dr. Geoffery Miller is an associate professor of psychology at the University of New Mexico, and is the author of a 2001 book, The Mating Mind, where he explains his theory that human intelligence evolved by sexual selection to a general audience. He presented at the METI Institute conference in Puerto Rico, in May 2016. Picture used with permission.

Workshop presenter Geoffrey Miller is an associate professor of psychology at the University of New Mexico. Miller thinks he has an answer to the question of what the special circumstances that produced human evolution were. Our protohuman ancestors inhabited the African savanna. But so do many other mammals that don’t need enormous brains to survive there. The evolutionary forces driving the production of our large brains, Miller surmises, can’t be due to the challenges of survival. He thinks instead that human evolution was guided by an intelligence. But Miller is no creationist, nor does he have the alien monolith from the 1960’s science fiction classic 2001: A Space Odyssey in mind. Miller’s guiding intelligence is the intelligence that our ancestors themselves used when they selected their mates.

Miller’s theory harkens back to the ideas of the founder of modern evolutionary theory, the nineteenth century British naturalist Charles Darwin. Darwin proposed that evolution works through a process of natural selection. Animal offspring vary one from another, and are produced in too great of numbers for all of them to survive. Some starve, some are eaten by predators, others fall prey to the numerous other hazards of the natural world. A few survive to produce offspring, thereby passing on the traits that allowed them to survive. Down the generations, traits that aided survival become more elaborate and useful and traits that did not, vanished.

Charles Darwin
Charles Darwin published his theory of evolution, in his book, The Origin of Species, in 1859. The theory was inspired, in part, by observations he made during his five year voyage as a naturalist on board the HMS Beagle and has become the central principle of much of modern biology. Picture by George Richmond (1830’s) public domain.

But Darwin was troubled by a serious problem with his theory. He knew that many animals have prominent traits that don’t seem to contribute to their survival, and are even counterproductive to it. The bright colors of many insects, the colors, elaborate plumage, and songs of birds, the huge antlers of elk, were all prominent and costly traits that couldn’t be explained by his theory of natural selection. Peacocks, with their elaborate tail feathers were everywhere in English gardens, and came to torment him.

At last, Darwin found the solution. To produce offspring, an animal must do more than just survive, it must find a partner to mate with. All the traits which worried Darwin could be explained if they served to make their bearers sexier and more beautiful to prospective mates than other competing members of their own gender. If peahens like elaborate plumage, then in each generation, they will choose to mate with the males with the most elaborate tail feathers, and reject the rest. Through the competition for mates, peacock tails will become more and more elaborate down the generations. Darwin called his new theory sexual selection.

Many subsequent evolutionary biologists regarded sexual selection as of limited importance, and lumped it in with natural selection, which was said to favor traits conducive to survival and reproductive success. However, in recent decades evolutionary biologists have come to view sexual selection in a much more favorable light. Geoffrey Miller proposed that the human brain evolved through sexual selection. Human beings, he supposes, are sapiosexual; that is, they are sexually attracted by intelligence and its products. The preference for selecting intelligent mates produced greater intelligence, which in turn allowed our ancestors to become more discerning in selecting more intelligent mates, producing a kind of amplifying feedback loop, and an explosion of intelligence.

On this account, language, music, dancing, humor, art, literature, and perhaps even morality and ethics exist because those who were good at them were deemed sexier, or more trustworthy and reliable, and were thus more successful in securing mates than those who weren’t. The elaborate human brain is like the elaborate peacock’s tail. It exists for wooing mates and not for survival. There are some important ways in which protohumans were different from peafowl. Both males and females are choosy and both have large brains. Protohumans, unlike peafowl, probably formed monogamous pair bonds. Miller’s theory has complexities that space won’t permit us to explore here. To show that his theory can work, Miller needed to develop a computer model.

Human evolution
The evolution of protohuman intelligence through geography and time. Homo egaster lived in the early Pleistocene between 1.9 and 1.4 million years ago and had a brain about half the size of modern Homo sapiens. It developed advanced stone tools, and may have domesticated fire. It was closely related to Homo erectus. Homo antecessor lived from 1.2 million to 800,000 years ago and spread from Africa into Europe. It’s brain was also about half as large as that of ours. Homo rhodesiensis lived about 120,000 to 300,000 years ago. Our species, Homo sapiens, arose in Africa about 200,000 years ago and spread throughout much of the world. Homo neanderthalensis had a brain capacity somewhat larger than that of modern humans, and its larger eye sockets suggest keener vision. They disappeared about 30,000 years ago, and may have died out, in part, through competition with Homo sapiens and cooling of the climate. Public Library of Science 2003.

If Miller is right, then just how probable is the evolution of a technological civilization, and how likely is it that we will find them elsewhere in the galaxy? Miller thinks that if complex life exists on other planets or moons, it is likely to evolve reproduction through sex, just as has happened here on Earth. For complex organisms that depend on a large and complicated body of genetic information, most mutations will be neutral or harmful. In sexual reproduction half the genes of one’s offspring come from each parent. Without this mixing of genes from other individuals, asexual lineages are likely to falter and go extinct due to an accumulation of harmful mutations. Unless sexually reproducing creatures choose their mates purely at random, sexual selection is an inevitability. So, the basic conditions for runaway sexual selection to produce a brain suited to language and technology probably exists on other worlds with complex life.

One problem, though, that Anna Dornhaus pointed out, is that in sexual selection, the trait that gets exaggerated is essentially arbitrary. There are many bird species with elaborate plumage, but none exactly like the peacock. There are many species where brains and cognitive traits matter for mating success, like the singing ability of nightingales and many other birds, or gibbons, or whales. Male bower birds build complicated structures, called bowers, out of found items, like sticks and leaves and stones and shells, to attract a female. Chimpanzees engage in complex power struggles that involve negotiation, grooming, and fighting their way to the top.

But despite the selective success of cognition and braininess in many species, our specific human sort of intelligence, with language and technology, has happened only once on Earth, and therefore might be rare in the universe. If our ancestors had found big noses rather than big brains sexy, then we might now have enormous noses rather than enormous radio telescopes capable of signaling to other worlds.

Miller is more optimistic. “It’s a rare accident” he writes, in the sense that mate preferences only rarely turn ‘sapiosexual’, focused so heavily on conspicuous displays of general intelligence… On the other hand, I think it’s likely that in any biosphere, sexual selection would eventually stumble into sapiosexual mate preferences, and then you’d get human-level intelligence and language of some sort. It might only arise in 1 out of every 100 million species though,…I suspect that in any biosphere with sexually reproducing complex organisms and a wide variety of species, you’d quite likely get at least one lineage stumbling into the sapiosexual niche within a billion years”.

A planet or moon is currently deemed potentially habitable if it orbits its parent star within the right distance range for liquid water to exist on its surface. This distance range is called the habitable zone. Since stars evolve with time, the duration of habitability is limited. Such matters can be explored through climate modeling, informed by what we know of the climates of Earth and other worlds within our solar system, and about the evolution of stars.

