Conventionally, steroid hormones are understood to act within individuals, originating from the gonads and adrenals and affecting targets including the uterus and brain. Estrogens are the smallest and most powerful steroids, acting within females to control sexual maturation and fertility. This lab has found that estrogens can also pass between individuals. In lab mice, they are excreted by males and then enter females' bodies where they bind in the uterus and brain and alter the females' reproductive state. We have also found abundant quantities of estrogens and androgens in men's perspiration, suggesting possible pheromonal action in people.

Denys deCatanzaro is Professor of Psychology, Neuroscience & Behaviour at McMaster University. He has extensively researched the roles of androgens and estrogens in early pregnancy and puberty, including the influences of man-made chemicals that mimic these natural steroids. He has published two books and over 80 scientific articles.

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