Posted on: October 23, 2007 6:54 PM, by Brian Switek
Regardless of whether it was gradual or happened in a geologic instant, non-avian dinosaurs went extinct by approximately 65 million years ago, but the question of what they might be like today had they survived makes for some entertaining fiction. Most of such imaginary works are set on isolated islands or plateaus, “Lost Worlds” that have provided a refuge for dinosaurs (the most spectacular and enjoyable example being Weta Workshop’s companion book to Peter Jackson’s remake of King Kong entitled The World of Kong). Still, many of the dinosaurian hideaways do not take evolution into account, theropods, sauropods, hadrosaurs, and horned dinosaurs looking little different from what their Mesozoic forebears were supposed to have looked like during their heyday (Weta’s work is a pleasant exception to this rule). There are some authors, artists, and even scientists who have pondered what evolution would have done to dinosaurs had their extinction been avoided, however, the most (in)famous example being Dale Russell‘s “Dinosauroid.”
Unfortunately, I do not have the original 1982 Russell & Séguin paper that first proposed the “Dinosauroids” (pictured above) as a thought experiment, although today the figure is more prominent in online UFO conspiracy forums than in scientific discourse. Our awfully alien-like friend (a point I’ll return to later) still crops up every now and then though, and it was a more recent television appearance that inspired me to go back and look at the bug-eyed creature that I was first introduced to during the late 1980’s/early 1990’s;
From the BBC’s Horizon program, “My Pet Dinosaur.”
This clip brings up an important question, one that has important meaning for our understanding of evolution in general for our own history; are intelligent humanoids destined to evolve? Such a hypothesis invokes a philosophical idea of teleology, and while such a view that evolution direction (or at least inevitable outcomes) is entertained by some scientists, this type of argument is most commonly espoused by advocates of intelligent design. Indeed, those familiar with the views Simon Conway Morris will likely recall his long-standing public feud with Stephen Jay Gould over the Cambrian fossils of the Burgess Shale and the role of contingency in evolution relating to this issue, a topic that will loom large in this somewhat cursory analysis of the Dinosauroid and it’s philosophical underpinnings.
Before going into why Russell’s evolved Troodon looks so eerily familiar on multiple levels, I should reiterate what Russell has said in the past; the Dinosauroid was primarily a thought experiment in speculative biology. As he said himself in an interview given sometime in the year 2000;
The “dinosauroid” was a thought experiment, based on an observable, general trend toward larger relative brain size in terrestrial vertebrates through geologic time, and the energetic efficiency of an upright posture in slow-moving, bipedal animals. It seems to me that such speculation remains acceptable, particularly if directed toward non-anthropoid anatomical configurations. However, I very nearly decided not to publish the exercise because of the damaging effects it might have had on the credibility of my work in general. Most people remained polite, although there were hostile reactions from those with “ultra-quantitative” and “ultra-intuitive” world views.
Even though Russell stated that the Dinosauroid model is still acceptable, Russell obviously had some reservations about publishing the paper or giving too much attention to his interpretation of a Troodon 65 million years after the end of the Cretaceous. As Michael Ryan noted on his own entry on this topic on Paleoblog, a painting of a family of dinosauroids was planned for Russell’s book An Odyssey in Time: The Dinosaurs of North America, and although the maquettes of the scene still exist in museum storage, the illustration was pulled from the book, a decision that I think was wise (despite how interesting such a scene would be). Still, the famous image of a humanoid dinosaur standing next to it’s Troodon ancestor is a provocative one, a hypothetical relationship that confronts us with some important questions about our own evolution.
At the time that Russel and Séguin formulated their hypothesis, Troodon was known as Stenonychosaurus inequalis, primarily known from fragmentary material discovered by C.H. Sternberg in Alberta, Canada (the material that bore the name Troodon at that time were teeth initially assigned to a kind of lizard by Leidy and later identified to be from a theropod dinosaur, although not all scientists agreed on this until more material was discovered). Later, in 1969, Dale Russell found a more complete specimen that allowed Phil Currie to identify Stenonychosaurus as synonymous with Troodon in the late 1980’s, five years after the emergence of the Dinosauroid in the public sphere. As you can guess, however, it was Russell’s more complete Troodon that provided the basis for his speculation, primarily because it appeared to have a very large brain for its size, stereoscopic vision, and the first digit could have some sort of supporting role in grasping. Our problem, however, is determining just how significant each of these features are and if they really could have opened evolutionary paths up to Troodon unavailable to other dinosaurs.
The primary problem that I have with the Dinosauroid and other similar reconstructions is that it rests on the assumption that a level of intelligence on par with extant Homo sapiens would have evolved in one lineage or another if hominids never evolved. How can we be sure this is so? Let’s assume, just for a moment, that Troodon really did have the potential to evolve a level of intelligence within the range of Homo sapiens and survived the extinction event at the end of the Cretaceous; would they have survived for the next 65 million years, or at least long enough to evolve a greater level of intelligence? There are entire groups of mammals that evolved after the extinction of the dinosaurs (mesonychids, to name one) that became extinct, so our hypothetical Troodon would not have been free-and-clear during the Cenozoic. Indeed, allowing non-avian dinosaurs to survive the end of the Cretaceous would impact life on earth in ways that we cannot account for, and there would be no guarantee that the group would not go extinct sooner or later due to some other cause.
