Eat smarter. Exercise. Let the neighbors help raise your kids. Talk; talk a lot. Let seniors take part. Learn another language. Invest the way a farmer plants.

These are some of the wisdoms offered in Jared Diamond's new book, The World Until Yesterday: What Can We Learn From Traditional Societies? It joins a series of general-audience readings of history and society - including the Pulitzer Prize-winning Guns, Germs, and Steel of 1997, and Collapse of 2005 - in which Diamond, a professor of geography at UCLA, rethinks what it means to be human.

Is The World Until Yesterday yet another romance with the precivilized world? A few reviewers have suggested so. Wade Davis writes in the Guardian that "traditional societies do not exist to help us tweak our lives as we emulate a few of their cultural practices." Bryan Appleyard grumbles that "cruising round the premodern supermarket tossing habits of which we approve into our trolley is hardly scientific."

Speaking by phone from his hotel in Manhattan, Diamond agrees it's foolish to idealize the premodern world. "I'm quite clear in my book," he says, "that there are things about nonindustrial societies about which we should say, 'Thank God, they're past.' "

We don't, for example, strangle widows. We don't fight starvation and die at 44. "But we can learn from these societies," Diamond says, "about bringing up children, not forcing our seniors to retire, regulating our diets more wisely."

In World, Diamond, who will be at the Free Library Sunday, tells of many nonindustrialized societies, including several he has visited repeatedly over the years. His eye ranges wide - hunter-gatherers in New Guinea; neighbors who visit their institutionalized elders weekly, monthly, or seldom; Wayne Gretzky and his daughter Sara; the notorious 405 Freeway in Southern California; the last 11,000 years of human history. He builds up arguments about what works better and what not so well, what helps societies survive and what hinders.

It's a book that challenges the reader, once done reading, to change something, to get up and do.

"Throw away the salt shaker and sugar bowl in your house," he says, speaking of "changes that don't involve huge effort, things you can do yourself." Buy fresh fruits and veggies this afternoon. "And if you have a baby, throw away the baby carriage, in which the baby lies horizontally, looking backward at you, and buy a baby sling and carry the baby looking forward." That's a practice of many other cultures; some studies say it fosters greater peripheral and social awareness in infants.

"Some changes you'll have to talk to the neighbors about," Diamond says. "If you take the TV and video games away from your child, he or she will just go next door and watch them, unless you and your neighbor, and perhaps your whole block, cooperate." Alloparenting, in which other adults are involved in raising your child, is fast fading here - but Diamond sees plenty of advantages in the practice, widespread among hunter-gatherers.

And "some changes can happen only at the state level; they'll take more time and be more expensive." But look, he says, at what Finland, China, and other nations have done with dietary guidelines.

We need to change our diets to address diabetes and heart disease, which dog Western people later in life. (It's not all diet. Italians are slimmer, studies suggest, because they eat slowly and linger for long talks after meals.)

Other changes are less intuitive. Harvard University might not have lost so much of its endowment during the mid-2000s economic downturn, Diamond suggests, had investors followed strategies more like those of peasant farmers. Who knew?

People from many tribal societies learn multiple languages, leading to benefits less seen in folks from the notoriously monolingual United States. So Diamond is all for language learning in school. Bilingual babies show greater social awareness and flexibility. And "some studies suggest that learning one other language may hold off the onset of Alzheimer's five years," he says. "I wonder how much benefit three, or five, or 13 languages would give me."

The treatment of seniors is a "disaster area" of modern life, he writes. Mandated retirement-age policies, less common in the United States than they once were, are still widespread in Europe, something Diamond, 75, calls "stupid." Many seniors, from Diamond's own father (who practiced medicine into his 90s) to composers Richard Strauss and Giuseppe Verdi, contributed long into old age - a truth nonindustrial societies often take for granted.

Folks who aren't Diamond fans will point to his twisty-turny intellectual journey. He got his Ph.D. in gallbladder physiology at Cambridge in 1961. "But then I realized the world expected me to publish papers on the gallbladder for the rest of my life," he says with a chuckle. "I loved studying the gallbladder, but there were other things I wanted to do." He studied birds, the ecology, and environmental science. And when Diamond and his wife, Marie, became parents to twin sons in 1987, "I realized I wanted to do something to work on the future of the world, for my kids."

As his kids have grown, he adds, his personal choices have gotten better: "I do my push-ups every day, and I'll go to the gym with my sons. I can't do half the repetitions they can, but I'm getting my exercise."

Some non-fans get irritated by his general-audience approach, striding across disciplinary lines. But that has gotten him many fans, including Marilyn Silberfein, emeritus professor of geography and urban studies at Temple University. "More academics should write, as he does, for the larger public," she says. "It's edifying and stimulating to write across broad areas. At least it gets people thinking in new ways, about things they didn't know about before."

The World Until Yesterday reveals an essential optimism, a faith in people's power to learn from others (whether those others live in Peru or among the aborigines of Australia). "We ourselves are the only ones who created our new lifestyles," Diamond writes, "so it's completely in our power to change them."

That optimism, too, is something Diamond has developed: "When I've had terrible problems, usually either there's a way to address them or I'll find a way to survive them."

Finding ways to survive - to get to tomorrow - is what The World Until Yesterday is about.