Whether it is sprouting hair, budding breasts or a breaking voice, the signs that herald puberty can be distressing and difficult to cope with.
In the western world there is much evidence children are reaching puberty at younger and younger ages - some girls at the age of seven.
The reasons for this trend is unknown - and some dispute it is occuring at all.
But several theories have been suggested.
And Swedish scientists at the Karolinska Institute aim to find out by tackling the puzzle from different angles.
The rest in: http://news.bbc.co.uk/2/hi/health/4530743.stm
IMO the reason behind this is the huge dosis of hormones that animals receive so they can develop faster.