There are a lot of obstacles in the way of our understanding animal intelligence - not the least being that we can't even agree whether nonhuman species are conscious. We accept that chimps and dolphins experience awareness; we like to think dogs and cats do. But what about mice and newts? What about a fly? Is anything going on there at all?
Jeffrey KlugerOlder siblings get more total-immersion mentoring with their parents before younger siblings come along. As a result, they get an IQ and linguistic advantage because they are the exclusive focus of their parents' attention.
Jeffrey KlugerPsychopaths know the technical difference between right and wrong - which is one of the reasons their insanity pleas in criminal cases so rarely succeed; they just fail to act on that knowledge.
Jeffrey KlugerEvery batch of sperm represents an opportunity for genetic typos - called de novo mutations - to be passed on. A 20-year-old man and woman will each pass on about 20 de novo mutations to a baby they conceive. By the time the couple is 40, a woman's total has remained at 20, while a man's has jumped to 65 - and it keeps climbing from there.
Jeffrey KlugerWhen you're your parents' one shot at a genetic legacy, you may get to attend all the best schools, wear all the best clothes and eat all the best foods - at least relative to children in multiple-sibling households. But you also wind up with an overweening sense of your own importance.
Jeffrey Kluger