4. Things that taste good are bad for you.
In 1948, the Framingham Heart Study enrolled more than 5,000 residents of Framingham, Massachusetts, to participate in a long-term study of risk factors for heart disease. (Very long term—the study is now enrolling the grandchildren of the original volunteers.) It and subsequent ambitious and painstaking epidemiological studies have shown that one’s risk of heart disease, stroke, diabetes, certain kinds of cancer and other health problems increases in a dose-dependent manner upon exposure to delicious food. Steak, salty French fries, eggs Benedict, triple-fudge brownies with whipped cream—turns out they’re killers. Sure, some tasty things are healthy—blueberries, snow peas, nuts and maybe even (oh, please) red wine. But on balance, human taste preferences evolved during times of scarcity, when it made sense for our hunter-gatherer ancestors to gorge on as much salt and fat and sugar as possible. In the age of Hostess pies and sedentary lifestyles, those cravings aren’t so adaptive.
Einstein’s famous equation is certainly one of the most brilliant and beautiful scientific discoveries—but it’s also one of the most disturbing. The power explained by the equation really rests in the c², or the speed of light (186,282 miles per second) times itself, which equals 34,700,983,524. When that’s your multiplier, you don’t need much mass—a smidgen of plutonium is plenty—to create enough energy to destroy a city.
6. Your mind is not your own.
Freud might have been wrong in the details, but one of his main ideas—that a lot of our behaviors and beliefs and emotions are driven by factors we are unaware of—turns out to be correct. If you’re in a happy, optimistic, ambitious mood, check the weather. Sunny days make people happier and more helpful. In a taste test, you’re likely to have a strong preference for the first sample you taste—even if all of the samples are identical. The more often you see a person or an object, the more you’ll like it. Mating decisions are based partly on smell. Our cognitive failings are legion: we take a few anecdotes and make incorrect generalizations, we misinterpret information to support our preconceptions, and we’re easily distracted or swayed by irrelevant details. And what we think of as memories are merely stories we tell ourselves anew each time we recall an event. That’s true even for flashbulb memories, the ones that feel as though they’ve been burned into the brain:
Like millions of people, [neuroscientist Karim] Nader has vivid and emotional memories of the September 11, 2001, attacks and their aftermath. But as an expert on memory, and, in particular, on the malleability of memory, he knows better than to fully trust his recollections… As clear and detailed as these memories feel, psychologists find they are surprisingly inaccurate.
7. We’re all apes.
It’s kind of deflating, isn’t it? Darwin’s theory of evolution by natural selection can be inspiring: perhaps you’re awed by the vastness of geologic time or marvel at the variety of Earth’s creatures. The ability to appreciate and understand nature is just the sort of thing that is supposed to make us special, but instead it allowed us to realize that we’re merely a recent variation on the primate body plan. We may have a greater capacity for abstract thought than chimps do, but we’re weaker than gorillas, less agile in the treetops than orangutans and more ill-tempered than bonobos.
Charles Darwin started life as a creationist and only gradually came to realize the significance of the variation he observed in his travels aboard the Beagle. For the past 151 years, since On the Origin of Species was published, people have been arguing over evolution. Our ape ancestry conflicts with every culture’s creation myth and isn’t particularly intuitive, but everything we’ve learned since then—in biology, geology, genetics, paleontology, even chemistry and physics—supports his great insight.
8. Cultures throughout history and around the world have engaged in ritual human sacrifice.
Say you’re about to die and are packing some supplies for the afterlife. What to take? A couple of coins for the ferryman? Some flowers, maybe, or mementos of your loved ones? If you were an ancient Egyptian pharaoh, you’d have your servants slaughtered and buried adjacent to your tomb. Concubines were sacrificed in China to be eternal companions; certain Indian sects required human sacrifices. The Aztecs slaughtered tens of thousands of people to inaugurate the Great Pyramid of Tenochtitlan; after sacred Mayan ballgames, the losing team was sometimes sacrificed.