The universe is a big place. Thinking about how we fit in is part of what makes humans (and cats like me) special.
I talked about your question with my friend Afshin Khan who studied astrobiology and environmental sciences at Washington State University. Astrobiologists are exploring how life began. They are also looking for signs of extraterrestrial life.
Khan told me your question is a big mystery.
“We have very good ideas about what could happen,” she said. “In different laboratories around the world, we have come very close to simulating some of these conditions. But the simulations can come very close to what was happening on early Earth.”
We have a good feeling when life began. We know that the Earth formed about 4.5 billion years ago. The oldest fossils on Earth are stratolites, which are layers of rock and microbes. They are at least 3.5 billion years old. Therefore, there must have been living microbes on Earth at that time.
Living things need energy and water. They also need organic molecules. These molecules make up your cells. They drive the chemistry that happens inside your body. This chemistry is how your cells get oxygen. It’s how you turn food into energy and move your muscles.
But how can these complex organic molecules evolve from simple molecules and chemistry?
To find out, scientists made a glass device to mimic extremely hot conditions on early Earth. There were a lot of gases, water and lightning. Therefore, they put gases and water in the vitreous apparatus. They slapped her with electricity. After a week, the water turned brown. It was full of organic molecules and the things that make up them.
Scientists conducted this experiment under many conditions. Khan even did it at Washington State University. One possibility is that a brown “soup” of organic molecules could clump together just as bacteria do today.
They could start doing alchemy together. Or they may have built a protective layer around themselves like a cell membrane.
Khan also told me that hydrothermal vents may hold clues to how life began. These are hot springs on the bottom of oceans or lakes. The water in these openings can reach 750 degrees. There is no sunlight there, but there is a lot of stress and toxic metals. It is not a place where you would expect to find life.
But the scientists who discovered these vents in 1977 found life there. Beings that love extreme places are called extremists. Some extreme microbes live in the vents. They use toxic chemicals to produce energy – just like plants use the sun to generate energy.
Khan told me that the early Earth had hydrothermal vents, perhaps ideal places for life to begin. They have water and energy. They have a lot of chemicals and chemistry going on. Scientists have shown that very simple organic molecules and cells can form there.
Another idea is that life did not begin on Earth at all.
“For all we know, we can find out that we are in fact a Martian!” Khan said. “Maybe we evolved from life that came from Mars.”
At the time when the Earth was formed, there were a lot of collisions in space. It is possible that a meteorite from Mars was thrown to Earth. The first cells or organic molecules may have stopped. Earth was perhaps the perfect hot, watery, lightning-filled place for the “seed” of life to grow.
“We’re made of the same elements that stars are made of,” Khan said. “We have become smart enough that we seek to understand where we come from.”
We probably won’t know for sure how life on Earth began. But thinking about it makes us good astrobiologists and even better stewards of our planet and universe!
Do you have a scientific question? Dr. Wendy Sue Universe, WSU-based science writer and writer, via email at Dr.Universe@wsu.edu.