‘Suppose you knew that complex aliens existed and that they were on their way to planet Earth. Would you really be most curious about their color? Or would you like to know, just to name a few, whether they are friendly or hostile? And, in the latter case: do they have legs to run towards you?”
Zoologist Arik Kershenbaum (59) walks briskly through the long corridors of the nineteenth-century Girton College, just outside the center of Cambridge in the United Kingdom. He just did, during a lunch in the stately dining hallexplained the question he has been asked ad nauseam in recent years: whether Martians are green. “But even if we could find out what color they are, such a fact in itself would not be that interesting.
It is not the what questions that count in zoology, but the why questions. Why would aliens be colored at all? Why is it likely that they move, and why in any complex society can you assume that there are hunters and prey?” Then, upon opening his office: “Sorry for the mess. It is a busy month – first on tiger field work to southern Nepal and later at New Year’s I will be in Yellowstone to study wolf communication.”
At first glance, Kershenbaum’s office looks like a typical zoologist’s room. Stuffed osprey on the cupboard, diagrams about evolution on the whiteboard, books about animal language on the cupboard. There is a large stuffed dog on the couch; a memory of his recently deceased canaan dog Darwin. “Students regularly came here to pour out their hearts to him.”
But if you look around a little longer, you will notice visual hints that match his extra expertise: exobiology. Science fiction books, an article using the term ‘xenolinguistics’ and of course his own bestseller The Zoologist’s Guide to the Galaxy. In it, he outlines, with examples from evolutionary biology and linguistics, which rules complex extraterrestrial life will comply with.
1Natural selection also occurs on other planets
“I have no doubt that extraterrestrial life will be discovered in the foreseeable future. The chance that this concerns intelligent, complex life is much smaller. But suppose we meet such an alien civilization, they will have a few things in common with us, including evolution through natural selection. In short: the fact that over time there is an accumulation of good qualities and a rejection of the bad ones. Natural selection is not tied to DNA or other earthly building blocks, you can define it in strict mathematical terms, without referring to, for example, a specific method of reproduction. It’s the only logical way to evolve. Like terrestrial life, extraterrestrial life will start out as something simple and diversify step by step.”
2The function is decisive for the form
“On our planet you often see convergent evolution: the development of similar adaptations in species that are not at all related to each other but do occupy similar niches. Take the Tasmanian tiger, for example, an extinct marsupial that looked exactly like a wolf. Or think of birds and bats: they both fly, but belong to completely different groups. In paleontology you also see that there are similarities between extinct and current species. We can conclude quite a lot about dinosaur behavior by comparing it with living species. For example, we conclude that there were predatory dinosaurs based on their pointed teeth.
“That doesn’t mean the universe is bursting with alien wolves and bat aliens. But beings from other planets will also fill all kinds of roles in all kinds of niches, and to some extent their form will be dictated by their function. For example, if you are a fast predatory alien, a bulky body is of no use to you.”
3Alien life moves (with legs or fins)
“Scientists assume that the earliest life on Earth was static. But even those oldest colony-forming bacteria, stromatolites, moved in a sense: once sand and dead organic matter blocked the incoming radiation from their energy source—the sun—they grew upward, in new mats on top of the old. And plants and mushrooms also experience some degree of movement.
“Yet locomotion by animals is of a completely different order. With fins or legs you can get from place A to place B much faster and easier. That’s good, because a cruel, simple law of evolution is that energy is limited. And so you have to be creative to get enough of it. For example, by reaching food sources faster than other species.
Movement is a driver of complexity
“Movement is a driver of complexity. Moving animals sometimes have to make decisive decisions quickly, and that time-dependent race for speed has been a driving force in the development of communication and intelligence.
“If smart, communicating aliens exist, then my suspicion is that they also move. And if they do that on land, they will have to have some kind of legs. Presumably there is bilateral symmetry, just like with us: it is easier to move forward on two or four legs than on three. But perhaps they rather have many small tubular suction-cup-like legs, like the starfish.”
4Aliens have a way of communicating
“In the animal world we see that there are all kinds of verbal and non-verbal communication, which are closely related to the conditions in which species live. The same would apply to extraterrestrial life. Visual communication, for example, with gestures but also colors and patterns, is of course only useful if aliens can also perceive the signals, i.e. if there is light and good visibility. Sounds – for example to attract mates, scare away enemies or track prey – can be very useful in the darkness, as you see in echolocation. But they can also be useful over long distances, especially in densely vegetated areas.
“Electronic signals, on the other hand, work at short distances and especially underwater. They are not necessary in clear water – where visual signals work just as well – but in dark oceans, such as those found on Saturn’s moons, for example, they could be ideal. In short, a lot is related to the planet on which alien life would live.
“Then there is the issue of language. This is often seen as a uniquely human concept, but the definition is quite vague. As far as I’m concerned, you can say that language is a way to communicate complex concepts, and that it is subject to natural selection just like ourselves. And in that sense, it is likely that complex extraterrestrial life at least has some form of language – whether we can understand it or not.”
5There will be hunters and prey
“One of the most important questions I try to answer in my book is whether aliens are social. If they work together like us, they will also be able to develop advanced technologies, and if they have groups of friends like us, then there is a greater chance that we will get along with them too. But to predict whether aliens are group animals, you first need to understand why animals live in groups or not.
“Living together has several advantages: you can share food with each other and you are often safer around predators. Predation is universal, which inevitably follows from natural selection. No ecosystem can exist for long periods of time without someone trying to take a bite from someone else. The competition for energy is simply too great for that.
If aggression prevails for too long, a civilization will eventually collapse
“Extraterrestrial civilizations will therefore also include predatory aliens. Predation is a powerful driver of evolution, because hunters and prey become entangled in an evolutionary arms race, and there is a good chance that group formation will also occur among aliens, partly as a protection mechanism against those predators. It is hoped that any alien society we may one day encounter has at least passed the most aggressive stage. If it is an advanced society, I assume so, because if aggression prevails for too long, a civilization will eventually collapse. As we humans are currently well on our way to doing with ourselves.”
We must not only look outward, Kershenbaum wants to say, but also inward. “The word ‘alien’ means ‘from another place’, but is often also used in the context of ‘crazy’ or ‘different’. And as soon as you let that meaning predominate, it promotes polarization. While: if you delve into others – whether they concern fellow humans or other animal species, or aliens – then you understand much better why they have developed certain qualities and it is easier to feel a connection.”