## Metadata - Author: [[Elizabeth Kolbert]] - Full Title: The Sixth Extinction - Category: #books ## Highlights - “I sought a career in herpetology because I enjoy working with animals,” Joseph Mendelson, a herpetologist at Zoo Atlanta, has written. “I did not anticipate that it would come to resemble paleontology.” ([Location 259](https://readwise.io/to_kindle?action=open&asin=B00EGJE4G2&location=259)) - (Female African clawed frogs, when injected with the urine of a pregnant woman, lay eggs within a few hours.) ([Location 273](https://readwise.io/to_kindle?action=open&asin=B00EGJE4G2&location=273)) - a hundred million years from now, all that we consider to be the great works of man—the sculptures and the libraries, the monuments and the museums, the cities and the factories—will be compressed into a layer of sediment not much thicker than a cigarette paper. ([Location 1489](https://readwise.io/to_kindle?action=open&asin=B00EGJE4G2&location=1489)) - Tropical waters tend to be low in nutrients, like nitrogen and phosphorus, which are crucial to most forms of life. (This has to do with what’s called the thermal structure of the water column, and it’s why tropical waters are often so beautifully clear.) As a consequence, the seas in the tropics should be barren—the aqueous equivalent of deserts. Reefs are thus not just underwater rainforests; they are rainforests in a marine Sahara. ([Location 1982](https://readwise.io/to_kindle?action=open&asin=B00EGJE4G2&location=1982)) - Reefs—or, really, reef creatures—have developed a fantastically efficient system by which nutrients are passed from one class of organisms to another, as at a giant bazaar. Corals are the main players in this complex system of exchange, and, at the same time, they provide the platform that makes the trading possible. Without them, there’s just more watery desert. ([Location 1986](https://readwise.io/to_kindle?action=open&asin=B00EGJE4G2&location=1986)) - Tropical reefs need warmth, but when water temperatures rise too high, trouble ensues. The reasons for this have to do with the fact that reef-building corals lead double lives. Each individual polyp is an animal and, at the same time, a host for microscopic plants known as zooxanthellae. The zooxanthellae produce carbohydrates, via photosynthesis, and the polyps harvest these carbohydrates, much as farmers harvest corn. Once water temperatures rise past a certain point—that temperature varies by location and also by species—the symbiotic relation between the corals and their tenants breaks down. The zooxanthellae begin to produce dangerous concentrations of oxygen radicals, and the polyps respond, desperately and often self-defeatingly, by expelling them. Without the zooxanthellae, which are the source of their fantastic colors, the corals appear to turn white—this is the phenomenon that’s become known as “coral bleaching.” Bleached colonies stop growing and, if the damage is severe enough, die. ([Location 2015](https://readwise.io/to_kindle?action=open&asin=B00EGJE4G2&location=2015)) - Everywhere on the surface of the earth temperatures fluctuate. They fluctuate from day to night and from season to season. Even in the tropics, where the difference between winter and summer is minimal, temperatures can vary significantly between the rainy and the dry seasons. Organisms have developed all sorts of ways of dealing with these variations. They hibernate or estivate or migrate. They dissipate heat through panting or conserve it by growing thicker coats of fur. Honeybees warm themselves by contracting the muscles in their thorax. Wood storks cool off by defecating on their own legs. (In very hot weather, wood storks may excrete on their legs as often as once a minute.) ([Location 2259](https://readwise.io/to_kindle?action=open&asin=B00EGJE4G2&location=2259)) - IN ecology, rules are hard to come by. One of the few that’s universally accepted is the “species-area relationship,” or SAR, which has been called the closest thing the discipline has to a periodic table. In its broadest formulation, the species-area relationship seems so simple as to be almost self-evident. The larger the area you sample, the greater the number of species you will encounter. ([Location 2341](https://readwise.io/to_kindle?action=open&asin=B00EGJE4G2&location=2341)) - recent estimates suggest there are at least two million tropical insect species and perhaps as many as seven million. By comparison, there are only about ten thousand species of birds in the entire world