Current thinking is that Earth’s total duration of habitability is 6.3 to 7.8 billion years, and that our world may remain habitable for another 1.75 billion years. Since complex life has already existed on Earth for 600 million years, this seems a generous amount of time for complex life on a similar planet to stumble upon Miller’s sapiosexual niche. Stars of smaller mass than the sun are stable on longer timescales, some perhaps capable of sustaining worlds with liquid water for a hundred billion years. If Miller’s estimates are reasonable, then there may be worlds enough and time for an abundance of sapiosexual alien civilizations in our galaxy.

A central message of the METI Institute workshop is that, animals evolve whatever sort of intelligence is necessary for them to survive and reproduce under the circumstances in which they find themselves. Human-style intelligence, with language and technology, is a peculiar quirk of particular and improbable evolutionary circumstances. But we don’t know just how improbable. Given the vastness of time and number of worlds potentially available for the roll of the evolutionary dice, alien civilizations might be reasonably abundant, or they might be once-in-a-billion galaxies rare. We just don’t know. Better knowledge of the evolution of life and intelligence here on Earth might allow us to improve our estimates.

If alien civilizations do exist, what can life on Earth tell us about what their minds and senses are likely to be like? Are they, like us, visually oriented creatures, or might they rely on other senses? Can we expect that their minds might be similar enough to ours to make meaningful communication possible? These intriguing questions will be the subject of the third and final installment of this series.

For further reading:

Hooper, P. L. (2008) Mutual mate choice can drive costly signalling even under perfect monogamy. Adaptive Behavior, 16: p. 53-70.

Marris, E. (2013) Earth’s days are numbered. Nature News.

Miller, G. F. (2000) The Mating Mind: How Sexual Choice Shaped the Evolution of Human Nature. Random House, New York.

Miller, G. F. (2007) Sexual selection for moral virtues, The Quarterly Review of Biology, 82(2): p. 97-125.

Patton, P. E. (2016) Alien Minds I: Are Extraterrestrial Civilizations Likely to Evolve? Universe Today.

P. Patton (2014) Communicating across the cosmos, Part 1: Shouting into the darkness, Part 2: Petabytes from the Stars, Part 3: Bridging the Vast Gulf, Part 4: Quest for a Rosetta Stone, Universe Today.

Rushby, A. J., Claire, M. W., Osborn, H., Watson, A. J. (2013) Habitable zone lifetimes of exoplanets around main sequence stars. Astrobiology, 13(9), p. 833-849.

Yirka, B. (2016) Yeast study offers evidence of the superiority of sexual reproduction versus cloning in speed of adaptation. Phys.org.

Alien Minds I: Are Extraterrestrial Civilizations Likely to Evolve?

The face of a jumping spider
The face of a dimorphic jumping spider (Maevia inclemens). Spiders have a very different evolutionary history from more familiar animals with backbones, and function in a different regime of body sizes. Their sensory endowment is thus evocative of what we might find in aliens. Spiders typically have a total of eight eyes, In this image, four eyes are clearly visible as shiny black globes, and two additional eyes are partially visible around the side of the head. The large frontal eyes provide the acute vision needed to recognize and capture prey. The other eyes provide the spider with a broad field of view, extending even behind the head which allows it to detect a potential meal, and to avoid predators. This image was taken in 2005 by an author named ‘Opoterser’ for open use.

Is it likely that human level intelligence and technological civilization has evolved on other worlds? If so, what kinds of sensory and cognitive systems might extraterrestrials have? This was the subject of the workshop ‘The Intelligence of SETI: Cognition and Communication in Extraterrestrial Intelligence’ held in Puerto Rico on May 18, 2016. The conference was sponsored by the newly founded METI International (Messaging to ExtraTerrestrial Intelligence). One of the organization’s central goals is to build an interdisciplinary community of scholars concerned with designing interstellar messages that can be understood by non-human minds.

METI International
METI International


At present, the only clues we have to the nature of extraterrestrial minds and perception are those that can be garnered by a careful study of the evolution of mind and perception here on Earth. The workshop included nine speakers from universities in the United States and Sweden, specializing in biology, psychology, cognitive science, and linguistics. It had sessions on the evolution of cognition and the likely communicative and cognitive abilities of extraterrestrials.

Doug Vakoch, a psychologist and the founder and president of METI International, notes that astronomers and physicists properly concern themselves largely with the technologies needed to detect alien intelligence. However, finding and successfully communicating with aliens may require attention to the evolution and possible nature of alien intelligence. “The exciting thing about this workshop”, Vakoch writes, “is that the speakers are giving concrete guidelines about how to apply insights from basic research in biology and linguistics to constructing interstellar messages”. In this, the first installment dealing with the conference, we’ll focus on the question of whether the evolution of technological societies on other planets is likely to be common, or rare.

Doug Vakoch, President METI Institute
Dr. Douglas Vakoch is a Professor of clinical psychology and the founder and president of METI International. Photo by Mara Lavitt, used with permission.

We now know that most stars have planets, and rocky planets similar to or somewhat larger than the Earth or Venus are commonplace. Within this abundant class of worlds, there are likely to be tens of billions with conditions suitable for sustaining liquid water on their surfaces in our galaxy. We don’t yet know how likely it is that life will arise on such worlds. But suppose, as many scientists suspect, that simple life is abundant. How likely is it that alien civilizations will appear; civilizations with which we could communicate and exchange ideas, and which could make their presence known to us by signaling into space? This was a central question explored at the conference.

In addressing such questions, scientists have two main sets of clues to draw on. The first comes from the study of the enormous diversity of behavior and nervous and sensory systems of the animal species that inhabit our Earth; an endeavor that has been called cognitive ecology. The second set of clues come from modern biology’s central principle; the theory of evolution. Evolutionary theory can provide scientific explanations of how and why various senses and cognitive systems have come to exist here on Earth, and can guide our expectations about what might exist elsewhere.

Artist's impression of three newly-discovered exoplanets orbiting an ultracool dwarf star TRAPPIST-1. Credit: ESO/M. Kornmesser/N. Risinger (skysurvey.org).
Artist’s impression of three newly-discovered exoplanets orbiting an ultracool dwarf star TRAPPIST-1. Credit: ESO/M. Kornmesser/N. Risinger (skysurvey.org).
The basics of the electrochemical signalling that make animal nervous systems possible have deep evolutionary roots. Even plants and bacteria have electrochemical signalling systems that share some basic features with those in our brains. Conference presenter Dr. Anna Dornhaus studies how social insects make decisions collectively as an associate professor at the University of Arizona. She defines cognitive ability as the ability to solve problems with a nervous system, and sometimes also by social cooperation. An animal is more ‘intelligent’ if its problem solving abilities are more generalized. Defined this way, intelligence is widespread among animals. Skills traditionally thought to be the sole province of primates (monkeys and apes, including human beings) have now been shown to be surprisingly common.
Dr. Anna Dornhaus
Dr. Anna Dornhaus is an Associate Professor of Ecology and Evolutionary Biology at the University of Arizona, and a presenter at the Puerto Rico conference

For example, cognitive skills like social learning and teaching, generalizing from examples, using tools, recognizing individuals of one’s species, making plans, and understanding spatial relationships have all been shown to exist in arthropods (an animal group consisting of insects, spiders, and crustaceans). The evidence shows the surprising power of the diminutive brains of insects, and indicates that we know little of the relationship between brain size and cognitive ability.

