Beasts Before Us: The Untold Story of Mammal Origins and Evolution

Beasts Before Us: The Untold Story of Mammal Origins and Evolution by Elsa Panciroli

Let’s face it. When it comes to discussion and portrayal of ancient/extinct life in modern culture, dinosaurs rule. They rumble, lumber, sprint, pounce, trumpet, and roar across our screens and pages, across bedspreads and pajamas. Their names trip merrily across the tongues of children as they reel off Latinate terminology and eras like an auctioneer at a livestock sale. The “Rex” in T-rex may as well refer to the King of the Lizard’s place in our collective minds as much to its role as an apex predator of its time.

Pity then the poor early mammals, who can’t help but be overshadowed (literally and figuratively) by their massive cousins. Well, no more. Paleontologist Elsa Panciroli speaks for the mammals! And luckily for us, she does so in fantastic fashion. In sharp, concise, vivid prose, she’s here to tell us to forget everything we think we know about early mammals, because it’s probably wrong. No, they didn’t evolve from reptiles, or even mammal-like reptiles (a phrase she loathes and hopes to drive into oblivion). No, they didn’t simply cower as the dinos were active (some early mammals actually preyed on dinosaurs). No, they didn’t only become players when the dinosaurs all disappeared. It all makes for a fascinating and eye-opening read, and though I don’t think Panciroli is going to help early mammals dethrone dinosaurs from their lofty perch, I do think she gets them into the room. Where they should have been all along.

As one would expect, Beasts Before Us: The Untold Story of Mammal Origins and Evolution (2021) is mostly structured chronologically, in linear fashion. But, and Panciroli is smart to not only note this point but repeat it throughout, evolution itself is not linear, it is not “progress” from A to B to C. Nor, she is equally at pains to emphasize, does it have a purpose of “improvement.” She is well aware of the lure of that view — “it is, of course, easy to slip into language that suggests evolution had a goal” — but strongly dispels the mirage — “There is no end-goal to evolution’s journey. It is random, the route is based on happenstance.”

With that admonition front and center, Panciroli begins way back with the first colonization of land, well before dinosaurs or mammals, then moves through until “we hit the mammal highway around 300 million years ago.” It’s here that Panciroli’s enthusiasm really begins to shine as she details the many early innovations, such as sabre teeth and arboreal adaptation. Unfortunately, “the beasts that flourished in the first age of mammals were … swept away in a mass extinction event so brutal that life on Earth came closer to annihilation than ever before or since” (estimates of 85% of all life).

From the Permian we shift to the Mesozoic (made up of the Triassic, Jurassic, and Cretaceous Periods), when reptiles, and especially dinosaurs, became dominant. Mammals, meanwhile, got small, with none in the Late Triassic weighing more than a few hundred grams. They also became nocturnal (a shift still seen in the makeup of our eyes) even as jawbones shifted, and the mammalian ear formed (those two are linked). By the middle Jurassic, counter to what earlier paleontologists had thought, mammals were flourishing, radiating outward, and adapting to all sorts of niches, especially with the rise of flowering plants in the Cretaceous. But then an indifferent universe intervened again, this time via the Chicxulub impact. According to earlier scientists, the extinction of the dinosaurs is what “freed” the mammals to finally come into their own, but one of the more fascinating insights of Beasts Before Us is Panciroli’s theory (well-supported) that, in fact, “it was probably not the dinosaurs who kept our ancestors in check, but their mammal brothers and sisters.”

Dr Elsa Panciroli

After this it’s a relatively quick hop, skip, and jump over the next few million years, with Panciroli stopping before the rise of hominids, or as she puts it, “our journey ends where most other mammal origin stories only just begin.” She does, however, note our impact on current life (the Sixth Great Extinction) as well as on the monotone nature of that life, pointing out that “Around 60 percent of all mammals alive today are kept by humans for food.” Throw in ourselves and our pets, and “wild mammals represent only 4 percent of all mammals alive today.”

Panciroli covers a plethora of species and details a host of anatomical differences and changes — bone structure, herbivore stomachs, ectothermic metabolism, etc. To be honest, the scientific names can get overwhelming and hard to remember, but outside of that inconsequential bit, the text is always crystal clear as it lays out evolutionary changes and what problems they solved. The lucid prose is aided with a number of illustrations so readers can better visualize what is being described. Panciroli also has a deft hand with metaphors/analogies, which are often richly vivid, sometimes humorous, never overly complicated, and always clarifying. In describing the Mesozoic reptiles taking advantage of the newly-emptied world, she writes that “like teenagers leaving home for the first time, they started to experiment.” Later she portrays survivors of an extinction event “striding out of the flames like unkillable-Terminators.” And before then, she says of the early nocturnal mammals with their newly powerful bite and bigger brains, “These tiny ancestors were living microchips. They were night vision goggles. They were fuzzy little ninjas.”

Along with the hard science and detailed anatomy, Panciroli intersperses her own experiences at various sites around the world, digging in Scotland, for instance, or using high-tech machines in France to get unprecedented looks at bones. She also highlights two major issues in not just paleontology but all science nowadays. One is the imperialistic roots of so much science, which was also intertwined with racism and misogyny. Its “language of conquest” she argues, “still permeates how we talk about evolution … How tedious it is always talking about the rise and fall of life as though it were a series of oppressive empires.” She rightfully argues for the “decolonization” of science, the repatriation of fossils, the current day diversification of the academic disciplines (in terms of race, gender, international regions), and the long-overdue recognition of contributions from women and indigenous people. She herself spends a good portion of the book highlighting the exploits and achievements of Zofia Kielan-Jaworoswka, who “transformed Mesozoic mammal research [and yet] remains one of the many under-acknowledged women of scientific history.”

Beasts Before Us: The Untold Story of Mammal Origins and Evolution is not only an excellent example of popular science — lucid, vivid, colorful, engaging, informative, personal — but it’s also that rare non-fiction book that opens up a whole new world, one not already explored by a number of other authors. I don’t love my dinosaurs any less, or my megafauna late mammals like Smilodon or the giant sloth, but I think I do need to nudge my models (yes, I have models) aside to make room on my shelf for some of the fascinating creatures Panciroli introduces here. Maybe one of those “fuzzy ninjas …”