Girls and boys reach puberty at different ages. Studies show that puberty in girls now starts at an earlier age. Although girls start earlier, boys' development continues after girls have reached full sexual maturity. Boys may be starting puberty earlier, too; however, there is no conclusive evidence for that yet. Boys usually start puberty about a year after girls, and their growth process is longer.
When children start puberty at an unusually early age, it is called precocious puberty. In the Western world, there are enough instances of this happening to make it a disturbing trend that indicates puberty is starting early for children, especially for girls. Precocious puberty in boys would be signs of puberty occurring before the age of nine. Some signs of precocious puberty are development of facial, pubic or underarm hair and a rapid growth spurt. Precocious puberty can cause emotional and social difficulties for boys; they can become more aggressive or display early signs of a sex drive that is not appropriate for their age.
There are some theories as to why this is happening, but the results of new research have yet to show whether this is a trend for children in general and why it's occurring. It may prove to be the result of environmental, nutritional or other factors. The obesity epidemic that is affecting children might be one of the triggers, but there are still not enough concrete facts. Precocious puberty is not common in boys, but sometimes it's hereditary. Boys that show signs of early puberty should be examined by a doctor to rule out possible health problems.