Here is that evidence.
Scientists at the National Institute of Aging have looked closely at the mathematics of DNA evolution and concluded that DNA (which is the basis of life and is in every cell in your body) is probably older than the Earth itself. Dr. Alexei Sharov estimates, from analysis of how long DNA takes to double its complexity (around 376 million years), that DNA itself is about 9.7 billion years old (older than Earth by 5 billion years, give or take)
Microbes have been found floating very high in the atmosphere; too high to have been churned up from the ground by hurricanes, storms or volcanoes, according to astronomers at Sheffield University in the UK. Presumably, lacking a terrestrial origin, the small bugs must come from outer space.
Plausible mechanisms by which microbes, viruses and the complex building blocks of life could have reached earth from outer space billions of years ago (or even now) have been discovered. For example, research shows that some hearty bugs can survive the vacuum and intense radiation of space, and may have hitched a ride on meteorites or comets.
All of the water on earth came from outer space, perhaps carrying primitive life forms with it. The existence of extremophiles (organisms that survive temperatures far in excess of boiling water, lack of oxygen or sun light) near ocean vents, and buried a mile below the surface, reinforces this possibility.
One interpretation of small squiggles found in a rock recovered in Antarctica that was ejected from Mars by an asteroid or meteor hit millions of years ago, is that the rock contains fossils of ancient single cell organisms. Although very controversial, this interpretation has not yet been conclusively disproven. If life forms are capable of catching a ride from Mars, perhaps they can come from other sources too.
Recently, astronomers studying a cloud of interstellar gas 25,000 light years from here detected the organic compound, cyanomethanimine a molecular building block of one of the components of DNA (Adenine). NASA scientists have also found Guanine and Adenine in micro meteorites that have probably not been “contaminated” by these building blocks of DNA from Earthly sources.
This raises an interesting question of what we mean by “origin of life.” If DNA evolved on earth from very complex molecules from space, did life originate here or elsewhere?
