An alternative universe, known as science fiction, has given our culture a whole zoo of alien species. From teddy bears like Ewoks to horrible creatures like “Aliens”, our collective imagination positively supports us with Hollywood images at the thought of extraterrestrial life. Whom to believe? What kind of aliens will appear when they appear on our radars – something completely different or strange versions of horror films from second-rate films?
One thing is for certain: aliens from other worlds will be subject to the same evolutionary forces as we are on Earth – natural selection. This conclusion was made by scientists from Oxford University, submitting his article to the publication in the International Journal of Astrobiology.
Scientists suggest that the evolutionary theory presented by Charles Darwin in his famous book “On the Origin of Species” 158 years ago can be used for predictions on the topic of extraterrestrial species. In particular, as scientists write, aliens will go through natural selection, because this is the only process by which organisms can adapt to the environment.
“Adaptation is what determines life,” says lead author Samuel Levin.
Although it is likely that NASA or some private enterprise, similar to SpaceX, will eventually stumble upon cosmic stones and open up microbial life in the not so distant future, aliens that Levin and his colleagues try to describe are much more complicated. Because natural selection works.
Let’s get a little refreshed in memory: natural selection is a process in which certain features in a particular population become more preferable. For example, take a group of brown and green beetles. Since birds prefer to eat green beetles, more brown beetles survive and reproduce. If this population pressure continues, brown beetles will become a dominant species. The browns will win, the green will lose.
And just as people are the result of millions of years of adaptation – for example, their eyes and thumbs – the aliens will consist of parts that were once free living, but eventually came together to work as one organism.
“Life has too many ingenious parts, too many complexities, so that this happens (by accident),” explains Levin. “Too complicated and too many things should work together and purposefully, so that it happens by chance. We need a process of creation, and this process is a natural selection. ”
Just do not think that aliens will be bipedal humanoids with large heads and almond-shaped eyes, says Levin.
“They can be created from completely different chemical things and visually unrecognizable,” he explains. “They will go through the same evolutionary history as we do. As for me, this is much more interesting and delightful than the fact that they will have two legs. ”
Lack of data
Seth Shostak, a leading astronomer at the SETI Institute and a host of the Big Picture Science radio program, believes that while the argument itself is interesting, he does not answer the question of the appearance of aliens.
Shostak argues that a more productive approach will be convergent evolution, when similar adaptations take place in similar environments, at least if one assumes terrestrial conditions like liquid oceans and thick atmospheres. For example, extraterrestrial species that develop in a liquid environment are more likely to have an elongated body that helps them move through water.
“The randomness and specificity of the environment will lead to changes on a foreign planet in the same way as we do, and there is no way to predict them,” concludes Shostak. “Alas, the exact space bestiary can not be described only by the inclusion of biological mechanisms. We need data. It is not enough to think about extraterrestrial life alone. We need to open it. ”
Search is on
The search is on. On the one hand, the task seems simple enough: in the Milky Way galaxy there are about 100 billion planets, and about 20% of them can produce the biosphere. Even if the evolution of life is an extremely rare process, then even conservatively estimated at 0.001% (200,000 planets), the chances will be quite high.
Of course, it is not so easy to place them on a segment of a billion light years.
Hunters of the planets can not even agree on what signatures of life to look for. There is an opinion that there is no smoke without fire. If the alien world is home to biological life, astrobiologists will look for the presence of “biosignature gases” produced only by extraterrestrial life.
Scientists are looking for such gases, studying the atmosphere of the planet against the background of starlight. Gases in the atmosphere absorb certain frequencies of stellar light, suggesting what happens in the cauldron of a particular planet.
The presence of oxygen, apparently, should be a biological beacon, but there are cases when the planet can produce false positive results: that is, for the appearance of oxygen on the planet, non-biological processes will respond. Scientists like Sarah Seeger, an astrophysicist at the Massachusetts Institute of Technology, argue that there are many examples of other types of gases produced by organisms even on Earth that could point to the life of another planet.
Life as it is
The existence of earthbound extremophiles – organisms that can exist under the most incredible conditions, such as in a cosmic vacuum – provides one more clue as to what kind of extraterrestrials we could eventually encounter.
Lynn Rothschild, an astrobiologist and synthetic biologist at the Ames Research Center in the Silicon Valley, takes extremophiles as the basis and brings to perfection using synthetic biology.
For example, say, bacteria can survive at a temperature of 120 degrees Celsius. The Rothschild laboratory can bring this threshold to 150 degrees. The idea is to bring life to such opportunities that it does not even need rockets.
Although scientists can not agree on where, how and what we will find in the search for extraterrestrial life, most of them are sure of the following: extraterrestrial life must exist.
“I would be surprised if there were no extraterrestrials,” Levin says. “Few things could shock me more than the conclusion that aliens do not exist. If I could make a bet, I would put everything in the fact that extraterrestrial life is somewhere there, and there are a lot of it. “
