life on Earth Archives

July 8, 2024July 8, 2024 by Mark Thompson

Ammonites Were Doing Fine Until the Asteroid Hit

Ammonites basking under the Late Cretaceous sun. Artwork by Callum Pursall (@cpursall on X)

I must confess, I think asteroids and I think of movies like Deep Impact or Armageddon! Scientists think that an asteroid like the ones that appeared in the Hollywood blockbusters struck Mexico 66 million years ago and led to the extinction of the dinosaurs. It now seems they may not have been the only ones that were wiped from our planet. Ammonites are marine mollusks that flourished for 350 million years but they were wiped out too. Some research suggests they were struggling in North America but thriving in other parts of the world.

June 14, 2024June 14, 2024 by Mark Thompson

Moon Lander Detects Technosignatures Coming from Earth

Touch down! A NOVA-C lander named Odysseus and built by the company Intuitive Machines lands on the surface of the moon. (Credit: Intuitive Machines)

The search for life has to be one of the most talked about questions in science. The question is, what do you look for? The Odysseus lunar lander has recently detected signs of a technologically advanced civilisation…on Earth! The lander is equipped with an instrument called ROLSES which has probed the radio emissions from Earth as if it was an exoplanet to se if it could detect signs of life!

May 18, 2024May 18, 2024 by Laurence Tognetti

Did Earth’s Multicellular Life Depend on Plate Tectonics?

Graphic depicting the last 1.6 billion years of Earth’s tectonic history. (Credit: Figure 2 from Stern & Gerya (2024))

How did complex life emerge and evolve on the Earth and what does this mean for finding life beyond Earth? This is what a recent study published in Nature hopes to address as a pair of researchers investigated how plate tectonics, oceans, and continents are responsible for the emergence and evolution of complex life across our planet and how this could address the Fermi Paradox while attempting to improve the Drake Equation regarding why we haven’t found life in the universe and the parameters for finding life, respectively. This study holds the potential to help researchers better understand the criterion for finding life beyond Earth, specifically pertaining to the geological processes exhibited on Earth.

February 13, 2024February 13, 2024 by Evan Gough

Cosmic Dust Could Spread Life from World to World Across the Galaxy

Could life spread throughout the galaxy on tiny grains of dust? It would be a perilous journey, but new research shows its possible and calculates how long it would take to spread. Image Credit: ESO

Does life appear independently on different planets in the galaxy? Or does it spread from world to world? Or does it do both?

New research shows how life could spread via a basic, simple pathway: cosmic dust.

January 11, 2022January 11, 2022 by Evan Gough

Nearby Supernovae Were Essential to Life on Earth

Distant past supernovae could be linked by cosmic ray particles to climate change on Earth and changes in biodiversity. Courtesy: Henrik Svensmark, DTU Space.

It’s almost impossible to comprehend a supernova explosion’s violent, destructive power. An exploding supernova can outshine its host galaxy for a few weeks or even months. That seems almost impossible when considering that a galaxy can contain hundreds of billions of stars. Any planet too close to a supernova would be completely sterilized by all the energy released, its atmosphere would be stripped away, and it may even be shredded into pieces.

But like many things in nature, it all comes down to dose.

A certain amount of supernova activity might be necessary for life to exist.

January 10, 2022January 10, 2022 by Evan Gough

The Early Earth was Really Horrible for Life

The Blue Marble image of Earth from Apollo 17. Credit: NASA

Earth has had a long and complex history since its formation roughly 4.5 billion years ago. Initially, it was a molten ball, but eventually, it cooled and became differentiated. The Moon formed from a collision between Earth and a protoplanet named Theia (probably), the oceans formed, and at some point in time, about 4 billion years ago, simple life appeared.

Those are the broad strokes, and scientists have worked hard to fill in a detailed timeline of Earth’s history. But there are a host of significant and poorly-understood periods in the timeline, lined up like targets for the scientific method. One of them concerns UV radiation and its effects on early life.

A new study probes the effects of UV radiation on Earth’s early life-forms and how it might have shaped our world.

October 3, 2021October 3, 2021 by Scott Alan Johnston

When Did Photosynthesis Begin?

Sometime around 2.4 billion years ago, a nascent planet Earth underwent one of the most dramatic changes in its history. Known as the Great Oxidation Event, this period saw Earth’s atmosphere suddenly bloom with (previously scarce) molecular oxygen. The rapid alteration of the atmosphere’s composition was nothing short of a cataclysm for some early lifeforms (at the time, mostly simple celled prokaryotes). Anaerobic species – those that dwell in oxygen-free environments – experienced a near extinction-level event. But the Great Oxidation was also an opportunity for other forms of life to thrive. Oxygen in the atmosphere tempered the planetary greenhouse effect, turning methane into the less potent carbon dioxide, and ushering in a series of ice ages known as the Huronian Glaciation. But oxygen is an energy-rich molecule, and it also bolstered diversity and activity on the planet, as a powerful new source of fuel for living organisms.

The cause of this dramatic event? The tiniest of creatures: little ocean-dwelling cyanobacteria (sometimes known as blue-green algae) that had developed a new super-power never before seen on planet Earth: photosynthesis. This unique ability – to gain energy from sunlight and release oxygen as a waste product – was a revolutionary step for so small a critter. It quite literally changed the world.

June 2, 2020June 2, 2020 by Evan Gough

The Meteor Impact that Wiped Out the Dinosaurs Created a Vast Underground Hydrothermal System

A Three-dimensional cross-section of the hydrothermal system in the Chicxulub impact crater and its seafloor vents. The system has the potential for harboring microbial life. Illustration by Victor O. Leshyk for the Lunar and Planetary Institute.

The Chicxulub impact event was an enormous catastrophe that left a huge imprint on the Earth’s surface. Not only did it cause the mass extinction of the dinosaurs, it left a crater 180 km (112 miles) in diameter, and deposited a worldwide layer of concentrated iridium in the Earth’s crust.

But a new study shows that the impact also left its mark deep underground, in the form of a vast hydrothermal system that modified a massive chunk of the Earth’s crust.

March 10, 2020March 10, 2020 by Evan Gough

Life Could be Common Across the Universe, Just Not in Our Region

The building blocks of life can, and did, spontaneously assemble under the right conditions. That’s called spontaneous generation, or abiogenesis. Of course, many of the details remain hidden to us, and we just don’t know exactly how it all happened. Or how frequently it could happen.

December 18, 2019December 18, 2019 by Evan Gough

Science Fiction Might Be Right After All. There Might Be Breathable Atmospheres Across the Universe

This view of Earth’s horizon was taken by an Expedition 7 crewmember onboard the International Space Station, using a wide-angle lens while the Station was over the Pacific Ocean. A new study suggests that Earth's water didn't all come from comets, but likely also came from water-rich planetesimals. Credit: NASA

The last few years has seen an explosion of exoplanet discoveries. Some of those worlds are in what we deem the “habitable zone,” at least in preliminary observations. But how many of them will have life-supporting, oxygen-rich atmospheres in the same vein as Earth’s?

A new study suggests that breathable atmospheres might not be as rare as we thought on planets as old as Earth.