A special report by LiveScience: Toward Immortality

For about 50 years, caloric restriction (CR) was the only proven method to extend an organism's maximum life span in a healthy way.

Then in 1996, scientists discovered a type of mutant dwarf mouse that lived up to 70 percent longer than its non-mutated peers. The rodents' stunted growth was due to a change at the genetic level that reduced production of hormones related to growth.

Using mice, the researchers found that mothers fed protein-rich diets during pregnancy, but low-protein diets while breast-feeding, had pups that lived up to 50 percent longer than those for whom this feeding pattern was reversed. If a similar approach could work for humans, this translates into a difference between reaching 50 and living to be 75 years old, the researchers said.

Important for Susan Greenfield, a professor of pharmacology at Oxford University, her theory is a distinction between 'consciousness' and 'mind,' terms that she says many of her colleagues use interchangeably, but which she believes are two entirely different concepts.

"You talk about losing your mind or blowing your mind or being out of your mind, but those things don't necessarily entail a loss of consciousness," Greenfield said in a telephone interview. "Similarly, when you lose your consciousness, when you go to sleep at night or when you're anesthetized, you don't really think that you're really going to be losing your mind."

But whereas the mind is rooted in the physical connections between neurons, Greenfield believes that consciousness is an emergent property of the brain, similar to the 'wetness' of water or the 'transparency' of glass, both of which are properties that are the result of -- that is, they emerge from -- the actions of individual molecules.

For Greenfield, a conscious experience occurs when a stimulus -- either external, like a sensation, or internal, like a thought or a memory -- triggers a chain reaction within the brain. Like in an earthquake, each conscious experience has an epicenter, and ripples from that epicenter travels across the brain, recruiting neurons as they go.

Happiness is 50 percent genetic, says University of Minnesota researcher David Lykken. What you do with the other half of the challenge depends largely on determination, psychologists agree. As Abraham Lincoln once said, "Most people are as happy as they make up their minds to be."

One route to more happiness is called "flow," an engrossing state that comes during creative or playful activity, psychologist Mihaly Csikszentmihalyi has found. Athletes, musicians, writers, gamers, and religious adherents know the feeling. It comes less from what you're doing than from how you do it.

Make lists of things for which you're grateful in your life, practice random acts of kindness, forgive your enemies, notice life's small pleasures, take care of your health, practice positive thinking, and invest time and energy into friendships and family.

"Research shows that people who are grateful, optimistic and forgiving have better experiences with their lives, more happiness, fewer strokes, and higher incomes," according to Gregg Easterbrook, author of "The Progress Paradox: How Life Gets Better While People Feel Worse" (Random House, 2004). "If it makes world a better place at same time, this is a real bonus."