While scientists endlessly gaze into the universe looking for evidence of alien life, many wonder why it hasn’t been found yet. A new report suggests the reason may be because most early extraterrestrial lifeforms struggling to develop would have been wiped out due to a rapidly changing climate.
Dr. Aditya Chopra from the Australian National University Research School of Earth Sciences and Charley Lineweaver from ANU Planetary Science Institute have developed a hypothesis that alien life may have emerged on a faraway planet and then perished before astronomers were able to find them. The researchers say that the early lifeforms may not have evolved fast enough to deal with quickly changing climates on their home world.
“The universe is probably filled with habitable planets, so many scientists think it should be teeming with aliens,” Chopra said in a press release. “Early life is fragile, so we believe it rarely evolves quickly enough to survive.”
Besides climate change, the researchers also argue that life on an alien world may have emerged several times but was killed off by heavy bombardment of asteroids.
Factors such as a planet’s mass, atmospheric composition, and the amount of solar energy absorbed by a planet play a key role in a species’ survival, but other dynamics, like water supply and stable surface temperatures, are also equally essential. The Kepler mission has been looking for evidence of alien life and has located at least 1,039 planets with the right conditions so far.
“Feedback between life and environment may play the dominant role in maintaining the habitability of the few rocky planets in which life has been able to evolve,” they write in their paper, which is published in the journal Astrobiology.
Earth, Venus, and Mars may have all been able to sustain life four billion years ago. Yet, the climates of Venus and Mars went through periods of extreme heat and cold, so any form of early alien life may not have survived long enough to adapt.
Earth, being in a unique position around a stable star, was able to give birth to life and maintain an unwavering environment long enough for it to take hold. Even life itself helped maintain the atmosphere by carefully regulating greenhouse gases over four billion years.
“Life on Earth probably played a leading role in stabilizing the planet’s climate,” said Lineweaver.
As previously reported by the Inquisitr, NASA has been looking for evidence of alien life right in our own backyard. The space agency is looking at Jupiter’s icy moon Europa for a chance that microbial life has grown and spread throughout the vast ocean underneath the surface crust.
Often referred to as the Fermi Paradox, scientists question why all the potentially habitable planets in our galaxy, ones with water and chemicals needed to produce extraterrestrials, do not have any evidence of alien life. Chopra and Lineweaver think the answer to the paradox is their research, dubbed the “Gaian Bottleneck.”
“Our search for life beyond Earth may be thwarted by the short timescales over which planets may remain inhabited,” the authors write. “If it takes several billion years to develop radio telescopes, then the Gaian Bottleneck ensures that the vast majority of life in the universe is either young and microbial, or extinct.”
The scientists noted that the Gaian Bottleneck theory says most fossils of extraterrestrial life in the universe will be extinct microbial organisms, not more complex creatures like dinosaurs or humanoids, which take billions of years to develop.
There are an incalculable number of stars in the universe and the number of planets able to sustain life equally uncountable. Scientists believe the probability of another species either extinct or otherwise is out there, and it is only a matter of time before evidence of alien life is found.
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