If we were a culture of high-risk alcoholics, and suddenly we had Jack Daniels piped into our houses, we would be feeding that fire. Social networking, and the internet as a whole, seems to have simply landed in an extremely fertile place in an extremely fertile time in history, when we all have these narcissistic tendencies anyway - you can go further back into the self-esteem movement, and Dr. Spock, and the 'everybody gets a ribbon at the track meet' sort of thing, which preceded the internet - and then you drop the internet into the middle of this, and we've all gone haywire.

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?

Tamerlan Tsarnaev is telling no tales. The older of the two brothers who committed the Boston Marathon bombings was likely the one who planned the attack, but when he died in a shootout with police just days after the blasts, his thoughts and motivations vanished with him.

The truth, of course, is that the only necessary and sufficient condition for human beings to murder one another is the simple fact of being human.

Spare a thought for the poor introverts among us. In a world of party animals and glad-handers, they're the ones who stand by the punch bowl. In a world of mixers and pub crawls, they prefer to stay home with a book. Everywhere around them, cell phones ring and e-mails chime and they just want a little quiet.

Kids whose puberty begins too soon face not just psychological risks, but physical ones too, with an increased likelihood of cancer, as well as skeletal changes that could prevent them from attaining their full adult height.

Indeed, the best way to think of willpower is not as some shapeless behavioral trait but as a sort of psychic muscle, one that can atrophy or grow stronger depending on how it's used.