The Importance of Touch on Infants

Touch plays a very special role in the life of young babies. Because it is so well developed at birth, it provides these brand-new arrivals more detailed access to their fascinating new world than any other sense. Touch is obviously essential to babies' sensory-motor development, but it also has a surprisingly potent influence over their physical growth, emotional well-being, cognitive potential, and even their overall health, because of some fascinating effects on their immune function. [....

 The Waist-to-Hip Ratio

Why does the waist-to-hip ratio matter? Singh observes that a "gynoid" fat distribution—more fat on the hips, less on the torso—is necessary for the hormonal changes associated with female fertility. An "android" fat distribution-—fat on the belly, thin hips—is associated with the symptoms of male disabilities such as heart disease, even in women. But which is cause and which effect? It seems to me more likely that both the shape and the hormonal effects of it are sexually selected by...

 How Testosterone Affects the Brain

We last met the steroid hormone testosterone in fish and birds where it was rendering them more vulnerable to parasites by exaggerating their sexual ornaments. In recent years more and more evidence has been found that testosterone affects not just ornaments and bodies but also brains. Testosterone is an ancient chemical. found in much the same form throughout the vertebrates. Its concentration determines aggressiveness so exactly that in birds with reversed sex roles, such as phalaropes and ...