http://news.bbc.co.uk/hi/english/sci/tech/newsid_1694000/1694591.stm
By the BBC's Ania Lichtarowicz
Prehistoric humans did not go through a period of adolescence, according to
new scientific evidence published in the journal Nature.
Scientists believe that one of our ancestors, Homo erectus, may have
developed more like an ape and missed out on adolescence - which evolved in
later humans to allow for extra learning time.
Homo erectus roamed parts of Africa about two million years ago and showed
many modern human characteristics, such as shorter arms.
Scientists had believed these features all evolved simultaneously to create
modern man, but a new study on the fossilised teeth of Homo erectus shows he
was never a typical teenager.
Ape-like
Teeth are a very accurate way of calculating how old someone is, and how
quickly they develop shows how quickly an individual reaches adulthood.
Adolescence as we know it developed about half a million years ago,
scientists say
By cutting thin sections of a tooth and looking at it under a powerful
microscope, it was possible to count markings in the tooth enamel to
determine how long it had taken for the tooth to grow.
These markings are like tree rings, and very accurately measure the age of an
individual.
It appears that early human ancestors grew up very much like today's great
apes - taking about 12 years to reach adulthood.
Modern humans on the other hand take much longer - up to 20 years.
Small brain
The difference seems to allow us to learn how to use our bigger brains.
The research carried out on the fossilised teeth suggests that the extended
period of adolescence, as we know it, only developed about half a million
years ago.
The scientists behind the work say that if Homo erectus did not go through
adolescence, then he did not need an extended learning time.
This, they say, is because he still had a small ape-like brain.
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