Given this aspect of contingency, it is difficult to be sure that anything in certain in evolution, especially when the origin of our own intelligence remains mysterious. Even if we were absolutely sure of what led to the evolution of our well-developed brains, our upright posture, and other characteristics of our species, other groups of animals would not be obliged to follow precisely the same path and there would always be uncertainty in our comparisons to the hypothetical intellectual creatures. Convergences do occur in evolution, surely, but most of the well-understood examples (i.e. body shapes of dolphins, sharks, and ichthyosaurs as adaptations to an wholly aquatic lifestyle) do not provide good templates for the evolution of intelligence. Indeed, there’s nothing in nature that suggests that Homo sapiens (or its equivalent) was somehow meant to be or would have evolved eventually; there is no goal or endpoint to the evolutionary process, and what is adaptive today might not be tomorrow. Stephen Jay Gould puts this more eloquently in an excerpt from his book Wonderful Life;
Life is a copiously branching bush, continually pruned by the grim reaper of extinction, not a ladder of predictable progress. Most people may know this as a phrase to be uttered, but not as a concept brought into the deep interior of understanding. Hence we continually make errors inspired by unconscious allegiance to the ladder of progress, even when we explicitly deny such a superannuated view of life.
As can be imagined, not everyone agrees with this view, and Simon Conway Morris has done much to speak out against the role of contingency in evolution. In a famous exchange in Natural History magazine about contingency in evolution and its relationship to the Burgess Shale, Morris wrote;
Contingency or no, I believe that a creature with intelligence and self-awareness on a level with our own would surely have evolved–although perhaps not from a tailless, upright ape. Almost any planet with life, in my view, will produce living creatures we would recognize as parallel in form and function to our own biota. But first, life must arise, and we have no idea how rare an event that might be. If we are honest, despite our exciting fancies about extraterrestrials, we must admit the real possibility that life arose but once, and that we are alone and unique in the cosmos–with an awesome and, to many, unanticipated role as stewards of all other living things. But were we to let evolution take another route than it did, why not grant (as, Gould will not) that another kind of being would have evolved to fill our special place in nature?
Morris’ view is even more shocking when it is realized that he isn’t just talking about intelligence, but the entire evolutionary history of life on earth. If we were to visit another planet that was host to living creatures for as long as ours, we would (in Morris’ view) be able to see extant organisms similar to those on our planet and dig up alien equivalents of dinosaurs, temnospondyls, and trilobites, life following the same evolutionary pathways as on Earth. This seems to assume that the planet on which life arose would be similar to our own, but I find it extremely presumptuous to say that life must have evolved in a manner parallel to Earth’s when extinction (especially mass or catastrophic extinction) has played an important role in determining what forms of life will be present on a planet during one time or another. Earth is a dynamic planet, changes occurring from the level of tidal pools to continental drift, and the only way to ensure an exact parallel of evolution on another planet would be to “replay the tape” in exactly the same way to an excruciating level of detail. Gould replied to Morris’ claims this way;
I am puzzled that Conway Morris apparently, doesn’t grasp the equally strong (and inevitable) personal preferences embedded in his own view of life–especially when he ends his commentary with the highly idiosyncratic argument that life might be unique to Earth in the cosmos, but that intelligence at a human level will predictably follow if life has arisen anywhere else. Most people, including me, would make the opposite argument based on usual interpretations of probability: The origin life seems reasonably predictable on planets of earthlike composition, while any particular pathway, including consciousness at our level, seems highly contingent and chancy.
I don’t know how else to interpret the cardinal fact that life did originate on earth almost as soon as environmental conditions permitted such an event–an indication, although surely not a proof, of reasonable expectation and predictability; whereas consciousness has evolved only once, and in a marginal lineage among so many million that have graced our planet’s history–an indication, although again not a proof, that such a phenomenon is not inevitably meant to be.
Could high levels of intelligence evolved in another lineage on earth if things were different (or on another planet, for that matter)? Absolutely, but such an outcome is not automatically deigned to be. Our own evolutionary history makes it plain that the mere possession of high levels of intelligence does not grant an organism a privileged position, free from threat of extinction, our past history making it clear that evolution produces a branching bush and not a straight line of ever more “fit” forms.
Extinction reveals the effect of contingency in evolution; why did so many of our evolutionary relatives, so close to us in form and mental ability, not survive? If we were to go back to the time when the chimpanzee lineage and the line leading to Homo split and started over again, would we have reached the same outcome? Would another relative of ours, perhaps Neanderthals, survived and developed in a similar way? This is a game of “What if?” that I have no answer to, but it seems clear that high levels of intelligence are allowed to evolve and are not an unavoidable consequence of the evolutionary process.
