There's No Such Thing As Downtime For

When 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.

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.

Every 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.

A Jellyfish Is Little More Than A Pulsating Bell, A Tassel Of Trailing Tentacles And A Single Digestive Opening Through Which It Both Eats And Excretes - As Regrettable An Example Of Economy Of Design As Ever Was.

Ambition Is An Expensive Impulse, One That Requires An Enormous Investment Of Emotional Capital. Like Any Investment, It Can Pay Off In Countless Different Kinds Of Coin.