Consider the following set of figures: 148.4 150 150-200 125 Those numbers represent the population averages of hunter-gatherer tribes, Stone Age groups, villages in ancient Mesopotamia, and ancient Roman military legions.

This reality is already here. The Japanese government reports that there are half a million young Japanese who refuse to leave their bedrooms. They are called hikikomori, basically people who have sent themselves into an extended time-out.

Today it’s possible to move into a big-city apartment and decide never to leave it. Literally never to walk back through the front door for years. It requires only a decent Internet connection to perform a job remotely, order food and groceries for delivery, and connect with telemedicine.

The world had the Desert Fathers and Mothers, monks who in the third century left civilization to live alone in the Egyptian desert.

At the signing of the Declaration of Independence only 5 percent of us were urbanites. By 1876, that number was still just 25 percent. But roughly 100 years ago we tipped to favor city living. Today, 84 percent of Americans live in cities and more are moving in. It’s an odd trend.

“AS OUR AIRPLANES get smaller, our adventure gets bigger,” Donnie told me as we planned for the trip.

Additionally, stepping outside our comfort zone to learn useful skills that require both mind and body alters our brain’s wiring on a deep level. This can increase our productivity and resilience against some diseases. Learning improves myelination, a process that essentially gives our nervous system a V-8 engine, creating stronger, more efficient

A team of scientists in Israel confirmed James’s notion in a series of six studies. They surveyed groups of people doing things that were either new or old to them. “In all studies,” the scientists wrote, “we found that…people remember duration as being shorter on a routine activity than on a nonroutine activity.”

Scientists in the United Kingdom recently found that our brain has a trancelike “autopilot” or “sleepwalking” mode. Once we’ve done something over and over, our mind zones out of whatever old thing it’s doing. Instead of being present and aware, we’re far more likely to be lost somewhere inside our noggin. We’re planning what we’ll eat for dinner,