You might be inclined to think that something as complex as life should be rare, and that it probably took a very long time to come into existence.
But two new pieces of evidence suggest that life beyond Earth might be more likely than we think, and that it began on Earth almost instantaneously — at least on a geological time scale.
Last month, scientists uncovered evidence that life appeared on Earth 300 million years earlier than we previously thought. They found fossils in Western Australia that date back 4.1 billion years.
That means that after the Earth formed, it took only 400 million years for life to get cranking. Four hundred million years is really just the blink of an eye compared to the planet's 4.5-billion-year existence.
"Life on Earth may have started almost instantaneously," one of the lead researchers, Mark Harrison, said in a press release. "With the right ingredients, life seems to form very quickly."
And speaking of the right ingredients, scientists just uncovered evidence that our planet has had water on it since the very beginning. Water is essential to life — everywhere that we find water on Earth, we find life.
It's so critical that many astronomers use a "follow the water" mantra to guide them in their search for life beyond Earth. That's why scientists are pushing for more missions to Europa and Enceladus — two moons that we know have water, and therefore may support life.
But the origin of Earth's water has always been a mystery to scientists. The popular theory is that it was carried here by asteroids that pummeled Earth and left the moon heavily cratered about 3.9 billion years ago, according to NASA. But this new discovery seems to rule out that theory as the initial source of Earth's water.
The research was published on November 13 in the journal Science.
A team of researchers examined lava that bubbled up from deep within the Earth's mantle on Baffin Island in Canada and the Holuhraun lava field in Iceland to look for signs of water.
When an eruption happens, lava flow can carry chunks of rock up from deep within the Earth. The lava flow quickly hardens, and scientists are able to study its composition.
Lava flow on Baffin Island pulled up rock from deep within the Earth that dates back to 4.5 billion years ago. Its chemical composition is preserved deep underground, so it's a pristine record of the material that first formed Earth.
In this case, the researchers were looking for rock with hydrogen and deuterium — a heavier type of hydrogen. Their presence is a chemical signature of water, and the ratio of the two can help researchers trace the origin of the water. In the rock that the researchers tested, the ratio was close to what we see in water-carrying chunks of asteroid.
That means that the Earth may have formed the same way asteroids did. Scientists already know there was water present in the cloud of dust that spawned our solar system. Scientists think that water-soaked dust coalesced and hardened to form asteroids and later planets. So some water has possibly been on Earth since it first formed.
Put together, these findings have profound implications for the likelihood of life beyond Earth.
It suggests it might be easier for life to arise than previously thought. And some of the other planets in our solar system and beyond the Milky Way probably also formed out of water-soaked dust. That means they all had one of the most important ingredients for life from the very beginning.
Some scientists are skeptical of this new water research, but if it's true, "that would make habitable worlds much more likely," Horst Marschall, a geoscientist at Woods Hole Oceanographic Institution, told New Scientist.
