Everyone loves dinosaurs. Last weekend, when my son Edward and I were in New York City to go to the opera, given a couple of free hours in the afternoon, he headed out to the Museum of Natural History to gaze again at those monsters of the past. As I discovered on a trip last year to the Creationist Museum in Kentucky, even the biblical literalists are fascinated by these long-gone behemoths. One of my favorite cartoons explaining their demise 65 million years ago shows two dinos stranded forlornly on an islet in the middle of an ocean. They are looking at Noah’s Ark floating away and the one turns to the other and says: “Oh crap! Was that today?”
The dinosaurs are back in the news. Because they are the ancestors of the birds, we have long known that some of them had to be feathered. Where you draw the line is almost a matter of taste, but it is clear that just above you are going to find dinosaurs with bird-like features, notably feathers, and just below you are going to find birds with dinosaur-like features, such as teeth.
Why precisely there are feathers seems still to be a matter of debate. It seems pretty clear that the feathers came first and then flight. Perhaps the feathers were for insulation, or possibly for catching insects or whatever. An interesting question is whether or not the feathers would be colored — whether any of the dinosaurs were colored for that matter. Looking at today’s animals and plants — at today’s reptiles (for remember that the dinos were reptiles) — you would expect color in the right circumstances. What do I mean by that? Well, Darwin’s theory of evolution through natural selection — still the dominant paradigm folks, no matter what you read elsewhere — tells us that organisms have features, adaptations, that help them to survive and reproduce. Eyes, teeth, vaginas, penises, bark, leaves, roots — you name it, it’s there for a purpose. If color is going to help an organism, then it will be colored. If not, then not.
In a way, being drab is the default position. Although mammals only really came into their own with the end of the dinosaurs, they were around as long as the dinos, perhaps from a couple of hundred million years ago. For most of their existence, they were nocturnal and small and it paid to be inconspicuous. One suspects that most of the early mammals were pretty good at blending into the twilight in the undergrowth. However there are good biological reasons why sometimes color is the way to go — very much the way to go as we see from some of today’s brightly colored birds and fish and (sometimes) reptiles and mammals.
Sexual selection is the most obvious reason. One sex is showing off and trying to attract members of the other sex. Usually it is the males who are performing, but sometimes the roles are reversed and it is the females who are the gaudy ones. This is common in some kinds of fish. There are other reasons for color and many of these are collected and discussed in a fascinating new book, Dazzled and Deceived: Mimicry and Camouflage (Yale University Press) by English science writer Peter Forbes. Looking mainly (although not exclusively) at insects, Forbes shows how sometimes color is used as a warning. “I taste bloody awful! Stay away!” Of course, this is hard cheese on those who are eaten before the predators learn this, but the rest of the group (especially your relatives) benefits mightily. As soon as something like this is in place, then along come other species that cheat by riding on the backs of the originally colored, nasty-tasting specimens. Even if they do not themselves taste nasty, natural selection can give them mimicking bright colors so that predators think that they are nasty and avoid them.
This incidentally is known as “Batesian mimicry,” after Henry Walter Bates. He was a Victorian naturalist who went to the Amazon with Alfred Russel Wallace, the man who co-discovered natural selection along with Charles Darwin. Bates found that some Amazonian butterflies are very brightly colored but avoided by the birds, and then to his astonishment found that other butterflies mimic these models. In one of the triumphs of 19th-century natural history, he worked out in detail how the original butterflies taste horrible and how the mimics freeload on their backs, as it were. It is nice to be able to report how Darwin was very appreciative of Bates’s work, putting the details into later editions of the Origin of Species, and finding Bates — who came from a humble background — fulltime work as secretary to the Royal Geographical Society.
As Forbes tells it, there is much more to the color story than this. Most fascinating is how the ornithologists and lepidopterists — the folk most interested in animal color — went to war. In both the First and the Second World Wars, camouflage and deception were of vital importance. As happens with these things, at first the politicians and the military authorities thought that it was all a matter of common sense and it took a huge amount of yelling and whining for the experts in the field to get a hearing. But in the end they did and were appreciated. In the battle of El Alamein, for instance, General Montgomery made full use of the techniques the naturalists taught him. Most fascinating perhaps is the story of “dazzle” where the naturalists persuaded the navies to paint their ships in striking geometrical designs, in order to confuse attackers about distances and directions. (There is a great tie-in here with art styles and the coming of Cubism.)
And so back to the dinosaurs. Thanks to some brilliant recent work, it turns out that the feathered dinos were incredibly brightly marked. They had vibrant patterns and colors rarely seen outside tropical birds today. Scientists have chipped off little bits from dinosaur fossils and discovered pigments which can then be used to reconstitute the original colors and markings. The results are simply stunning.
Of course, what is great about this — what is great about a science like evolutionary biology — is that this is just the beginning. Creationists often complain about the unsolved puzzles in the evolutionary story. What they don’t realize is that great science starts in the morning with a problem, solves it by lunchtime, and then has two more problems by the end of the day. Good scientists don’t want to spend their days polishing the theories of the past. They want to get on with the job themselves. In the dino, colored-feather case, now the problem is of finding out just why the colors were as they were. Were they for sexual attraction? Were they warning devices? Were they for deception? Stay tuned. This is where the action is and this is why it is not just wrong but downright pathetic to deny our children the teaching of evolution in the classrooms of the nation.Return to Top