But different animals often have different sets of cognitive skills, and if a species is good at one cognitive skill, that doesn’t necessarily mean it will be good at others. Human beings are special, not because we have some specific cognitive ability that other animals lack, but because we possess a wide range of cognitive abilities that are more exaggerated and highly developed than in other animals.

The cathedral termite mound
Termite mounds demonstrate that architecture and agriculture are not unique to humans. Housing one to two million inhabitants, they can reach 5 meters (17 feet) or more in height, and also extend beneath the surface of the ground. They are organized to ensure that appropriate levels of oxygen, moisture, and temperature are maintained. Although the inhabitants of a termite mound collectively weigh only 15 kilograms (33 lb), a typical mound will, in an average year, move a quarter of a metric ton (550 lb) of soil, and several tons of water. Using carefully prepared plant materials, termites “farm” a species of fungus that occupies eight times more space in the mound than they do. Photo taken by Brain Voon Yee Yap of cathedral termite mounds in the Northern Territories of Australia for open use.

Although the Earth, as a planet, has existed for 4.6 billion years, complex animals with hard body parts don’t appear in the fossil record until 600 million years ago, and complex life didn’t appear on land until about 400 million years ago. Looking across the animal kingdom as a whole, three groups of animals, following separate evolutionary paths, have evolved especially complex nervous systems and behaviors. We’ve already mentioned arthropods, and the sophisticated behaviors mediated by their diminutive yet powerful brains.

Molluscs, a group of animals that includes slugs and shellfish, have also produced a group of brainy animals; the cephalopods. The cephalopods include octopuses, squids, and cuttlefish. The octopus has the most complex nervous system of any animal without a backbone. As the product of a different evolutionary path, the octopus’s sophisticated brain has a plan of organization that is completely alien to that of more familiar animals with backbones.

The third group to have produced sophisticated brains are the vertebrates; animals with backbones. They include fishes, amphibians, reptiles, birds, and mammals, including human beings. Although all vertebrate brains bear a family resemblance, complex brains have evolved from simpler brains many separate times along different paths of vertebrate evolution, and each such brain has its own unique characteristics.

Along one path, birds have evolved a sophisticated forebrain, and with it, a flexible and creative capacity to make and use tools, an ability to classify and categorize objects, and even a rudimentary understanding of numbers. Following a different path, and based on a different plan of forebrain organization, mammals have also evolved sophisticated intelligence. Three groups of mammals; elephants, cetaceans (a group of aquatic mammals including dophins, porpoises, and whales), and primates (monkeys and apes, including human beings) have evolved the most complex brains on Earth.

Given the evidence that intelligent problem solving skills of various sorts have evolved many times over, along many different evolutionary pathways, in an amazing range of animal groups, one might suspect that Dornhaus believes that human-style cognitive abilities and civilizations are widespread in the universe. In fact, she doesn’t. She thinks that humans with their exaggerated cognitive abilities and unique ability to use language to express complex and novel sorts of information are a quirky and unusual fluke of evolution, and might, for all we know, be wildly improbable. Her argument that alien civilizations probably aren’t widespread resembles one stated by the imminent and influential American evolutionary biologist Ernst Mayr in his 1988 book Towards a New Philosophy of Biology.

There are currently more than 10 million different species of animals on Earth. All but one have failed to evolve the human level of intelligence. This makes the chance of evolving human intelligence less than one in 10 million. Over the last six hundred million years since complex life has appeared on Earth, there have been tens of million different animal species, each existing for roughly 1-10 million years. But, so far as we know, only one of them, Homo sapiens, ever produced a technological society. The human lineage diverged from that of other great ape species about 8 million years ago, but we don’t see evidence of distinctly human innovation until about 50,000 years ago, which is, perhaps, another indication of its rarity.

Despite the apparent improbability of human level intelligence evolving in any one lineage, Earth, as a whole, with its vast array of evolutionary lineages, has nonetheless produced a technological civilization. But that still doesn’t tell us very much. For the present, Earth is the only habitable planet that we know much of anything about. And, since Earth produced us, we are working with a biased sample. So we can’t be at all confident that the presence of human civilization on Earth implies that similar civilizations are likely to occur elsewhere.

For all we know, the quirky set of events that produced human beings might be so wildly improbable that human civilization is unique in a hundred billion galaxies. But, we don’t know for sure that alien civilizations are wildly improbable either. Dornhaus freely concedes that neither she nor anybody has a good idea of just how improbable human intelligence might be, since the evolution of intelligence is still so poorly understood.

Most current evolutionary thinking, following in the footsteps of Mayr and others, holds that human civilization was not the inevitable product of a long-term evolutionary trend, but rather the quirky consequence of a particular and improbable set of evolutionary events. What sort of events might those have been, and just how improbable were they? Dornhaus supports a popular theory proposed by Dr. Geoffrey Miller, an evolutionary psychologist who is an associate professor in the Department of Psychology at the University of New Mexico and who also spoke at the METI institute workshop.

In our next installment we’ll explore Miller’s theories in a bit more detail, and see why the abundance of extraterrestrial civilizations might depend on whether or not aliens think big brains are sexy.

For further reading:
Baluska, F. and Mancuso, S. (2009) Deep evolutionary origins of neurobiology. Communicative and Integrative Biology, 2:1, 60-65.

Chittka, L. and Niven, J. (2009) Are bigger brains better?, Current Biology. 19:21 p. R995-R1008.

Margonelli, L. (2014) Collective mind in the mound: How do termites build their huge structures. National Geographic.

Mayr, E. (1988) The probability of extraterrestrial intelligent life. In Towards a New Philosophy of Biology, Harvard University Press, Cambridge, MA.

Patton, P. E. (2015) Who speaks for Earth? The controversy over interstellar messaging. Universe Today.

P. Patton (2014) Communicating across the cosmos, Part 1: Shouting into the darkness, Part 2: Petabytes from the Stars, Part 3: Bridging the Vast Gulf, Part 4: Quest for a Rosetta Stone, Universe Today.

Tonn, S. (2015) Termites are teaching architects to design super-efficient skyscrapers. Wired Magazine.

