There's very little about being in a functional-M.R.I. scanner that is natural: you are flat on your back, absolutely still, with your head immobilized by pillows and straps. The scanner makes a dreadful din, which headphones barely muffle.

Beliefs about how lying looks are plentiful and often contradictory: depending on whom you choose to believe, liars can be detected because they fidget a lot, hold very still, cross their legs, cross their arms, look up, look down, make eye contact or fail to make eye contact.

If you're satisfied with your social life, according to psychologists, you tend to be satisfied with life in general.

Biology sets the context, and that is critical, but obesity still boils down to whether a person eats too much or exercises enough.

To me, it's always interesting to see what people end up regretting, as a way maybe to avoid such regrets in your own life.

In the womb, humans are free of microbes. Colonization begins during the journey down the birth canal, which is riddled with bacteria, some of which make their way onto the newborn's skin.