Aliens often look like us in movies — will they look like us in real life?

If you're a fan of science-fiction programs and movies, you might have recognized a pattern. 

Aliens, lots of times, look like us. They might have interesting forehead wrinkles, or pointy ears, but the basic humanoid pattern is more common than not.

And when they don't look like us, they look like things that are familiar — if perhaps disturbing — like insects, or reptiles or even squid.

This could just be due to the limited imagination, and maybe budgets, of Hollywood creators.

But it could also be something we might expect to see if or when we encounter alien life. 

The argument is simple: The evolutionary forces and rules that made us the way we are must also apply to life on other planets. Laws of nature are common across the universe.

That's the premise of zoologist Arik Kershenbaum's book, called The Zoologist's Guide to The Galaxy: What Animals on Earth Reveal About Aliens and Ourselves.

Kershenbaum is a lecturer and fellow at Girton College at the University of Cambridge in England. He spoke with Quirks & Quarks host Bob McDonald.

Zoology and the study of extraterrestrial life may seem like two different subjects at first glance. What inspired you to write a book that combines the study of both? 

Well, the study of zoology, or the way that we zoologists pursue our science, is always about asking "why" questions. Asking why animals are the way they are, why they look the way they do, why they behave the way they do. And the answer to all of these "why" questions always come down to evolution, to the different ways that evolutionary forces are acting on these animals.

So it's really not that big a stretch to see that the evolutionary forces that we understand from studying animals all this time on Earth, those same forces are universal. Those are the kinds of things that will make animals on Earth eat each other. They'll make creatures on other planets eat each other because the fundamental laws are still the same.

Carl Sagan believed in life and other planets and that they indeed would have similar characteristics to life here on Earth. But we're now learning that planets, even those within our own solar system, are really, really different from Earth. So how can it be both ways? How can alien life be similar to ours on such different worlds? 

The interesting thing here is that the evolution and the process of evolution and the rules by which evolution works are pretty much independent of the underlying biology. They're pretty much independent of the biochemistry. They're independent of exactly what kind of metabolism or what kind of chemicals are being used.

You don't need DNA for evolution. OK, there's lots of different ways that evolution could work with different kinds of chemicals, different kinds of chemistries. You could have animals based on DNA like ours. You could have creatures that are based on a different chemical that transmits information from one generation to the next. You could have animals that don't rely on water, perhaps even some other solvent they could use. But still, the evolutionary processes are still going to be the same, survival of the fittest. 

How will what we know about the general principles of life here help us know what to expect when, hypothetically, we meet intelligent aliens? 

Well, when we meet intelligent aliens — if we were to meet intelligent aliens, of course — then that's slightly different situation, because any alien species or any alien civilization that possesses the technological ability to come and visit us is technologically advanced with access to power resources that are just quite beyond our imagination. So I think that's actually quite unlikely.

We may be able to communicate with intelligent alien civilizations if they exist using radio communication, for instance. If we were to make contact with an alien civilization, then my big hope is that they have their own equivalent of David Attenborough and that they can send us lots of TV documentaries of what the alien life is like on their planet. And then we would be able to compare. 

Science fiction has fun with aliens. Have you seen any clues there that lead you to think, "there's  a good idea?" 

The role of science fiction is to allow us to suspend disbelief a little bit so that we can examine difficult aspects of human nature. You know, you have a Vulcan who doesn't have any emotion, and that allows us to explore what that means. The Klingons, who are warlike and honour driven, make it an easy way to explore the difficulties of being human. So in that sense, really, most science fiction is not about what alien life is going to be like.

But having said that, you could also say that if I'm right, and if a lot of what the fundamental laws of what alien life is going to be like are similar to the laws on on Earth, and in particular, if intelligent technological alien life must have gone through a similar sort of evolutionary history to ourselves — certainly a similar social history to ourselves — then maybe we can expect alien intelligent life forms to be rather like ourselves.

And then maybe it's not so unreasonable to think about them as slightly different humans with different characteristics, much different priorities, different outlooks. And in that sense, actually, I do think that these science fiction portrayals of humanoid aliens are actually quite stimulating. 

You ask "Can we continue to trust our intelligence to get us out of any impending ecological disasters?" So do we need help from artificial life forms out there as well? 

Well, one of the most famous solutions to the big question — "Why haven't we discovered any aliens? If they are alien civilizations in the universe, why haven't they contacted us?" — one of the most famous solutions to that paradox is that it's quite likely that civilization, once it reaches a certain technological advancement, simply destroys itself.

And from our experience, that would seem to be a very reasonable hypothesis. I mean, we are not doing a good job. Prospects for the human race do not look good. Whether we will still be here in a thousand years is a question that we don't know the answer to. So it could just be that once you reach a certain level of technological mastery over your environment, but haven't reached a level of sophistication and wisdom to be able to protect your environment, then you're essentially doomed to extinction. 

Produced by Mark Crawley. Q&A has been edited and condensed for clarity.