When we think of space, apart from the infinite darkness that surrounds the universe, the thing that comes to our mind next is the life out of planet Earth. It goes without saying that in such a wide universe, there would be planets with ancient life forms.
However, research by astrobiologists from ANU Research School of Earth Sciences believes that maybe alien life got extinct early.
Indian-origin Aditya Chopra and Charley Lineweaver -- the researchers behind this paper call this the ¡°Gaian Bottleneck Hypothesis.¡± Aditya Chopra says in a statement, "The universe is probably filled with habitable planets, so many scientists think it should be teeming with aliens. Early life is fragile, so we believe it rarely evolves quickly enough to survive.¡±?
He further adds, "Most early planetary environments are unstable. To produce a habitable planet, life forms need to regulate greenhouse gases such as water and carbon dioxide to keep surface temperatures stable."
As per the paper, around four billion years ago, Earth, Venus and Mars would have been habitable for life forms. However, a billion years later, drastic changes in the environment turned the surfaces completely inhabitable -- Venus is hot as hell and Mars is just cold to the core.?
If any life would have existed on these planets, it would have survived in the sudden shift in climate that both the planets witnessed.?
Dr Chopra further states, ¡°The mystery of why we haven't yet found signs of aliens may have less to do with the likelihood of the origin of life or intelligence and have more to do with the rarity of the rapid emergence of biological regulation of feedback cycles on planetary surfaces."
Also, in case you remember humans or other creatures like the dinosaurs were multicellular species, which if I were to explain very plainly, means a cell spent years and years to evolve and turn into such a complex creature. The researchers feel that even if they were to find fossils of extinct life on these planets, it would be microbial and not multicellular, as they never got the time to truly evolve and turn into complex creatures.
While this theory isn¡¯t definite, it is an interesting hypothesis nonetheless.