Hollywood movies and science fiction literature feed the belief that extraterrestrials are otherworldly, monster-like beings who are very different from humans. But new research goes against our preconceptions or fantasies and suggests that we may have more in common with our extraterrestrial neighbours than we thought.
Ihere are at least 100 billion planets in our galaxy alone, and at least 20 % of them are probably in the habitable zone, that region of space capable of producing a biosphere. Even if this were to happen in only 0.001% of these planets it would still mean that there are 200,000 potentially life-bearing planets in our galaxy. All it would take would be one extraterrestrial life form to radically change our view of the Universe. So it's not surprising that there are hundreds of millions of dollars have recently been brought into astrobiology research, that the United States and Europe have recently invested in astrobiology initiatives and that many further work were made to try and predict what the aliens would look like. The problem, however, is that when we try to predict the nature of aliens, we have only one sample - the Earth - to extrapolate from. It's, therefore, extremely difficult to make those predictions.
Imagine an alien. These illustrations represent different levels of adaptive complexity that we might imagine when we think of aliens. (a) A simple molecule of replication, with no apparent design. This may or may not be subject to natural selection. (b) An incredibly simple entity, resembling a cell. Even something so simple has enough parts to be subject to natural selection. (c) An alien with many complex parts working together is likely to have experienced great transitions. Credit: Oxford University
In a new study published in the International Journal of Astrobiologyscientists from Oxford University are showing, for the first time, how the theory of evolution can be used to support predictions about extraterrestrials and better understand their behaviour. They argue that extraterrestrials are potentially shaped by the same processes and mechanisms that have shaped humans, primarily natural selection.
The theory supports the argument that alien life forms undergo natural selection and, like us, evolve to become stronger and more efficient over time.
Sam Levin, a researcher at the Department of Zoology at Oxford, has thus said : " A fundamental task for astrobiologists (those who study life in the cosmos) is to think about what extraterrestrial life could be. But making predictions about extraterrestrials is difficult. We can only extrapolate from one example of life - life on Earth. "
In the past, when scientists thought about what extraterrestrials might be, they used to implement an approach mechanics, based on what we know about the Earth, including chemistry, geology and physics.
For example, certain features have evolved several times on Earth, so we posit that extraterrestrial life forms will converge towards the same terrestrial mechanisms. Because eye organs have evolved at least 40 times and are relatively ubiquitous, we predict that they will evolve in the same way on other planets. Similarly, we have used a mechanistic understanding of chemistry and physics to make predictions about what is most likely to be found on other planets. For example, carbon is abundant in the Universe, chemically versatile and present in the interstellar medium, so exotic life forms are likely to be carbon-based. These types of predictions come from a mixture of mechanistic understanding and extrapolation of what has happened on Earth. But, in reality, there is no theoretical reason why aliens couldn't be silicon-based and... eyeless organisms.
" In our paper, we propose an alternative approach, which is to use evolutionary theory to make independent predictions of the characteristics we know about on Earth. This is a useful approach, because the theoretical predictions will apply to extraterrestrials that could be, for example, silicon-based instead of DNA-based, or that breathe nitrogen instead of oxygen. "
Using this idea of extraterrestrial natural selection as a framework, the team looked at extraterrestrial evolution and how complexity might manifest in space.
"The Octomite." A complex alien that comprises a hierarchy of entities, where each group of lower-level entities has aligned evolving interests, so that conflicts are effectively eliminated. These entities engage in division of labour, with different parties specializing in different tasks, so that they are interdependent. Credit: University of Oxford
Species complexity has increased on Earth due to a handful of events, known as major transitions. These transitions occur when a group of distinct organisms transforms into a higher level organism - when cells become multicellular organisms, for example. Both theory and empirical evidence suggest that extreme conditions are required for major transitions to occur.
The article also makes accurate predictions about the biological composition of complex aliens, and offers some understanding of what they might look like.
Sam Levin goes on: " We still can't tell if the aliens will walk on two legs or have big green eyes. But we believe that evolutionary theory offers a unique additional tool for trying to understand what extraterrestrials might be, and we've shown some examples of the kinds of strong predictions we can make with it. ".
By predicting that extraterrestrials have undergone major transitions - and this is how complexity has emerged in species on Earth - Oxford scientists claim that there is a level of predictability to evolution that would make them resemble what we Earth humans are.
" Like humans, we predict that they are made up of a hierarchy of entities, all of which cooperate to produce a living organism. At each level of this organism, there will be mechanisms in place to eliminate conflict, maintain cooperation and keep the organism functioning.. »
There are potentially hundreds of thousands of habitable planets in our galaxy alone. Last week, astronomers have again discovered about 20 exoplanets, relatively close and potentially habitable. We can less and less claim to be the only life form in the universe. But, with this Oxford study, we have taken a small step forward by proposing that, if we are not alone, our galactic neighbours could look very much like us...
Source: Oxford University
