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.

Continue reading “The Early Earth was Really Horrible for Life”

Life on Earth Needed Iron. Will it be the Same on Other Worlds?

The Juno spacecraft took this image of Earth during a gravity assist flyby of our planet in 2013. Credit: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill.

A lot has to go right for a planet to support life. Some of the circumstances that allow life to bloom on any given planet stem from the planet’s initial formation. Here on Earth, circumstances meant Earth’s crust contains about 5% iron by weight.

A new paper looks at how Earth’s iron diminished over time and how that shaped the development of complex life here on Earth. Is iron necessary for complex life to develop on other worlds?

Continue reading “Life on Earth Needed Iron. Will it be the Same on Other Worlds?”

Animals Could Have Been Around Hundreds of Millions of Years Earlier Than Previously Believed

Credit: Elizabeth Turner/Laurentian University

According to the most widely accepted theories, evolutionary biologists assert that life on Earth began roughly 4 billion years ago, beginning with single-celled bacteria and gradually giving way to more complex organisms. According to this same evolutionary timetable, the first complex organisms emerged during the Neoproterozoic era (ca. 800 million years ago), which took the form of fungi, algae, cyanobacteria, and sponges.

However, due to recent findings made in the Arctic Circle, it appears that sponges may have existed in Earth’s oceans hundreds of millions of years earlier than we thought! These findings were made by Prof. Elizabeth Turner of Laurentian University, who unearthed what could be the fossilized remains of sponges that are 890 million years old. If confirmed, these samples would predate the oldest fossilized sponges by around 350 million years.

Continue reading “Animals Could Have Been Around Hundreds of Millions of Years Earlier Than Previously Believed”

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. Credit: NASA
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. 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.

Continue reading “Science Fiction Might Be Right After All. There Might Be Breathable Atmospheres Across the Universe”

About 2.3 Billion Years Ago, a Firehose of Oxygen was Released Into the Atmosphere

Salts left over from ancient seawater reveal new information about the oxygenation of the Earth’s atmosphere more than 2 billion years ago. Shown here is a sample of 2-billion-year-old salt (pink-white recrystallized halite) with embedded fragments of calcium sulfate from a geological drill core in Russian Karelia. Credit: Aivo Lepland, Geological Survey of Norway; courtesy of Science/AAAS

Billions of years ago, Earth’s environment was very different from the one we know today. Basically, our planet’s primordial atmosphere was toxic to life as we know it, consisting of carbon dioxide, nitrogen and other gases. However, by the Paleoproterozoic Era (2.5–1.6 billion years ago), a dramatic change occurred where oxygen began to be introduced to the atmosphere – known as the Great Oxidation Event (GOE).

Until recently, scientists were not sure if this event – which was the result of photosynthetic bacteria altering the atmosphere – occurred rapidly or not. However, according to a recent study by a team of international scientists, this event was much more rapid than previously thought. Based on newly-discovered geological evidence, the team concluded that the introduction of oxygen to our atmosphere was “more like a fire hose” than a trickle.

Continue reading “About 2.3 Billion Years Ago, a Firehose of Oxygen was Released Into the Atmosphere”