Nearby Supernovas Showered Earth With Iron

Visible, infrared, and X-ray light image of Kepler's supernova remnant (SN 1604) located about 13,000 light-years away. Credit: NASA, ESA, R. Sankrit and W. Blair (Johns Hopkins University).

We all know that we are “made of star-stuff,” with all of the elements necessary for the formation of planets and even life itself having originated inside generations of massive stars, which over billions of years have blasted their creations out into the galaxy at the explosive ends of their lives. Supernovas are some of the most powerful and energetic events in the known Universe, and when a dying star finally explodes you wouldn’t want to be anywhere nearby—fresh elements are nice and all but the energy and radiation from a supernova would roast any planets within tens if not hundreds of light-years in all directions. Luckily for us we’re not in an unsafe range of any supernovas in the foreseeable future, but there was a time geologically not very long ago that these stellar explosions are thought to have occurred in nearby space… and scientists have recently found the “smoking gun” evidence at the bottom of the ocean.

Two independent teams of “deep-sea astronomers”—one led by Dieter Breitschwerdt from the Berlin Institute of Technology and the other by Anton Wallner from the Australian National University—have investigated sediment samples taken from the floors of the Pacific, Atlantic, and Indian oceans. The sediments were found to contain relatively high levels of iron-60, an unstable isotope specifically created during supernovas.

The Local Bubble is a 300-light-year long region that was carved out of the interstellar medium by supernovas (Source: Science@NASA)
The Local Bubble is a 300-light-year long region that was carved out of the interstellar medium by supernovas (Source: Science@NASA)

Watch: How Quickly Does a Supernova Happen?

The teams found that the ages of the iron-60 concentrations (the determination of which was recently perfected by Wallner) centered around two time periods, 1.7 to 3.2 million years ago and 6.5 to 8.7 million years ago. Based on this and the fact that our Solar System currently resides within a peanut-shaped region virtually empty of interstellar gas known as the Local Bubble, the researchers are confident that this provides further evidence that supernovas exploded within a mere 330 light-years of Earth, sending their elemental fallout our way.

“This research essentially proves that certain events happened in the not-too-distant past,” said Adrian Melott, an astrophysicist and professor at the University of Kansas who was not directly involved with the research but published his take on the findings in a letter in Nature. (Source)

The researchers think that two supernova events in particular were responsible for nearly half of the iron-60 concentrations now observed. These are thought to have taken place among a a nearby group of stars known as the Scorpius–Centaurus Association, some 2.3 and 1.5 million years ago. At those same time frames Earth was entering a phase of repeated global glaciation, the end of the last of which led to the rise of modern human civilization.

While supernovas of those sizes and distances wouldn’t have been a direct danger to life here on Earth, could they have played a part in changing the climate?

Read more: Could a Faraway Supernova Threaten Earth?

“Our local research group is working on figuring out what the effects were likely to have been,” Melott said. “We really don’t know. The events weren’t close enough to cause a big mass extinction or severe effects, but not so far away that we can ignore them either. We’re trying to decide if we should expect to have seen any effects on the ground on the Earth.”

Regardless of the correlation, if any, between ice ages and supernovas, it’s important to learn how these events do affect Earth and realize that they may have played an important and perhaps overlooked role in the history of life on our planet.

“Over the past 500 million years there must have been supernovae very nearby with disastrous consequences,” said Melott. “There have been a lot of mass extinctions, but at this point we don’t have enough information to tease out the role of supernovae in them.”

You can find the teams’ papers in Nature here and here.

Sources: IOP PhysicsWorld and the University of Kansas

 

UPDATE 4/14/16: The presence of iron-60 from the same time periods as those mentioned above has also been found on the Moon by research teams in Germany and the U.S. Read more here.

Mars Loses an Ocean But Gains the Potential for Life

NASA scientists have determined that a primitive ocean on Mars held more water than Earth's Arctic Ocean and that the Red Planet has lost 87 percent of that water to space. Credit: NASA/GSFC

It’s hard to believe it now looking at Mars’ dusty, dessicated landscape that it once possessed a vast ocean. A recent NASA study of the Red Planet using the world’s most powerful infrared telescopes clearly indicate a planet that sustained a body of water larger than the Earth’s Arctic Ocean.

If spread evenly across the Martian globe, it would have covered the entire surface to a depth of about 450 feet (137 meters). More likely, the water pooled into the low-lying plains that cover much of Mars’ northern hemisphere. In some places, it would have been nearly a mile (1.6 km) deep. 

Three of the best infrared observatories in the world were used to study normal to heavy water abundances in Mars atmosphere, especially the polar caps, to create a global map of the planet's water content and infer an ancient ocean. Credit: NASA/ GSFC
Three of the best infrared observatories in the world were used to study normal to heavy water abundances in Mars atmosphere, especially the polar caps, to create a global map of the planet’s water content and infer an ancient ocean. Credit: NASA/ GSFC

Now here’s the good part. Before taking flight molecule-by-molecule into space, waves lapped the desert shores for more than 1.5 billion years – longer than the time life needed to develop on Earth. By implication, life had enough time to get kickstarted on Mars, too.

A hydrogen atom is made up of one proton and one electron, but its heavy form, called deuterium, also contains a neutron. HDO or heavy water is rare compared to normal drinking water, but being heavier, more likely to stick around when the lighter form vaporizes into space. Credit: NASA/GFSC
A hydrogen atom is made up of one proton and one electron, but its heavy form, called deuterium, also contains a neutron. HDO or heavy water is rare compared to normal drinking water, but being heavier, more likely to stick around when the lighter form vaporizes into space. Credit: NASA/GFSC

Using the three most powerful infrared telescopes on Earth – the W. M. Keck Observatory in Hawaii, the ESO’s Very Large Telescope and NASA’s Infrared Telescope Facility – scientists at NASA’s Goddard Space Flight Center studied water molecules in the Martian atmosphere. The maps they created show the distribution and amount of two types of water – the normal H2O version we use in our coffee and HDO or heavy water, rare on Earth but not so much on Mars as it turns out.

Maps showing the distribution of H20 and HDO across the planet made with the trio of infrared telescopes. Credit: NASA/GSFC
Maps showing the distribution of H20 and HDO (heavy water) across the planet made with the trio of infrared telescopes. Credit: NASA/GSFC

In heavy water, one of the hydrogen atoms contains a neutron in addition to its lone proton, forming an isotope of hydrogen called deuterium. Because deuterium is more massive than regular hydrogen, heavy water really is heavier than normal water just as its name implies. The new “water maps” showed how the ratio of normal to heavy water varied across the planet according to location and season. Remarkably, the new data show the polar caps, where much of Mars’ current-day water is concentrated, are highly enriched in deuterium.

