A new study from Northwestern University draws a connection between gender differences and infant nutrition. According to data from a group of 770 Filipino men who have been studied their entire lives, male infants with big appetites who gained the most weight during their first six months developed faster over time. The hungry men not only grew up taller and stronger than their peers, they had higher testosterone levels and began having sex at a younger age.
The researchers think the nutrition link has something to do with testosterone, which male babies actually produce at roughly the same rate as adult males. Infant diet might determine how heavy a dose of the hormone guys get as they age. So what does that have to do with gender? Testosterone helps distinguish males from females since it's responsible for many physical gender differences -- such as muscle mass and height. The findings also score a point for the "nurture" aspect of gender, exemplifying how environmental forces can shape one's genetic makeup early in life. In this way, the study supports the concept of a gender spectrum, rather than set definitions of what constitutes males and females.
Although the study correlates infant weight gain with positive physical outcomes, babies putting on too many pounds can pose health problems. Today, the childhood obesity epidemic has trickled down to the crib, and infant obesity has become a hot topic in the pediatric community. For instance, a recent study of overweight boys found that a quarter of them were tipping the scales too far by just 5 months old. Rather than prepping them for reproductive success, those extra ounces and pounds portend high blood pressure and diabetes down the road.
The study also left me wondering how a hearty infant appetite affects girls. Surely, if it can have such a profound impact on male development, early childhood nutrition must environmentally shape girls' lives as well. Looks like I'll have to wait on Science to find out.