and only fifty-five hundred species of mammals. Thus for every species with hair and mammary glands, there are, in the tropics alone, at least three hundred with antennae and compound eyes. ([Location 2643](https://readwise.io/to_kindle?action=open&asin=B00EGJE4G2&location=2643)) - One of the defining features of the Anthropocene is that the world is changing in ways that compel species to move, and another is that it’s changing in ways that create barriers—roads, clear-cuts, cities—that prevent them from doing so. ([Location 2704](https://readwise.io/to_kindle?action=open&asin=B00EGJE4G2&location=2704)) - (Plantains—Plantago major—seem to have arrived with the very first white settlers and were such a reliable sign of their presence that the Native Americans referred to them as “white men’s footsteps. ([Location 2931](https://readwise.io/to_kindle?action=open&asin=B00EGJE4G2&location=2931)) - From the standpoint of the world’s biota, global travel represents a radically new phenomenon and, at the same time, a replay of the very old. The drifting apart of the continents that Wegener deduced from the fossil record is now being reversed—another way in which humans are running geologic history backward and at high speed. Think of it as a souped-up version of plate tectonics, minus the plates. By transporting Asian species to North America, and North American species to Australia, and Australian species to Africa, and European species to Antarctica, we are, in effect, reassembling the world into one enormous supercontinent—what biologists sometimes refer to as the New Pangaea. ([Location 2957](https://readwise.io/to_kindle?action=open&asin=B00EGJE4G2&location=2957)) - The megafauna extinction, it’s now clear, did not take place all at once, as Lyell and Wallace believed it had. Rather, it occurred in pulses. The first pulse, about forty thousand years ago, took out Australia’s giants. A second pulse hit North America and South America some twenty-five thousand years later. Madagascar’s giant lemurs, pygmy hippos, and elephant birds survived all the way into the Middle Ages. New Zealand’s moas made it as far as the Renaissance. It’s hard to see how such a sequence could be squared with a single climate change event. The sequence of the pulses and the sequence of human settlement, meanwhile, line up almost exactly. Archaeological evidence shows that people arrived first in Australia, about fifty thousand years ago. Only much later did they reach the Americas, and only many thousands of years after that did they make it to Madagascar and New Zealand. ([Location 3278](https://readwise.io/to_kindle?action=open&asin=B00EGJE4G2&location=3278)) - all non-Africans, from the New Guineans to the French to the Han Chinese, carry somewhere between one and four percent Neanderthal DNA. ([Location 3508](https://readwise.io/to_kindle?action=open&asin=B00EGJE4G2&location=3508)) - Archaic humans like Homo erectus “spread like many other mammals in the Old World,” Pääbo told me. “They never came to Madagascar, never to Australia. Neither did Neanderthals. It’s only fully modern humans who start this thing of venturing out on the ocean where you don’t see land. Part of that is technology, of course; you have to have ships to do it. But there is also, I like to think or say, some madness there. You know? How many people must have sailed out and vanished on the Pacific before you found Easter Island? I mean, it’s ridiculous. And why do you do that? Is it for the glory? For immortality? For curiosity? And now we go to Mars. We never stop. ([Location 3571](https://readwise.io/to_kindle?action=open&asin=B00EGJE4G2&location=3571)) - The Frozen Zoo maintains the world’s largest collection of species on ice, but an increasing number of other institutions are also assembling chilled menageries; the Cincinnati Zoo, for example, runs what it calls the CryoBioBank and England’s University of Nottingham operates the Frozen Ark. ([Location 3702](https://readwise.io/to_kindle?action=open&asin=B00EGJE4G2&location=3702)) - When a mass extinction occurs, it takes out the weak and also lays low the strong. V-shaped graptolites were everywhere, and then they were nowhere. Ammonites swam around for hundreds of millions of years, and then they were gone. The anthropologist Richard Leakey has warned that “Homo sapiens might not only be the agent of the sixth extinction, but also risks being one of its victims. ([Location 3807](https://readwise.io/to_kindle?action=open&asin=B00EGJE4G2&location=3807))