Men have nipples, mammary glands and the hormones required, but the ability for male lactation rarely turns on. Here’s why evolution mostly suppresses it.

Sperm and egg cells, or gametes, are unusual. Egg cells are some of the largest cell types, and sperm are some of the smallest. In humans, these haploid cells come together to form diploid cells. It's ...

Reproduction involves making quality gametes – egg and sperm – which are essential for species continuity and therefore have huge implications for human health. The quality of the gametes is not only ...