It's thought that
It’s thought that the decay of Mars’ once-global magnetic field, the solar wind stripped away much of the planet’s early, thicker atmosphere, allowing solar UV light to break water molecules apart. Lighter hydrogen exited into space, concentrating the heavier form. Some of the hydrogen may also departed due to the planet’s weak gravity. Credit: NASA/GSFC

On Earth, the ratio of deuterium to normal hydrogen in water is 1 to 3,200, but at the Mars polar caps it’s 1 to 400.  Normal, lighter hydrogen is slowly lost to space once a small planet has lost its protective atmosphere envelope, concentrating the heavier form of hydrogen. Once scientists knew the deuterium to normal hydrogen ratio, they could directly determine how much water Mars must have had when it was young. The answer is A LOT!

Goddard scientists estimate that only 13% of Mars' original water reserves are still around today, concentrated in the icy polar caps. The rest took off for space. Credit: NASA/GSFC
Goddard scientists estimate that only 13% of Mars’ original water reserves are still around today, concentrated in the icy polar caps. The rest took off for space. Credit: NASA/GSFC

Only 13% of the original water remains on the planet, locked up primarily in the polar regions, while 87% of the original ocean has been lost to space. The most likely place for the ocean would have been the northern plains, a vast, low-elevation region ideal for cupping huge quantities of water. Mars would have been a much more earth-like planet back then with a thicker atmosphere, providing the necessary pressure, and warmer climate to sustain the ocean below.

Mars at the present time has little to no liquid water on its cold, desert-like surface. Long ago, the Sun saw its reflection from wave-rippled lakes and a northern ocean. Credit: NASA/GSFC
Mars at the present time has little to no liquid water on its cold, desert-like surface. Long ago, the Sun almost certainly saw its reflection from wave-rippled lakes and a northern ocean. Credit: NASA/GSFC

What’s most exciting about the findings is that Mars would have stayed wet much longer than originally thought. We know from measurements made by the Curiosity Rover that water flowed on the planet for 1.5 billion years after its formation. But the new study shows that the Mars sloshed with the stuff much longer. Given that the first evidence for life on Earth goes back to 3.5 billion years ago – just a billion years after the planet’s formation – Mars may have had time enough for the evolution of life.

So while we might bemoan the loss of so wonderful a thing as an ocean, we’re left with the tantalizing possibility that it was around long enough to give rise to that most precious of the universe’s creations – life.

To quote Charles Darwin: “… from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.

Illustration showing Mars evolving from a wet world to the present-day Red Planet. Credit: NASA/GSFC
Illustration showing Mars evolving from a wet world to the present-day where liquid water can’t pond on its surface without vaporizing directly into the planet’s thin air. As Mars lost its atmosphere over billions of years, the remaining water, cooled and condensed to form the north and south polar caps. Credit: NASA/GSFC

Defining Life II: Metabolism and Evolution as clues to Extraterrestrial Life

The James Webb Space Telescope, scheduled for launch in 2018 may be the first to be capable of detecting biomarker gasses in the atmospheres of extrasolar planets. When an exoplanet passes between its star and Earth, an event called a transit, light that has passed through the planet’s atmosphere can be detected from a vantage point near Earth. When light passes through the exoplanet’s atmosphere, some wavelengths are absorbed and others transmitted. By analyzing the transmitted light spectrum, astronomers can learn the composition of the planet’s atmosphere. Astrobiologists hope to find biomarker gasses indicating the metabolic waste products of life. The oxygen in Earth’s atmosphere is a waste product of photosynthesis in plants and bacteria. The Webb telescope may be capable of conducting this test for planets larger than Earth (super-earths) transiting small stars. Space telescopes capable of conducting such research on a larger scale have been delayed by budget cuts. Credit: NASA

In the movie “Avatar”, we could tell at a glance that the alien moon Pandora was teeming with alien life. Here on Earth though, the most abundant life is not the plants and animals that we are familiar with. The most abundant life is simple and microscopic. There are 50 million bacterial organisms in a single gram of soil, and the world wide bacterial biomass exceeds that of all plants and animals. Microbes can grow in extreme environments of temperature, salinity, acidity, radiation, and pressure. The most likely form in which we will encounter life elsewhere in our solar system is microbial.

Astrobiologists need strategies for inferring the presence of alien microbial life or its fossilized remains. They need strategies for inferring the presence of alien life on the distant planets of other stars, which are too far away to explore with spacecraft in the foreseeable future. To do these things, they long for a definition of life, that would make it possible to reliably distinguish life from non-life.

Unfortunately, as we saw in the first installment of this series, despite enormous growth in our knowledge of living things, philosophers and scientists have been unable to produce such a definition. Astrobiologists get by as best they can with definitions that are partial, and that have exceptions. Their search is geared to the features of life on Earth, the only life we currently know.

In the first installment, we saw how the composition of terrestrial life influences the search for extraterrestrial life. Astrobiologists search for environments that once contained or currently contain liquid water, and that contain complex molecules based on carbon. Many scientists, however, view the essential features of life as having to do with its capacities instead of its composition.

In 1994, a NASA committee adopted a definition of life as a “self-sustaining chemical system capable of Darwinian evolution”, based on a suggestion by Carl Sagan. This definition contains two features, metabolism and evolution, that are typically mentioned in definitions of life.

Metabolism is the set of chemical processes by which living things actively use energy to maintain themselves, grow, and develop. According to the second law of thermodynamics, a system that doesn’t interact with its external environment will become more disorganized and uniform with time. Living things build and maintain their improbable, highly organized state because they harness sources of energy in their external environment to power their metabolism.

Plants and some bacteria use the energy of sunlight to manufacture larger organic molecules out of simpler subunits. These molecules store chemical energy that can later be extracted by other chemical reactions to power their metabolism. Animals and some bacteria consume plants or other animals as food. They break down complex organic molecules in their food into simpler ones, to extract their stored chemical energy. Some bacteria can use the energy contained in chemicals derived from non-living sources in the process of chemosynthesis.

In a 2014 article in Astrobiology, Lucas John Mix, a Harvard evolutionary biologist, referred to the metabolic definition of life as Haldane Life after the pioneering physiologist J. B. S. Haldane. The Haldane life definition has its problems. Tornadoes and vorticies like Jupiter’s Great Red Spot use environmental energy to sustain their orderly structure, but aren’t alive. Fire uses energy from its environment to sustain itself and grow, but isn’t alive either.

Despite its shortcomings, astrobiologists have used Haldane definition to devise experiments. The Viking Mars landers made the only attempt so far to directly test for extraterrestrial life, by detecting the supposed metabolic activities of Martian microbes. They assumed that Martian metabolism is chemically similar to its terrestrial counterpart.

One experiment sought to detect the metabolic breakdown of nutrients into simpler molecules to extract their energy. A second aimed to detect oxygen as a waste product of photosynthesis. A third tried to show the manufacture of complex organic molecules out of simpler subunits, which also occurs during photosynthesis. All three experiments seemed to give positive results, but many researchers believe that the detailed findings can be explained without biology, by chemical oxidizing agents in the soil.

