“By now it has become a common futurist prediction and science fiction plot device that intelligent and sentient life forms can be created which are not biochemical in nature and are thus fundamentally different from all currently known life,” distinguished Princeton astrophysicist Edwin Turner wrote in an email to The Daily Galaxy. “Whether or not this would actually be possible,” he explains, “depends on the nature and origin of consciousness, a topic about which we have little more than entertaining whistling-in-the-dark guesses at this point and no clear path toward obtaining any better understanding of this deep mystery.”
Aliens Shaped by Natural Selection
In a landmark 2017 study published in the International Journal of Astrobiology scientists from the University of Oxford showed that aliens are potentially shaped by the same processes and mechanisms that shaped humans, such as natural selection and are like us, evolving to be fitter and stronger over time.
Only One Known Sample in the Universe
“A fundamental task for astrobiologists is thinking about what extraterrestrial life might be like.” said Sam Levin, a researcher in Oxford’s Department of Zoology. “But making predictions about aliens is hard,” he noted “We only have one example of life – life on Earth — to extrapolate from. Past approaches in the field of astrobiology have been largely mechanistic, taking what we see on Earth, and what we know about chemistry, geology, and physics to make predictions about aliens.”
By predicting that aliens have undergone major transitions – which is how complexity has arisen in species on Earth, we can say that there is a level of predictability to evolution that would cause them to look like us.
“In our paper,” said Levin, “we offer an alternative approach, which is to use evolutionary theory to make predictions that are independent of Earth’s details. This is a useful approach, because theoretical predictions will apply to aliens that are silicon based, do not have DNA, and breathe nitrogen, for example.”
Alien Natural Selection
Using this idea of alien natural selection as a framework, the team addressed extra-terrestrial evolution, and how complexity will arise in space.
Species complexity has increased on the Earth as a result of a handful of events, known as major transitions. These transitions occur when a group of separate organisms evolve into a higher-level organism – when cells become multi-cellular organisms, for example. Both theory and empirical data suggest that extreme conditions are required for major transitions to occur.
The paper also makes specific predictions about the biological make-up of complex aliens, and offers a degree of insight as to what they might look like.
“We still can’t say whether aliens will walk on two legs or have big green eyes<” said Levin. “But we believe evolutionary theory offers a unique additional tool for trying to understand what aliens will be like, and we have shown some examples of the kinds of strong predictions we can make with it.”
“By predicting that aliens have undergone major transitions – which is how complexity has arisen in species on Earth, we can say that there is a level of predictability to evolution that would cause them to look like us.”
‘Like humans, we predict that they are made-up of a hierarchy of entities, which all cooperate to produce an alien. At each level of the organism there will be mechanisms in place to eliminate conflict, maintain cooperation, and keep the organism functioning. We can even offer some examples of what these mechanisms will be.
‘There are potentially hundreds of thousands of habitable planets in our galaxy alone. We can’t say whether or not we’re alone on Earth, but we have taken a small step forward in answering, if we’re not alone, what our neighbors are like.’
Rare Evolutionary Transitions
In subsequent 2019 research from the University of Oxford have created a statistical model that shows the chances of intelligent life existing elsewhere in the Universe are slim. “It’s still unknown,” observes mathematical biologist Michael Bonsall, “how abundant extraterrestrial life is, or whether such life might be intelligent. On Earth, numerous evolutionary transitions were needed for complex intelligent life to emerge, and this occurring relatively late in Earth’s lifetime is thought to be evidence for a handful of rare evolutionary transitions.”
“In addition to the evolutionary transition,” writes Bonsall, “the emergence of intelligent life also requires a set of cosmological factors to be in place. These include whether the planet is in the right place for water to be present, whether life emerges from the water and whether the planet itself is habitable. Most crucial in this is the lifetime of the star the planet is orbiting; if this lifetime is short in comparison to the necessary evolutionary transitions for life, then intelligent observers might never get a chance to emerge (often referred to as the Great Filter).”
The Daily Galaxy, Avi Shporer, Research Scientist, MIT Kavli Institute for Astrophysics and Space Research via Oxford University and Edwin Turner. Avi was formerly a NASA Sagan Fellow at the Jet Propulsion Laboratory (JPL).
Your free twice-weekly fix of stories of space and science –a random journey from Planet Earth through the Cosmos– that has the capacity to provide clues to our existence and add a much needed cosmic perspective in our Anthropocene epoch.