Tag Archives: convergent evolution

Anything but a safe bet

Posted on by

Reading The Gambling Animal: Humanity’s evolutionary winning streak—and how we risk it all by Glenn Harrison and Don Ross. For New Scientist, 29 January 2025

Insights into animal evolution used to come from studying a creature’s evolutionary relationships to its closest relatives. To lampoon the idea slightly: we once saw human beings as a kind of chimp.

Our perspectives have widened: looking across entire ecosystems, we begin to see what drives animals who share the same environment toward similar survival solutions. This is convergent evolution — the process by which, say, if you’re a vertebrate living in an aquaeous medium, you’re almost certainly going to end up looking like a fish.

Economists Glenn Harrison and Don Ross look at this process from an even further remove: they study evolution in terms of risks to a species’ survival, and trace the ways animals evolve to mitigate those risks. From this distance, it makes more sense to talk about communities and societies, than about individuals.

We used to understand social behaviour as the expression of intelligence, and that intelligence was rather simplistically conceived. Social animals thought at least a little bit “like us”. Of course this was never more than hand-waving in the absence of good data. Now Harrison and Ross arrive with good news from their research station amid the grasslands of South Africa: they’ve worked out how elephants think, why they never forget (the old saw is true), and why Pleistocene elephants and humans both acquired such huge and peculiar brains. their encephalisation suggests they co-evolved a neurological solution to the climate’s growing unpredictability. Faced with a landscape that was rapidly drying out, they both learned how to gamble on the likely location of future resources.

But while humans developed an overgrown frontal cortex, and learned to imagine, elephants overgrew their cerebellum. and learned to remember. For most of evolutionary history, the elephants were more successful than the hominins. Only recently has our borderline-delusional thinking allowed us to outcompete the once ubiquitous elephant.

Harrison and Ross are out to write a dense, complex, closely argued exposition of their risk-and-reward experiments with humans and elephants, and to discuss the evolutionary implications of this work. They are not writing a work of literature. It may take a chapter or two for the casual reader to settle to their meticulous style. Treats lie in store for those who stay patient. Not the least of them is a mischievously conceived “science fiction”, laying out exactly what elephant scientists in some wildly alternate Earth might make of those desperately challenged and almost-extinct humans, struggling out there in the veldt. The point is not merely to have fun (although the authors’ intellectual exuberance is clear); the authors are out to describe the workings of a complex but fundamentally non-human intelligence: a mind that weighs probabilities far more easily than it dreams up might-bes and nice-to-haves.

How does a mind that can’t remember more than seven numbers for more than five minutes still arrive at a decent scientific understanding of the world? The authors cheerfully admit that, having worked for so long with elephants, they find humans ever more baffling.

Tracing the way human societies evolved to manage risk, from the savannah to Wall Street, the authors note that while human individuals are mildly risk-averse, they innovate behavioral norms — and from those norms, institutions — that collectivise risk with astonishing effectiveness. The (possibly terminal) flowering of this ability may be the the concept of limited liability, pioneered in New York State in 1811, which has turbocharged the species’ runaway growth “across multiple dimensions, particularly of population and per-capita wealth.” However much you and I might fear the future, the institutions we have built are free to take the most horrible chances — not least, in recent decades, with the climate.

Human-style thnking is an unbelievably high-risk strategy that has paid off only because humans have enjoyed a quite incredible evolutionary winning streak. But past performance is no guarantee of future returns, and the authors are far from optimistic about our prospects: “The history of humans,” they suggest, “is not a record of safe bets.”

Not quite a coincidence

Posted on by

Reading Antone Martinho-Truswell’s The Parrot in the Mirror for New Scientist, 9 March 2022

Organisms adapt over evolutionary time to their changing surroundings. This creates, over time, a living world of quite jaw-dropping diversity. It also generates some astonishing coincidences — if “coincidence” is quite the right word to describe how two quite unlike species, adapting to identical environments, end up looking and behaving the same. For instance, the pangolins of Africa and the armadilloes of South America look like close cousins; in fact they’re more closely related to humans than they are to each other.

Convergent evolution doesn’t have to be so visually obvious. Take humans and birds: few readers will take on trust Sydney-based zoologist Martinho-Truswell’s assertion that we “look like a strangely featherless bird”.

By the time I finished The Parrot in the Mirror, though, I found that image 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 our use of language. These, the author argues, are all extraordinary examples of convergent evolution at work.

Crudely, Martinho-Truswell’s argument goes like this:

Once birds could fly, they could elude almost all predators. And since they were unlikely to be eaten in any given year, it made sense for birds to go on living, producing more eggs and offspring. Increased longevity followed. With longevity came increased intelligence. Long-living animals need to be smart because they get to be the parents of young who develop over a longer period. And because longer development requires a bigger egg and a bigger yolk sac, and because an egg can only get so big, most birds hatch out very immature, helpless young, that require enormous amounts of care. This care is provided by pair bonded parents, sometimes supplemented by a larger community, hence the evolution of complex social behaviour and language (or song, at any rate).

The human story is a twisted mirror-image of the avian one. Communal behaviour among primates promoted the evolution of intelligence, and this reduced the likelihood of predation. Longevity followed, boosting intelligence further, to the point where big-brained human young have to be born immature and helpless so as not to kill their mothers in childbirth.

For different reasons, then, humans and birds evolved measurable intelligence. But how do we compare our abilities? Can we even talk about bird smarts and human smarts in the same sentence?

Martinho-Truswell’s handling of this subject is very well done. A balance has to be stuck between precision and imagination. On the one hand, a duckling’s ability to imprint upon 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. On the other hand, it would be a dull observer indeed that did not see in Irene Pepperberg’s thirty-year study of language use in Alex, an African Grey parrot, quite staggering evidence of advanced cognition. (Alex not only asked questions; it asked them, and got annoyed if people offered dumb responses.)

Containing the niceties of convergent evolution in a straightforward narrative is not easy. Evolutionary causes and effects do not follow each other in neat, storybook fashion, and there’s 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. (Distant cousins indeed, by the way: the last common ancestor of birds and mammals died out 320 million years ago.)

But it is surely better to be very 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 and fraught field of study. Having read it, you will not look at yourself in the mirror in quite the same way.