The sperm motility, which means how well sperm can swim, was highest in June and July, while the lowest levels were recorded in December and January.

Small RNA molecules in the blood can predict two-year survival in older adults more accurately than age or other common health measures.

Humans don’t have a defined mating season like deer or wolves. Here’s how evolution blended biology, culture and social life into year-round intimacy.

Scientists have uncovered a surprising new way that giant embryonic cells divide—without relying on the classic “purse-string” ring long thought essential for splitting a cell in two. Studying ...