Viking Lander
In 1976, two Viking spacecraft landed on Mars. The image is of a model of the Viking lander, along with astronomer and pioneering astrobiologist Carl Sagan. Each lander was equipped with life detection experiments designed to detect life based on its metabolic activities. These activities were assumed to be chemically similar to those of Earthly organisms. The three experiments included: 1) The labeled release experiment, in which radioactively labeled organic nutrients were added to Martian soil. If organisms were present, it was assumed that their metabolism would involve breaking down the nutrients for their energy content and releasing labeled carbon dioxide as a waste product. 2) The gas exchange experiment, in which Martian soil was provided with nutrients and light and monitored for the release of oxygen. On Earth, organisms that capture the energy of sunlight through the process of photosynthesis, like plants and some bacteria, release oxygen as a waste product. 3) The pyrolytic release experiment, in which Martian soil was placed in a chamber with radioactively labeled carbon dioxide. If there were organisms in the soil that photosynthesized like those on Earth, their metabolic processes would take up the gas and use the energy of sunlight to manufacture more complex organic molecules. Radioactive carbon would be given off when those more complex molecules were broken down by heating the sample. All three experiments produced what seemed like positive results. However, most scientists rejected this interpretation because the details of many of the results could be explained by supposing that there were chemical oxidizing agents in the soil instead of life, and because Viking failed to detect organic materials in Martian soil. This interpretation, especially for the labeled release experiment, remains controversial to this day and may need to be revisited based on recent findings.
Credits: NASA/Jet Propulsion Laboratory, Caltech

Some of the Viking results remain controversial to this day. At the time, many researchers felt that the failure to find organic materials in Martian soil ruled out a biological interpretation of the metabolic results. The more recent finding that Martian soil actually does contain organic molecules that might have been destroyed by perchlorates during the Viking analysis, and that liquid water was once abundant on the surface of Mars lend new plausibility to the claim that Viking may have actually succeeded in detecting life. By themselves, though, the Viking results didn’t prove that life exists on Mars nor rule it out.

The metabolic activities of life may also leave their mark on the composition of planetary atmospheres. In 2003, the European Mars Express spacecraft detected traces of methane in the Martian atmosphere. In December 2014, a team of NASA scientists reported that the Curiosity Mars rover had confirmed this finding by detected atmospheric methane from the Martian surface.

Most of the methane in Earth’s atmosphere is released by living organisms or their remains. Subterranean bacterial ecosystems that use chemosynthesis as a source of energy are common, and they produce methane as a metabolic waste product. Unfortunately, there are also non-biological geochemical processes that can produce methane. So, once more, Martian methane is frustratingly ambiguous as a sign of life.

Extrasolar planets orbiting other stars are far too distant to visit with spacecraft in the foreseeable future. Astrobiologists still hope to use the Haldane definition to search for life on them. With near future space telescopes, astronomers hope to learn the composition of the atmospheres of these planets by analyzing the spectrum of light wavelengths reflected or transmitted by their atmospheres. The James Webb Space Telescope scheduled for launch in 2018, will be the first to be useful in this project. Astrobiologists want to search for atmospheric biomarkers; gases that are metabolic waste products of living organisms.

Once more, this quest is guided by the only example of a life-bearing planet we currently have; Earth. About 21% of our home planet’s atmosphere is oxygen. This is surprising because oxygen is a highly reactive gas that tends to enter into chemical combinations with other substances. Free oxygen should quickly vanish from our air. It remains present because the loss is constantly being replaced by plants and bacteria that release it as a metabolic waste product of photosynthesis.

Traces of methane are present in Earth’s atmosphere because of chemosynthetic bacteria. Since methane and oxygen react with one another, neither would stay around for long unless living organisms were constantly replenishing the supply. Earth’s atmosphere also contains traces of other gases that are metabolic byproducts.

In general, living things use energy to maintain Earth’s atmosphere in a state far from the thermodynamic equilibrium it would reach without life. Astrobiologists would suspect any planet with an atmosphere in a similar state of harboring life. But, as for the other cases, it would be hard to completely rule out non-biological possibilities.

Besides metabolism, the NASA committee identified evolution as a fundamental ability of living things. For an evolutionary process to occur there must be a group of systems, where each one is capable of reliably reproducing itself. Despite the general reliability of reproduction, there must also be occasional random copying errors in the reproductive process so that the systems come to have differing traits. Finally, the systems must differ in their ability to survive and reproduce based on the benefits or liabilities of their distinctive traits in their environment. When this process is repeated over and over again down the generations, the traits of the systems will become better adapted to their environment. Very complex traits can sometimes evolve in a step-by-step fashion.

Mix named this the Darwin life definition, after the nineteenth century naturalist Charles Darwin, who formulated the theory of evolution. Like the Haldane definition, the Darwin life definition has important shortcomings. It has trouble including everything that we might think of as alive. Mules, for example, can’t reproduce, and so, by this definition, don’t count as being alive.

Despite such shortcomings, the Darwin life definition is critically important, both for scientists studying the origin of life and astrobiologists. The modern version of Darwin’s theory can explain how diverse and complex forms of life can evolve from some initial simple form. A theory of the origin of life is needed to explain how the initial simple form acquired the capacity to evolve in the first place.

The chemical systems or life forms found on other planets or moons in our solar system might be so simple that they are close to the boundary between life and non-life that the Darwin definition establishes. The definition might turn out to be vital to astrobiologists trying to decide whether a chemical system they have found really qualifies as a life form. Biologists still don’t know how life originated. If astrobiologists can find systems near the Darwin boundary, their findings may be pivotally important to understanding the origin of life.

Can astrobiologists use the Darwin definition to find and study extraterrestrial life? It’s unlikely that a visiting spacecraft could detect to process of evolution itself. But, it might be capable of detecting the molecular structures that living organisms need in order to take part in an evolutionary process. Philosopher Mark Bedau has proposed that a minimal system capable of undergoing evolution would need to have three things: 1) a chemical metabolic process, 2) a container, like a cell membrane, to establish the boundaries of the system, and 3) a chemical “program” capable of directing the metabolic activities.

Here on Earth, the chemical program is based on the genetic molecule DNA. Many origin-of-life theorists think that the genetic molecule of the earliest terrestrial life forms may have been the simpler molecule ribonucleic acid (RNA). The genetic program is important to an evolutionary process because it makes the reproductive copying process stable, with only occasional errors.

Both DNA and RNA are biopolymers; long chainlike molecules with many repeating subunits. The specific sequence of nucleotide base subunits in these molecules encodes the genetic information they carry. So that the molecule can encode all possible sequences of genetic information it must be possible for the subunits to occur in any order.

