Of course, the researchers could simply be demonstrating the effects of nutrition on male development — or even the effects of breast - feeding. (scientificamerican.com)
For example, in humans, the Y chromosome triggers male development. (sciencedaily.com)
Rather, «male differentiation requires two copies of a Z - borne gene, the expression or activity of which is sufficient for male development only at optimal temperatures,» the researchers write in the current Science. (scientificamerican.com)