No one is saying that Homo sapiens climbed out of their spaceships fully formed on planet Earth one day. We obviously spent a lot of time evolving on Earth.
However, scientists have difficulty tracing our most distant origins—that is, our basic building blocks. Even though it sounds straight out of a science fiction movie, it’s hypothesized that life, including human life, initially came from outer space. That’s right, aliens may be our ancestors.
Panspermia, the transfer of viable organisms between planets, is considered a serious hypothesis by planetary scientists. It seems utterly bizarre, but this idea is so highly regarded in the scientific community that it’s being funded by NASA, MIT, and Harvard, to name a few.
There are many subsets of belief within this general hypothesis, like the purposeful planting of intelligent life by aliens, which is called directed panspermia. However, the most widely accepted notion is called ballistic, or interplanetary, panspermia. It’s the idea of life being exchanged between planets within a solar system.
There are many reasons to believe we may not be Earthlings after all.
1 Fossil Evidence
Currently, the earliest sign of life on Earth is from 3.83 billion years ago. During this period, a series of formidable meteor showers occurred. This heavy barrage of comets colliding into Earth suggests that any life that was forming at that time would have certainly faced extinction.
Remember the dinosaurs? Meteors are no joke. That was just one meteor the size of Mount Everest, but it made the Earth’s surface hotter than the Sun after crashing “20 times faster than a bullet.” While it seems apparent that these fireballs of fury snuffed out any life on Earth, they may have also been vessels for the life to come.
Evolution is agonizingly slow. It took several billion years for single-cell life to become multicellular, for example. So, how is it that directly after the most epic meteor shower our planet has ever seen, Earth was ripe and ready to spontaneously spawn DNA-based life? The planet hardly had time to cool down enough to support life, let alone create it.
The period of meteor showers ended sometime earlier than approximately 3.8 billion years ago. Evidence of life shows up in the fossil records from 3.83 billion years ago. If Earth was cooling down then, life evolved in the blink of an eye from an evolutionary standpoint. Unless, of course, life had already arrived. Many scientists hold these ancient fossil records as evidence of panspermia.