Imagining aliens helps us think about evolution

If we ever do make contact with an extraterrestrial intelligence, what will it look like?  Hollywood has had no shortage of examples for films and television shows that feature aliens, but they are almost  always bipedal primates who speak English with a funny accent.  This  depiction is more the result of wardrobe budget constraints and the  flexibility of actors than it is the imagination of writers.  

Occasionally a film or show will depict an alien as a gelatinous blob  or an orb of light, which is a good start in the move away from  aliens-as-bipedal primates, but the alien-ignorance problem was handled best in the book and film version of Carl Sagan's Contact,in which the  extraterrestrial being whom his main character encounters (Ellie,  played by Jodie Foster) takes the form of her father (out of her memories)  because their presence is so wholly Other she would not have been  able to comprehend them otherwise.

Recently I had a little fun with this notion, producing a video of my 'Close Encounter Of The Third Kind' with an alien, who made  contact with me in — of all places — the offices of the The Skeptics Society.

Yeah, okay, a cheap Halloween mask is no substitute for the real  thing, but given the quality of the evidence presented by UFOlogists  and alien abductees — blurry photographs, grainy videos, and anecdotes  about things that go bump in the night — proof of close encounters of  the third kind remain masked in our collective psyches.   So, until contact is actually made, we are left with speculation on what aliens  would actually look like.

Check it out:

My explanation — that the chances of an ET turning out to be a bipedal primate are close to zero — is not one shared by all scientists. None  other than the Oxford evolutionary biologist Richard Dawkins wrote to Josh Timonen, the videographer who filmed and produced this piece:
I would agree with him in betting against aliens being bipedal primates and I think the point is worth making, but I think he greatly overestimates the odds against. Simon Conway Morris, whose authority is not to be dismissed, thinks it positively likely that aliens would be, in effect, bipedal primates. Ed Wilson gave at least some time to the speculation that, if it had not been for the end-Cretaceous catastrophe, dinosaurs might have produced something like the attached.
Dawkins then presented this page from Promethean Fire: Reflections on the Origin of Mindby Charles J. Lumsden and Edward O. Wilson, based on the paleontologist Dale Russell's evolutionary projection of how a bipedal dinosaur might have evolved  into something like us had the dinosaurs not gone extinct.

Lumsden Wilson Promethean Fire from Richard Dawkins

I then wrote back to Richard:

"It seems to me that if something like a bipedal primate (or the  equivalent thereof) has a certain inevitability to it because of how  evolution unfolds, then it would have happened more than once here.  In his book Nonzero, Robert Wright argues that our existence precludes other terrestrial intelligences of our level from arising, but Neanderthals were as close as one can get to a counterfactual experiment, and they had half a million years to themselves in Europe without our interference, and showed no signs of cultural progress whatsoever in that time (tool kits stayed the same, no symbolic art, etc.). So that seems to me a bit of data against that argument."

Richard then responded thusly:
But you are leaping from one extreme to the other. In the film  vignette, you implied a quite staggering rarity, so rare that you don't expect two android life forms in the entire universe. Now you are talking about 'a certain inevitability', and pointing out, correctly, that a certain inevitability would predict that androids  should have evolved more than once on Earth!

So yes, we can say that androids are fairly improbable, but not necessarily all that improbable! Anything approaching 'a certain inevitability' would mean millions or even billions of android life forms in the universe, simply because the number of available planets is so huge.   Now, my guess is intermediate between your two extremes.

I agree with you that androids are rare, that is indeed suggested by the fact that they have only evolved once on Earth. I agree with you that science fiction, and the alien abduction subculture, have an unseemly  eagerness to imagine androids, which you are right to denigrate. But  I suspect that androids are not so very rare as to justify the  statistical superlatives that you permitted yourself in the vignette.  

I have discussed such matters in the last chapter of The Ancestor's  Tale. I think Conway Morris goes too far in one direction, and you go  too far in the other.

A point well made, as Richard Dawkins’ points always are, and it’s a curious question as to how evolution might have played out on another planet, or in a re-run of the evolution of life on earth here.

This is the famous thought experiment proposed by the late Harvard paleontologist Stephen Jay Gould in his book Wonderful Life: The Burgess Shale and the Nature of History. If we replayed the tape of life on earth, and tweaked a few minor contingencies here and there back in the Cambrian explosion of life (as revealed in the Burgess Shale treasure trove of fossils), would we get anything like the life forms we have today, especially a bipedal primate like us? Gould famously answered no: “Replay the tape a million times from a Burgess beginning, and I doubt that anything like Homo sapiens would ever evolve again.”

Many scientists beg to differ. Simon Conway Morris, for example, in his book Life's Solution: Inevitable Humans in a Lonely Universe,argues that humans were an inevitable product of the necessitating laws of nature. (Paradoxically, he simultaneously claims that another intelligent species anywhere in the cosmos is so highly improbable that we are alone.) His central argument is based on the phenomenon of evolutionary convergence in which necessitating physical laws and biological constraints dictate a limited number of solutions to life’s problems: eggs, eyes, wings, brains, echolocation, sociality, and the like. 

Convergence is a well-known phenomenon in evolutionary theory, but in the last couple of decades biologists have focused more on biological uniqueness, noting that convergence is the exception, not the rule. The classification system of cladistics, in fact, is based on evolutionary novelties and uniqueness as the criteria of distinguishing species from one another. 

The paleontologist Donald Prothero, for example, notes that Conway Morris has missed Gould’s central point about contingency: “Once groups of organisms are established and develop a body plan and set of niches, biological constraints are such that convergence and parallelism can be expected. But the issue of who gets this head start in the first place may be more a matter of luck and contingency that has nothing to do with adaptation.” 

Consider the Burgess Shale chordate Pikaia, which led to the evolution of vertebrates and is thus our earliest ancestor. What if Pikaia had gone extinct like most of the rest of the Burgess fauna? Prothero notes that “there would have been no vertebrates, and half the examples of convergence that Conway Morris details could not have occurred, because they are peculiar to the basic vertebrate body plan, and not shared in any other phylum.” 

Would some other body plan have evolved intelligence? Not likely, Prothero counters. “The jointed-legged phylum Arthropoda is the most successful, diverse, and numerous organisms on the land, sea, and air today. This phylum includes the huge numbers and varieties of insects, spiders, scorpions, mites, ticks, millipedes, centipedes, and crustaceans. As numerous and diverse as they are, their habit of molting their exoskeletons when they grow means they can never exceed a certain body size—they would fall apart like a blob of jelly during their soft stage after molting without any skeletal support.” Molluscs are also supremely successful as clams, snails, and squids, “but their body plan yields few convergences with vertebrates, let alone humans.” 

Likewise, such phyla as the Echinodermata (sea stars, sea urchins, sea cucumbers, brittle stars, and sea lilies) are flourishing, says Prothero, “yet they are even less likely to produce a humanoid with their peculiar specializations, such as a radial symmetry with no head or tail, spiny calcite plates, and lack of eyes. In addition, they lack any sort of circulatory, respiratory, or excretory system, so they are forever bound to marine waters of normal salinity.” 

The chances of ET looking like a sea star, a millipede, or a spineless clam are far greater than ET looking like us. The fact that we’re our favorite species and thus depict aliens looking like us tells us more about our egos than evolution.