Returning to the subject of our friend the Dinosauroid, such reconstructions seem to reflect the sort of progression seen in the above illustration of horse evolution. It’s easy to pick what may seem like a suitable ancestor and bookend an arrow with a living descendant, but there is a lot of evolution in that arrow that is omitted. This illustration, for one, suggests that once Eohippus evolved it was on the fast track to becoming Equus, the transitions in-between like the growth in size and reduction of toes being intuitive, and it seems that the Dinosauroid is based upon the same sort of logic that largely disregards the way evolution works. In a way, such reconstructions even represent a kind of special pleading, not only implying the survival of a particular species but also clearing the evolutionary path for it to evolve in one way rather than another, in this case taking the form of a human. Even if we are to play along with this idea, would highly intelligent creatures converge on a humanoid body form (as Morris suggests)? Again, not necessarily, and there’s no reason to think that high levels of intelligence must be accompanied by an upright, bipedal stance, opposable thumbs, or an overly large braincase. As Darren Naish once wrote on this same topic;
The reason that we humans have the body shape that we do is not – I think – because it’s the ‘best’ body shape for a smart, big-brained biped to have, it is instead the result of our specific lineage’s evolutionary history. Given that, so far as we know, the humanoid body shape has evolved just once, we simply have no way of knowing whether it’s a particularly ‘good’ morphology or not. Furthermore, the humanoid body shape is not a prerequisite for the evolution of big brains given that brains proportionally as big as, or bigger than, those of hominids are found in some birds and fish (that’s right: humans do NOT have the proportionally biggest brains).
The morphology of Homo sapiens has some advantages (energy efficiency when walking long distances) and some drawbacks (convoluted, narrow birth canals and back pain/injuries), but I don’t think that we can objectively call it “good” or “bad,” either. Thinking that intelligent organisms must adhere to our shape does little except highlight the hubris that often goes into such considerations. I had mentioned before that the Dinosauroid has appeared more often in tabloid newspapers and alien internet forums than scientific papers, and this is primarily because it looks like the stereotypical alien, itself a sign of bias on the part of our own species. As Carl Sagan wrote in The Demon Haunted World;
The typical modern extraterrestrial reported in America in the ’80s and early 90’s is small, with disproportionately large head and eyes, undeveloped facial features, no visible eyebrows or genitals, and smooth gray skin. It looks to me eerily like a fetus in roughly the twelfth week of pregnancy, or a starving child. Why so many of us might be obsessing on fetuses and malnourished children, and imagining them attacking or sexually manipulating us, is an interesting question.
…the UFO abduction syndrome portrays, it seems to me, a banal Universe. The form of the supposed aliens is marked by a failure of the imagination and a preoccupation with human concerns. Not a single being presented in all these accounts is as astonishing as a cockatoo would be if you had never before beheld a bird. Any protozoology or bacteriology or mycology textbook is filled with wonders that far outshine the most exotic descriptions of the alien abductionists. The believers take the common elements in their stories as tokens of verisimilitude, rather than as evidence that they have contrived their stories out of shared culture and biology.
Oddly enough, it is often birds, the descendants of dinosaurs, that often show us that animals with high levels of intelligence do not have to be upright apes, or even primates. Alex the African Grey Parrot (who recently passed away) possessed extraordinary cognitive abilities, and it has long been known that members of the Family Corvidae (i.e. crows) are extremely intelligent, having brain sizes comparable to that of chimpanzees, dolphins, and humans. Even in turning to non-human primates, Capuchin monkeys have brain-to-body size ratios on par with those of chimpanzees, the New World Monkeys proving to be very intelligent even though they might not be immediately recognized as such as they are arboreal quadrupeds and not apes. Truly, the more animal cognition and intelligence is studied it seems that some have minds that are far closer to our own than we acknowledged previously.
Finally, this brings us to the birds. Troodon was closely related to birds and likely had feathers, but by the time it existed in the Late Cretaceous there were already avians in the air. Even if Troodon survived, would birds have developed higher levels of intelligence first? What if both dinosaur and avian did? It is clear from living species that many birds have high levels of intelligence, however, and so we can say that dinosaurs did evolve high levels of intelligence but look nothing like Homo sapiens, refuting the Dinosauroid model. This becomes immediately apparent when we stop considering ourselves as privileged or superior to other forms of life on this planet, leaving us no reason to think that there is some universal constraint that only also primate-like organisms to achieve intellectual prowess.
At this point I should probably mention the fantastic artwork of Nemo Ramjet, an artist who’s Dinosauroids are probably more accurate when considering if dinosaurs were able to evolve higher levels of intelligence. As I’ve attempted to make clear in this post, however, there’s no reason to believe that given a reprieve from extinction at the end of the Cretaceous non-avian dinosaurs would have evolved in such a manner at all (Dougal Dixon’s The New Dinosaurs springs to mind here, although it’s guilty of supposing fine-tuned convergence in many cases, as well), such a change in history having no set outcome and still being subject to contingency. The extinction of so many of our own evolutionary relatives like Paranthropus show that intelligence does not provide an evolutionary free ride or have inevitable consequences, making the development of intelligence all that more special and rare. As fulfilling or enjoyable as it may be to construct evolutionary narratives to elucidate how evolution made us what we are, we should not attribute the role of “Mother Nature” to evolution; nature neither cares for us or despises us, and it is that fact that makes our present condition all the more spectacular and valuable.
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