Steven Benner, a computational genomics researcher, believes that we may be able to develop spacecraft experiments to detect alien genetic biopolymers. He notes that DNA and RNA are very unusual biopolymers because changing the sequence in which their subunits occur doesn’t change their chemical properties. It is this unusual property that allows these molecules to be stable carriers of any possible genetic code sequence.

DNA and RNA are both polyelectrolytes; molecules with regularly repeating areas of negative electrical charge. Benner believes that this is what accounts for their remarkable stability. He thinks that any alien genetic biopolymer would also need to be a polyelectrolyte, and that chemical tests could be devised by which a spacecraft might detect such polyelectrolyte molecules. Finding the alien counterpart of DNA is a very exciting prospect, and another piece to the puzzle of identifying alien life.

Structure of DNA
Deoxyribonucleic acid (DNA) is the genetic material for all known life on Earth. DNA is a biopolymer consisting of a string of subunits. The subunits consist of nucleotide base pairs containing a purine (adenine A, or guanine G) and a pyrimidine (thymine T, or cytosine C). DNA can contain nucleotide base pairs in any order without its chemical properties changing. This property is rare in biopolymers, and makes it possible for DNA to encode genetic information in the sequence of its base pairs. This stability is due to the fact that each base pair contains phosphate groups (consisting of phosphorus and oxygen atoms) on the outside with a net negative charge. These repeated negative charges make DNA a polyelectrolyte. Computational genomics researcher Steven Benner has hypothesized that alien genetic material will also be a polyelectrolyte biopolymer, and that chemical tests could therefore be devised to detect alien genetic molecules.
Credit: Zephyris

In 1996 President Clinton, made a dramatic announcement of the possible discovery of life on Mars. Clinton’s speech was motivated by the findings of David McKay’s team with the Alan Hills meteorite. In fact, the McKay findings turned out to be just one piece to the larger puzzle of possible Martian life. Unless an alien someday ambles past our waiting cameras, the question of whether or not extraterrestrial life exists is unlikely to be settled by a single experiment or a sudden dramatic breakthrough. Philosophers and scientists don’t have a single, sure-fire definition of life. Astrobiologists consequently don’t have a single sure-fire test that will settle the issue. If simple forms of life do exist on Mars, or elsewhere in the solar system, it now seems likely that that fact will emerge gradually, based on many converging lines of evidence. We won’t really know what we’re looking for until we find it.

References and further reading:

P. S. Anderson (2011) Could Curiosity Determine if Viking Found Life on Mars?, Universe Today.

S. K. Atreya, P. R. Mahaffy, A-S. Wong, (2007), Methane and related trace species on Mars: Origin, loss, implications for life, and habitability, Planetary and Space Science, 55:358-369.

M. A. Bedau (2010), An Aristotelian account of minimal chemical life, Astrobiology, 10(10): 1011-1020.

S. A. Benner (2010), Defining life, Astrobiology, 10(10):1021-1030.

E. Machery (2012), Why I stopped worrying about the definition of life…and why you should as well, Synthese, 185:145-164.

G. M. Marion, C. H. Fritsen, H. Eicken, M. C. Payne, (2003) The search for life on Europa: Limiting environmental factors, potential habitats, and Earth analogs. Astrobiology 3(4):785-811.

L. J. Mix (2015), Defending definitions of life, Astrobiology, 15(1) posted on-line in advance of publication.

P. E. Patton (2014) Moons of Confusion: Why Finding Extraterrestrial Life may be Harder than we Thought, Universe Today.

T. Reyes (2014) NASA’s Curiosity Rover detects Methane, Organics on Mars, Universe Today.

S. Seeger, M. Schrenk, and W. Bains (2012), An astrophysical view of Earth-based biosignature gases. Astrobiology, 12(1): 61-82.

S. Tirard, M. Morange, and A. Lazcano, (2010), The definition of life: A brief history of an elusive scientific endeavor, Astrobiology, 10(10):1003-1009.

C. R. Webster, and numerous other members of the MSL Science team, (2014) Mars methane detection and variability at Gale crater, Science, Science express early content.

Did Viking Mars landers find life’s building blocks? Missing piece inspires new look at puzzle. Science Daily Featured Research Sept. 5, 2010

NASA rover finds active and ancient organic chemistry on Mars, Jet Propulsion laboratory, California Institute of Technology, News, Dec. 16, 2014.

New Simulation Models Galaxies Like Never Before

Zooming into an EAGLE galaxy. Credit: EAGLE Project Consortium/Schaye et al.

Astronomy is, by definition, intangible. Traditional laboratory-style experiments that utilize variables and control groups are of little use to the scientists who spend their careers analyzing the intricacies our Universe. Instead, astronomers rely on simulations – robust, mathematically-driven facsimiles of the cosmos – to investigate the long-term evolution of objects like stars, black holes, and galaxies. Now, a team of European researchers has broken new ground with their development of the EAGLE project: a simulation that, due to its high level of agreement between theory and observation, can be used to probe the earliest epochs of galaxy formation, over 13 billion years ago.

The EAGLE project, which stands for Evolution and Assembly of GaLaxies and their Environments, owes much of its increased accuracy to the better modeling of galactic winds. Galactic winds are powerful streams of charged particles that “blow” out of galaxies as a result of high-energy processes like star formation, supernova explosions, and the regurgitation of material by active galactic nuclei (the supermassive black holes that lie at the heart of most galaxies). These mighty winds tend to carry gas and dust out of the galaxy, leaving less material for continued star formation and overall growth.

Previous simulations were problematic for researchers because they produced galaxies that were far older and more massive than those that astronomers see today; however, EAGLE’s simulation of strong galactic winds fixes these anomalies. By accounting for characteristic, high-speed ejections of gas and dust over time, researchers found that younger and lighter galaxies naturally emerged.

After running the simulation on two European supercomputers, the Cosmology Machine at Durham University in England and Curie in France, the researchers concluded that the EAGLE project was a success. Indeed, the galaxies produced by EAGLE look just like those that astronomers expect to see when they look to the night sky. Richard Bower, a member of the team from Durham, raved, “The universe generated by the computer is just like the real thing. There are galaxies everywhere, with all the shapes, sizes and colours I’ve seen with the world’s largest telescopes. It is incredible.”

The upshots of this new work are not limited to scientists alone; you, too, can explore the Universe with EAGLE by downloading the team’s Cosmic Universe app. Videos of the EAGLE project’s simulations are also available on the team’s website.

A paper detailing the team’s work is published in the January 1 issue of Monthly Notices of the Royal Astronomical Society. A preprint of the results is available on the ArXiv.

The Origins of Life Could Indeed Be “Interstellar”

This image shows a star-forming region in interstellar space. A new study used AI and radiotelescope data to find 140,000 regions in the Milky Way that will eventually form stars like this region. Image credit: NASA, ESA and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration

Some of science’s most pressing questions involve the origins of life on Earth. How did the first lifeforms emerge from the seemingly hostile conditions that plagued our planet for much of its history? What enabled the leap from simple, unicellular organisms to more complex organisms consisting of many cells working together to metabolize, respire, and reproduce? In such an unfamiliar environment, how does one even separate “life” from non-life in the first place?

