More and more NFL players have been willing their bodies to science so that their brains can be studied even if they die of other causes.

Members of royal families are born into a world of indulgence and entitlement, and the princelings who grow up that way may never have to develop the emotional musculature that will allow them to show self-restraint.

More and more NFL players have been willing their bodies to science so that their brains can be studied even if they die of other causes.

When we're awake, cortisol can fragment memories - one reason eyewitness crime scene accounts are so unreliable. But at night that very fragmentation allows creative recombinations of ideas.

Older 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.

Older fatherhood isn't all bad: testosterone rates drop about 1% per year as men age, making them less reactive and more patient, and a professionally established middle-aged man is likely to have more time and money to devote to his kids than a twenty-something who's just getting started.

The vexing thing about human behavior is that when we say we know we should do something, we really and truly do know it. It's hard to be 50 lbs. overweight or smoke a pack a day or feel miserable every moment you spend at work and not understand in a deep and primal way that change is in order - and that in some cases it could even save your life.