From our long lives to our social skills and even language, zoologist Antone Martinho-Truswell argues that we are more like birds than we think
9 March 2022
EVOLUTION has created a living world of jaw-dropping diversity. It has also generated what seem like astonishing coincidences. The pangolins of Africa and armadillos of South America, for instance, look like close cousins. In fact, each is more closely related to humans than to each other. Their similarity arises because they independently evolved near-identical strategies to cope with the same kind of environmental challenges.
This is just one example of what is known as convergent evolution, but there are many others, and not all of them are so easy to spot. Take humans and birds: few readers will be immediately won over by Sydney-based zoologist Antone Martinho-Truswell’s claims that we are “like a strangely featherless bird”, and that we have more in common with birds than with our mammalian cousins.
By the time I finished The Parrot in the Mirror, though, I found that idea both compelling and reasonable. Martinho-Truswell explores the traits shared by humans and birds, from our unusual longevity to our advanced social skills, from our parenting styles to our intelligence and even the use of language. These, he argues, are all examples of convergent evolution.
Briefly, his argument goes like this: once birds could fly, they could elude almost all predators. Since they were now less likely to be eaten in any given year, they could live longer and produce more offspring. With longevity came the opportunity and the need to develop increased intelligence. It is an advantage for long-living animals to be smart because it helps them to survive long enough to raise their young to adulthood. What’s more, because longer development requires a bigger egg and a bigger yolk sac, and because an egg can only get so big if its mother is to fly, most birds hatch out very immature, helpless young. Chicks require enormous amounts of care, often provided by pair-bonded parents, and sometimes supplemented by a larger community. This favours the evolution of complex social behaviour and communication.
Martinho-Truswell argues that the human evolutionary story is a warped mirror image of this. Our story begins, not with flight, but with communal behaviour among primates, which promoted the evolution of intelligence and social behaviour. This reduced the likelihood of predation, and longevity followed, boosting intelligence to the point where big-brained human young have to be born immature and helpless so as not to endanger their mothers’ lives during childbirth.
So, the argument goes, humans and birds evolved measurable intelligence in response to similar challenges. But how do we compare our abilities?
In this regard, Martinho-Truswell does well to strike a balance between precision and imagination. On the one hand, a duckling’s ability to identify its mother shortly after the moment of its birth puts it well ahead of chimpanzees, parrots, pigeons, crows and even human children. But this one hardwired ability doesn’t necessarily make the duckling more intelligent.
“Humans and birds evolved intelligence in response to similar challenges. But how do we compare abilities?”
On the other hand, it would be a dull observer indeed that didn’t see quite staggering evidence of advanced cognition in Irene Pepperberg’s 30-year study of language use in Alex, an African grey parrot. The bird not only answered questions, he asked them, too. And he got annoyed if people gave him silly answers.
Containing the complexities of convergent evolution in a straightforward narrative isn’t easy. Evolutionary causes and effects don’t follow each other in neat, storybook fashion, and there is always the temptation, reading this book, to take Martinho-Truswell’s acts of narrative shorthand at face value and suppose that humans, 50 million years behind parrots in the evolution of intelligence, somehow became more human by actually mimicking their distant avian cousins.
Clearly that isn’t the case. But perhaps it is better to be slightly misled by a gripping story than to be bludgeoned by a dull one. Martinho-Truswell has written a superb introduction to a surprisingly complex field of study. Having read it, you won’t look at yourself in the mirror in quite the same way.
More on these topics: