LIVE SCIENCE: Man should shed at least one billion of sparm per month.

the average male will produce roughly 525 billion sperm cells over a lifetime and shed at least one billion of them per month. A healthy adult male can release between 40 million and 1.2 billion sperm cells in a single ejaculation.

In contrast, women are born with an average 2 million egg follicles, the reproductive structures that give rise to eggs. By puberty, a majority of those follicles close up and only about 450 will ever release mature eggs for fertilization.

But if it only takes one sperm and one egg to meet and create a baby, then why do men produce such a whopping number of sperm? Wouldn't it be less wasteful for a man to release a single sperm, or at least fewer, to meet one egg?

This kind of competition is an evolutionary imperative for males of any species. If a rival's sperm fertilizes an egg, then an opportunity to pass on your genes is lost. Through many generations, as the reproductive spoils continually go to the highest sperm producers, their genes are passed on. The genes of the smaller sperm producers are eventually weeded out of the population and become a footnote to evolutionary history.

But if it was just a matter of "more is better," then animals of all species would have evolved ridiculously large testicles in a bid to overwhelm the competition. But it’s not quite that simple — numbers are important, but so is proximity. Fertilizing an egg is not just about how much sperm you can produce. It is also about how close you get your sperm to it.

In the early 1980s, researchers in the United Kingdom and the United States realized that both proximity and number were important factors in the physiology of primates, including humans. In primate societies with rigid social structures and one dominant male who mates with all the females, testes trend towards the small. In gorillas, for example, they are very small relative to body weight. (Don’t tell them that.) In gorilla society, one male defends a harem of females to ensure only his sperm gets anywhere near their eggs. In this case, making a lot of sperm doesn’t really help the male gorilla get the job done.