India, April 19 -- These were prodigies, certainly. But given how low life expectancy was until the modern era, researchers now believe that a large share of humanity's most dramatic discoveries-harnessing fire, the wheel, smelting, and plenty more - were likely made by people who were quite young. Necessity drove invention, and necessity meant there were few rules about the burdens young people could carry. The rules society has evolved are, of course, vital. But new studies indicate that, amid current societal structures, the threshold of adulthood may be moving further up. We are now at the point where humans may not be maturing into full adulthood until the age of. 32. A study by neuroscientists at Cambridge University suggests that mos...