快猫短视频

Steve Brusatte

Picador

ANYONE writing about mammals faces a key challenge: not making it about us. Humans are mammals of course, and it is easy to present the tale of mammalian evolution as inexorably leading to our arrival. Palaeontologist Steve Brusatte deftly avoids this problem in his new history of mammals by leaving almost all mention of humans to the final pages, where we come in as, essentially, a peculiar and rather alarming twist in the tale.

Brusatte is most famous for his work on dinosaurs. His previous book, The Rise and Fall of the Dinosaurs, was a widely praised bestseller. In recent years, he has expanded his research into other areas, and The Rise and Reign of the Mammals is the result.

The evolutionary origin of mammals is a complex story, involving technical terms such as 鈥渕ammaliaform鈥� 鈥� meaning 鈥渁n animal that is almost a mammal but not quite鈥�. Worse still, many of these kinds of animal are now extinct, with no modern equivalent to help us understand them. To Brusatte鈥檚 credit, his discussion of the emergence of mammals remains startlingly clear and engaging.

For instance, the synapsids come to life as a group of reptile- like animals that, to an inexperienced eye, might be mistaken for oversized geckos or primitive dinosaurs. But in fact, they had distinctive skulls that enabled them to grow powerful jaw muscles for chomping on tough insects 鈥� a trait that would be carried through to their mammalian descendants. The most famous synapsid is Dimetrodon, which had a huge sail on its back, but there were many others and they dominated land ecosystems for millions of years.

Brusatte is particularly good on how we draw the line between mammals and non-mammals. He acknowledges that on some level it is an arbitrary distinction, created to help make sense of a complex world. But he still offers a sensible answer.

At this point, the story would normally cover how the tiny mammals lived in the shadow of the huge dinosaurs for millions of years. Brusatte engages hard with this clich茅, arguing that competition actually went both ways: mammals couldn鈥檛 grow very large with the dinosaurs around, but dinosaurs couldn鈥檛 get very small because mammals were much better at carving out a niche at that size.

He shows a similarly deft touch when handling the mass extinction of 66 million years ago that wiped out all the dinosaurs except birds. It is true that mammals survived, but Brusatte shows that it wasn鈥檛 an easy escape. Instead, he emphasises how much of a hit the mammals took, with three out of four species disappearing in one heavily studied region. Mammals, writes Brusatte, had many little advantages that helped them to scrape through, including being small and adapted for a generalist diet.

The story ends with the primates, the group that includes humans. However, Brusatte鈥檚 focus here is on non-human primates, exploring the earliest primates that emerged soon after the dinosaur extinction and following their monkey and ape descendants up to the present. When Homo sapiens turns up, it is presented as something of a calamity: our hunting prowess wipes out many mammal species, and our hominin cousins such as Neanderthals die out as well.

Plenty of writers have tackled mammalian biology, but The Rise and Reign of the Mammals stands out for its brilliant balance of scientific detail and lively, efficient storytelling. Brusatte has a clear understanding of the book he is writing. It isn鈥檛 a long argument, like On the Origin of Species, but rather a story, which he tells with elan.