New research from around the world has begun to reveal a picture of humans today that is so different from what it was in the past that scientists say they are startled. Over the past 100 years, says one researcher ... humans in the industrialized world have undergone a form of evolution that is unique not only to humankind, but unique among the 7,000 or so generations of humans who have ever inhabited the earth." The difference does not involve changes in genes, as far as is known, but changes in the human form. Many chronic ailments like heart disease, lung disease and arthritis are occurring an average of 10 to 25 years later than they used to. There is also less disability among older people today. Human bodies are simply not breaking down the way they did before. Even the human mind seems improved. The average I.Q. has been increasing for decades, and at least one study found that a person's chances of having dementia in old age appeared to have fallen in recent years. Improved medical care is only part of the explanation; studies suggest that the effects seem to have been set in motion by events early in life, even in the womb, that show up in middle and old age. Of course, there were people in previous generations who lived long and healthy lives, and there are people today whose lives are cut short by disease or who suffer for years with chronic ailments. But on average, the changes, researchers say, are huge.