For whatever reason, Boen demanded a Kindle Unlimited subscription. We signed up for 2 months, so I might as well use it. I checked out The Rise and Reign of the Mammals. This is an unexpectedly great read. Just the pictures alone illustrating the evolution of whales from a 4 legged land animal to the leviathan of the ocean is well worth the read. What's even better is that Steve Brusatte's text evokes the sense of wonder that adults too often lose as a result of too much adulting:
The blue whale is the most extreme of these “extreme mammals.” It is not merely the largest mammal alive today, but the largest living animal, period. Nobody has ever found a fossil of anything bigger, which means that the blue whale is the all-time record holder, the heavyweight champion of the history of the world. It’s a simple but profound statement that bears repeating: the biggest animal that has ever lived is alive right now. Of all the billions of species that have lived during the billions of years of Earth history, we are among the privileged few that can say such a thing. How glorious is it that we breathe the same air as a blue whale, swim in the same waters, and gaze at the same stars? Blue whale mothers birth three-ton calves the length of a speedboat, which bulk up by about fifteen tons during their half year of nursing. Adults can dive to depths of more than 1,000 feet (315 meters) and hold their breath for well more than an hour and expel a two-story column of water from their blowhole when they come up for air. With one gulp of their expandable mouths, they can take in a backyard swimming pool’s worth of water, which they do several times a day, in order to gather the two tons of krill—little shrimpy crustaceans—they need to power their metabolism. They’re smart and social, and their low-pitch vocalizations are the most powerful sound in the animal kingdom, able to reverberate for over nine hundred miles through the abyss. But all is not well. It is estimated that 99 percent of the blue whale population was exterminated by whaling over the past couple of centuries. Of a community that once numbered in the hundreds of thousands at any given time, only a few tens of thousands of individuals—at most—remain. (kindle loc 3122-3135)
It is books like these that made me want to become a scientist, all those years ago, and it's sad that we live in a post-literate society, where books like these aren't common reading amongst children.
I love the questions and answers posed by this book, such as the exploration of what delineates a mammal. When I was a kid, the textbooks talked about the definition of mammals as being creatures that gave birth live (not true it turned out --- the platypus lays eggs), fed its young milk (true, but it turned out that this feature arose late), was warm blooded (also a relatively late development). The book traces the evolutionary development and points out that the development of a jaw that could pulverize leaves and plant matter (thereby starting digestion early in the food intake process) was when the split happened. What's even more interesting is the evolution of the earbones in mammals!
The ring, hammer, anvil, and stirrup enable one of the most advanced neurosensory skills of mammals: our ability to hear a wide range of sounds, particularly high-frequency ones. Birds, reptiles, and amphibians can all hear. They can all take sound waves and convert them to liquid waves in their cochleas. But they can’t hear anywhere near as well as mammals, and across such a wide range of frequencies, because they have only a single ear bone to do it all—the stapes, the equivalent to the stirrup. (kindle loc 1473)
Other questions addressed include why land mammals never became as big as dinosaurs:
Why didn’t land mammals get as big as dinosaurs? As huge as they were, Palaeoloxodon and Paraceratherium were still not even half as heavy as the most enormous long-necked dinosaurs. There’s no easy answer to this conundrum, but I suspect it has to do with the lungs. Mammal lungs are tidal; breaths go in and out, as the lung expands and contracts. We feel this every time our chest goes up and down as we breathe. Birds are different: they have a flow-through lung, as air can go through it in only one direction. This feat of engineering is choreographed by balloonlike air sacs, which connect to the lung and funnel air through it in a precise sequence. When a bird breathes in, some of the oxygen-rich air goes directly across the lungs, while the rest is shunted into the air sacs. Then, when the air sacs contract, the still-oxygenated air inside is passed across the lung during exhalation, meaning birds—and the giant dinosaurs with the same lungs—take in oxygen while breathing in and out. This means dinosaurs got more oxygen with each breath than a similarly sized mammal. And there’s more: the air sacs extend through the body and even into the bones, acting as an air-conditioning system, and lightening the skeleton. The end result: large dinosaurs were more efficient breathers, could cool their bodies easier, and had lighter and more limber skeletons. This, I think, is why no land mammal has been able to approach their titanic sizes. (kindle loc 3268)
What this book illustrates is how modern science is inter-disciplinary. The research crosses paleontology, genetics (DNA analysis was what allowed the origin of whales to be determined), geology/earth sciences, and climate science and ties everything together to form a coherent story about the evolution of mammals. The book also covers the location of many fossils and may give you a reason to visit what you used to have considered flyover country. Even something as mundane as teeth in grass grazing animals is explored in detail:
Because grasses grow near to the ground in wide open spaces, they are a magnet for dirt, dust, and other windblown particles. Many grazing mammals today ingest an unholy amount of grit as they nibble. On average, domestic cattle swallow about 4–6 percent dirt, compared to less than 2 percent for leaf-eating browsers. Sheep, which crop grass closer to the ground than cows, have it worse: in New Zealand, they have been observed to consume 33 percent dirt—in other words, one ounce of dirt for every two ounces of grass. The dirt and phytoliths function as sandpaper, filing down the teeth of grazing mammals as they eat. This is not a trivial concern: grazers today lose about three millimeters of tooth every year, the enamel literally scoured away. That might not sound like much, but consider this. My molar teeth are about a centimeter (ten millimeters) tall above the gum line. If I ate nothing but grass, my teeth would barely last three years. (kindle loc 3860)
My one criticism of this book (and I suspect one reason I will find it tough to make my kids read the book) is that it spends a lot of time giving credit (and telling the story) of the various scientists that the author knew and interviewed and interacted with. I understand the intention and the respect the author has for these scientists (who were frequently his colleagues, mentors, students, and friends!) but frequently these vignettes disrupt the evolutionary/scientific story he's telling and caused me to want to skip pages in impatience to get to the good parts. That the book has so many good parts (and I've only covered a few of them --- there's so much more --- go read the book!) means it's worth it to bear with those sections. After all, some of these stories might inspire a kid reading this book to go on to become a scientist!
Needless to say this book comes highly recommended and is likely to be my recommendation for the book of the year!
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