If alien life developed according to the laws of evolution, it would have many similarities with earthly life. This is the conclusion reached by the authors of an article published in the International Journal of Astrobiology.
“A fundamental challenge for astrobiologists - scientists who study life in space - is to think about the possible options for the existence of extraterrestrial life,” says Samuel Lewin, a fellow in the Department of Zoology at Oxford University, the first author of the work. - It is difficult to make such predictions. We have only one example of life as a starting point - earthly. Previous approaches in astrobiology were mostly mechanistic: they made predictions based on what was known on Earth and relying on knowledge of chemistry, geology and physics. We propose an alternative approach that involves using the theory of evolution without reference to earthly data. This is a useful approach as it makes theoretical predictions applicable to silicon-based alien life, without DNA and breathing nitrogen."
Illustrations of adaptation organisms of varying complexity that we can imagine when thinking about aliens / University of Oxford
Based on the idea of natural selection, the team of scientists investigated the possible evolution of extraterrestrial life, as well as how complex organisms are formed. In the case of the Earth, the complexity was mainly increased due to the small number of events, as a result of which separate organisms were combined, which led to a leaping increase in complexity. One of such events was the formation of multicellular organisms from unicellular organisms. Both theory and data suggest that an extraordinary combination of conditions is needed for such an event.
Representative of a theoretical complex biological organism of extraterrestrial origin / University of Oxford
In the work, scientists make some predictions about the biological structure of complex extraterrestrial life forms. “We still can't tell if the aliens will walk on two legs and have big green eyes,” explains Lewin. “We predict that aliens, like humans, are hierarchical, with each individual constituent element cooperating to create a whole organism. At each level of the body structure, there are special mechanisms for maintaining cooperation, eliminating contradictions between subunits and maintaining integral functioning. We can even offer some options for such mechanisms."