Animals on the verge What different species can teach us about human puberty

We all go through it: The often-awkward years of adolescence, marked by puberty. This transition period has a dramatic effect, yet surprisingly little attention has been given to studying it. Researchers have even struggled to come up with a universal definition of puberty. Still, most agree that puberty is the process involving a cascade of hormonal events that allows a juvenile organism to become sexually mature. And, even though entering puberty alone might be sufficient for animals to reproduce, many organisms-humans included-tend to reproduce after this transition phase. Female macaques, for instance, can have babies when they are as young as three years old, but there's a higher rate of infant mortality at this age and they typically mate a little later. Among humans, teen moms have a higher risk of complications for themselves and their babies than those who give birth in their prime reproductive years. Puberty, by being a drawn-out process in many creatures, might help ease animals into reproductive maturity to ensure better survival of offspring, some scientists believe. What still confounds researchers in large part is what initially triggers puberty. Those who study the biochemical properties of puberty wonder whether environmental factors, an internal clock of some kind, or a combination of these determines when humans enter puberty. The answers to many such questions are being investigated in laboratory organisms, such as rodents. But unexpected insights are also coming from the study of an exotic mix across the animal kingdom. Puberty is amazing in that it literally affects pretty much every species, and so there's a lot to be learned from all that diversity, says Melissa Holmes, a behavioral neuroscientist at the University of Toronto in Mississauga, Canada. We know that most all animals go through this, so the devil is really in the details.