It's not just girls: Boys are now hitting puberty a year earlier, finds study. Boys are on a faster track to puberty reaching the milestone an average year earlier than their fathers' generation, a study has found。

　　A study in Bulgaria found boys today start to develop at 12 years old, while those in the 1970s began changing when they were aged 13.

　　The findings suggest that trends towards earlier puberty aren't limited to girls, who have already been shown to be developing sexually at increasingly younger ages。

　　Researchers from Cedars Sinai Medical Center in Los Angeles compared 6,200 healthy boys with a similar 1970s study。

　　In the study, reported in the Archives of Pediatrics and Adolescent Medicine, they measured height, weight, testicular volume, penis length and circumference。

　　Study leader Dr Fnu Deepinder: 'Studies done several decades ago in the same population reported that a leap forward in sexual development occurs at ages 13 through 16.''However, our study indicated that this spurt takes place between 12 and 15 years old.'

　　有研究表明，青春期提前已不在是女孩子的“专利”了，之前有调查显示，男孩的性成熟年龄已经越发提前。来自洛杉矶的科学家们测量了 6200例健康男孩的身体数据，其中包括身高、体重、睾丸体积、阴茎长度与周长，再将之与上世纪七十年代的数值进行了比较，结果表明，男孩在13到16周岁间性发育已经成熟，提前了很多，据研究的负责表示，现在的性成熟年龄已经提前到了12到15周岁之间。

　　The team found that boys' testicles did not grow substantially until the beginning of puberty, around age 11. However, penises appeared to grow gradually from birth to sexual maturity, starting at around 2 inches and reaching an average length of nearly 4 inches by the age of 19.

　　该研究小组发现，男孩们的睾丸自十一岁起开始快速发育，阴茎长度也日趋成熟，从出生时的两英寸发育到了十九岁时平均四英寸的程度。

　　However, both penises and testicles grew most rapidly between ages 12 to 16, while boys added the most inches in height and gained the most weight between 12 and 14 years old。

　　尽管如此，阴茎与睾丸的发育高峰期出现在12到16岁间，而另一方面，男孩们长个子与体重的增加黄金时期则是12到14岁之间。

　　The study fund that boys of the same age in the 1970s study had relatively smaller genitalia. However, these size differences disappeared between the two generations by the age of 17.

　　研究中还发现，与如今同年龄段的男孩比较，上世纪七十年代的男孩生殖器相对较小，但两代人的这一差异在17岁时便消失了。

　　Dr Deepinder said that genetic, environmental, nutritional and educational factors could all be behind the faster development today, but it remains unclear what impact earlier puberty might have on men's health。

　　负责人表示，遗传、环境、营养以及教育等方面的变化都是促成发育提前的因素，但对于性早熟为否对男性健康造成影响，目前还不得而知。