Paul McCartney had a baby when he was 61; Rod Stewart was 66; Rupert Murdoch was a stunning 72. Not only does that mean they'll have less stamina than the average dad, that means they'll, well, check out a lot sooner too.

The brain sits snugly inside the skull, but it's not a completely flush fit - there is still a layer of fluid between bone and soft tissue that serves as a natural shock absorber. Some shocks, however, can't be absorbed, and when the head gets clobbered too hard, the brain can twist or torque or rattle around inside its skeletal casing.

There's only one thing harder than living in a home with an adolescent - and that's being an adolescent. The moodiness, the volatility, the wholesale lack of impulse control, all would be close to clinical conditions if they occurred at another point in life. In adolescence, they're just part of the behavioral portfolio.

Vaccines save lives; fear endangers them. It's a simple message parents need to keep hearing.

Toxins love to get you while you're young. Lead, mercury, secondhand smoke and sundry other environmental nasties do a lot more damage when tissue is immature, vulnerable and growing than when it's mature and comparatively fixed.

A cockroach likely has no less brainpower than a butterfly, but we're quicker to deny it consciousness because it's a species we dislike.

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.