THE delight is in the detail of a new evolutionary history of birds, as is some of the devilry – for this isn’t a light read. Douglas Futuyma is out to tell a double tale: he explains how the study of these animals advanced our understanding of evolution and he shows how advances in evolutionary science solve some long-standing ornithological mysteries, even as they expose others.
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Futuyma has written How Birds Evolve: What science reveals about their origin, lives, and diversity for birders, and being a birder himself (he began bird-spotting around the age of 11 in New York’s public parks), he knows how fiercely the bug can bite. Many birders are halfway to being field scientists already, and a lot of celebrated practitioners of field work, such as Ernst Mayr, Konrad Lorenz and Niko Tinbergen, have been birders.
“I suspect few of my teachers in the 1960s imagined that we would be studying birds by combining information from geology and molecular biology – disciplines that are miles apart,” writes Futuyma, giving readers an early hint of the complexities to come.
Birds, he reminds us, are both a curious and curiously productive field of study for evolutionary biologists. They are less useful in understanding the mechanisms of evolution than insects, plants and bacteria because they don’t reproduce as quickly, but, being various and everywhere, they are vital to the study of behaviour, longevity, ecology, speciation, cultural evolution and a host of other things.
The ability to study bird populations and how they interact gave evolutionary biologists a foretaste of what their science would become. “The models of how variation might persist,” Futuyma writes, “were developed by evolutionary biologists who might not have known a hawk from a handsaw, but were adept in mathematics.”
Applying lessons from birds to ourselves, though risky, has also proved irresistible, and, at least in evolutionary science’s early days, very useful. In pondering human evolution, Charles Darwin developed the idea of sexual selection, which takes up more than half of his The Descent of Man of 1871. “Darwin devotes four full chapters to birds and cites at least 170 species,” Futuyma points out. “Birds provided more evidence for his ideas about sexual selection than any other group of animals.”
To grapple with bird diversity, one pretty much has to conjure up an idea of evolution. Peculiar and apparently useless features abound in the avian world, a sure sign of unceasing adaptation. To complicate matters, there are also many instances of convergent evolution. Feathers may have evolved only once, and through a bizarre genetic accident at that.
Feather and wing shapes, however, recur again and again in even distantly related species. As Futuyma reminds us, Darwin once predicted that our classifications “will come to be, as far as they can be so made, genealogies”, but even his credulity would have been stretched by news that flamingoes are very closely related to grebes.
Futuyma unpacks the story of evolutionary science alongside the story of how birds evolved, acquiring bipedal locomotion and simple filamentous feathers as Dinosauria, then clavicles fused into a wishbone in Theropoda, on and on, until we arrive at what we might as well call the modern bird, with its large, keeled breastbone, rapid growth and unfeasibly lightweight construction.
How Birds Evolve isn’t meant as an introduction to birds, much as readers of 91av might lap one up, but it is entertaining and passionate. Futuyma, an evolutionary biologist who is the author of textbooks on the subject, is out to inspire, and his new offering more than makes up in sheer wonder what it might lack in an easy and seductive narrative.
Simon Ings is 91av’s film columnist
