EVANSTON, Ill., Sept. 13 (UPI) — Males who experience rapid weight gain in the first six months of life reach puberty sooner and are taller and more muscular, a study suggests.
A Northwestern University study of men in the Philippines found adult males who had rapid growth as babies — indicating they were not nutritionally stressed — grow up stronger and show higher testosterone levels as young adults, a university release said Monday.
Testosterone may hold the key to understanding these long-term effects, researchers say.
“Most people are unaware that male infants in the first six months of life produce testosterone at approximately the same level as an adult male,” Christopher W. Kuzawa, associate professor of anthropology and author of the study, said. “We looked at weight gain during this particular window of early life development, because testosterone is very high at this age and helps shape the differences between males and females.”
The study is evidence that genes alone do not predict our adult fate, researchers say.
“The environment has a very strong hand in how we turn out,” Kuzawa said. “And this study extends that idea to the realm of sex differences and male biology.”
The magnitude of difference in height and strength between men and women appears to be the result of nutrition within the first six months of an infant male’s life, the study determined.
“Another way to look at it is that the differences between the sexes are not hard wired, but are responsive to the environment, and in particular to nutrition,” Kuzawa said.
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