Now, scientists at the University of Hawaii at Manoa believe that they may have an answer to at least one of those questions. According to the team, a vital cellular building block called glycerol may have first originated via chemical reactions deep in interstellar space.

Glycerol is an organic molecule that is present in the cell membranes of all living things. In animal cells this membrane takes the form of a phospholipid bilayer, a dual-layer membrane that sandwiches water-repelling fatty acids between outer and inner sheets of water-soluble molecules. This type of membrane allows the cell’s inner aqueous environment to remain separate and protected from its external, similarly watery world. Glycerol is a vital component of each phospholipid because it forms the backbone between the molecule’s two characteristic parts: a polar, water-soluble head, and a non-polar, fatty tail.

Many scientists believe that cell membranes such as these were a necessary prerequisite to the evolution of multicellular life on Earth; however, their complex structure requires a very specific environment – namely, one low in calcium and magnesium salts with a fairly neutral pH and stable temperature. These carefully balanced conditions would have been hard to come by on the prehistoric Earth.

Icy bodies born in interstellar space offer an alternative scenario. Scientists have already discovered organic molecules such as amino acids and lipid precursors in the Murchison meteorite that landed in Australia in 1969. Although the idea remains controversial, it is possible that glycerol could have been brought to Earth in a similar manner.

The Murchison Meteorite. Image credit: James St. John
The Murchison Meteorite.
Image credit: James St. John

Meteors typically form from tiny crumbs of material in cold molecular clouds, regions of gaseous hydrogen and interstellar dust that serve as the birthplace of stars and planetary systems. As they move through the cloud, these grains accumulate layers of frozen water, methanol, carbon dioxide, and carbon monoxide. Over time, high-energy ultraviolet radiation and cosmic rays bombard the icy fragments and cause chemical reactions that enrich their frozen cores with organic compounds. Later, as stars form and ambient material falls into orbit around them, the ices and the organic molecules they contain are incorporated into larger rocky bodies such as meteors. The meteors can then crash into planets like ours, potentially seeding them with building blocks of life.

In order to test whether or not glycerol could be created by the high-energy radiation that typically bombards interstellar ice grains, the team at the University of Hawaii designed their own meteorites: small bits of icy methanol cooled to 5 degrees Kelvin. After blasting their model ices with energetic electrons meant to mimic the effects of cosmic rays, the scientists found that some molecules of methanol within the ices did, in fact, transform into glycerol.

While this experiment appears to be a success, scientists realize that their laboratory models do not exactly replicate conditions in interstellar space. For instance, methanol traditionally makes up only about 30% of the ice in space rocks. Future work will investigate the effects of high-energy radiation on model ices made primarily of water. High-energy electrons fired in a lab are also not a perfect substitute for true cosmic rays and do not represent effects on ice that may result from ultraviolet radiation in interstellar space.

More research is necessary before scientists can draw any global conclusions; however, this study and its predecessors do provide compelling evidence that life as we know it truly could have come from above.

From Eternity to Here: The Amazing Origin of our Species (in 90 Seconds)

From the initial expansion of the Big Bang to the birth of the Moon, from the timid scampering of the first mammals to the rise — and fall — of countless civilizations, this fascinating new video by melodysheep (aka John D. Boswell) takes us on a breathless 90-second tour through human history — starting from the literal beginnings of space and time itself. It’s as imaginative and powerful as the most gripping Hollywood trailer… and it’s even inspired by a true story: ours.

Enjoy!

(Video by melodysheep, creator of the Symphony of Science series.)

Alien Life May Not Be So Alien – If It Exists At All

Our galaxy has exoplanets, organic compounds, liquid water -- even a nebula shaped like a DNA helix -- but is there life? (Image credit: M. Morris/UCLA)

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Are we too hopeful in our hunt for extraterrestrial life? Regardless of exoplanet counts, super-Earths and Goldilocks zones, the probability of life elsewhere in the Universe is still a moot point — to date, we still only know of one instance of it. But even if life does exist somehow, somewhere besides Earth, would it really be all that alien?

In a recent paper titled “Bit by Bit: the Darwinian Basis for Life” Gerald Joyce, Professor of Molecular Biology and Biochemistry at the Scripps Research Institute in La Jolla, CA discusses the nature of life as we know it in regards to its fundamental chemical building blocks — DNA, RNA — and how its ability to pass on the memory of its construction separates true biology from mere chemistry.

“Evolution is nothing more than chemistry plus history,” Joyce said during a Public Library of Science podcast.

The DNA structures that evolved here on Earth — the only place in the Universe we know for certain that life can thrive — have proven to be highly successful (obviously). So what’s to say that life elsewhere wouldn’t be based on the same basic building blocks? And if it is, is it really a “new” life form?

“Truly new ‘alternative life’ would be life of a different biology,” Joyce said. “It would not have the information in it that is part of the same heritage of our life form.”

To arise in the first place, according to Joyce, new life can take two possible routes. Either it begins as chemical connections that grow increasingly more complex until they begin to hold on to the memory of their specific “bit” structure, eventually “bit-flipping” — aka, mutating — into new structures that are either successful or unsuccessful, or it starts from a more “privileged” beginning as an offshoot of previous life, bringing bits into a totally new, immediately successful orientation.

With those two scenarios, anywhere besides Earth “there are no example of either of those conditions so far.”

That’s not saying that there’s no life elsewhere in the Universe… just that we have yet to identify any evidence of it. And without evidence, any discussion of its probability is still pure conjecture.

“In order to estimate probabilities, we need facts,” said Joyce. “The problem is, there is only one life form. And so it’s not possible to estimate probability of life elsewhere when you have only one example.”

Voyager included a golden record with images and sounds of Earthly life recorded on it... just in case. (NASA)

Even though exoplanets are being found on a nearly daily basis, and it’s only a matter of time before a rocky, Earthlike world with liquid water on its surface is confirmed orbiting another star, that’s no guarantee of the presence of alien life — despite what conclusions the headlines will surely jump to.

There could be a billion habitable planets in our galaxy. But what’s the relationship between habitable and inhabited?” Joyce asks. “We don’t know.”

Still, we will continue to search for life beyond our planet, be it truly alien in nature… or something slightly more familiar. Why?

“I think humans are lonely,” Joyce said. “I think humans are like Geppetto — we want to have a ‘real boy’ out there that we can point to, we want to find a Pinocchio living on some extrasolar planet… and then somehow we won’t be such a lonely life form.”

And who knows… if any aliens out there really are a lot like us, they may naturally be searching for evidence of our existence as well. If only to not be so lonely.

Listen to the full PLoS podcast here.