Fascinating simulation shows what happens to ‘dead’ sperm after sex

Joe Harker
2026-03-18T15:25:03.200Z
News

It only takes one to reach the egg, the rest of them will die

In your life if you want to cling to any one comforting thought it's that you were the winning sperm.

Everyone in the world starts life as a winner, defeating a huge number of potential siblings in a race to be the one that made it to the egg that would ultimately grow into the person that is you.

But if you ever wondered what happened to all of the other sperm that didn't make it to the egg then the answer is quite simple, they died.

Sorry gang, your victory in the race to the egg went a bit The Long Walk and there can only be one left alive by the end as there's no space for second place in the human reproductive system.

During ejaculation millions of sperm are released and only one makes it while sex is going on and they swim through the reproductive tract.

The sperm is guided by chemicals released by the egg and there's all sorts of different speeds they travel at with some taking mere minutes to make it while others would require days.

While one lucky swimmer might make it and fertilise the egg the rest of them are unlucky losers, they can survive in the female reproductive tract for up to five days but after that they are going to be dead.

The cervical mucus is a reasonable sperm-friendly environment to give the failed swimmers somewhere to exist in for a few days before dying.

The human immune system will recognise the sperm as a foreign cell and break it down until there's nothing left, while any remaining leftover bits are naturally recycled and sometimes disposed of as part of discharge.

A human body is a very sophisticated thing which knows how to get rid of a lot of things it doesn't need, as the reproductive system doesn't need the millions of other sperm once one lucky swimmer has managed to make it to the egg.

Dead sperm cells are eventually broken down and flushed out (Getty Stock Photo)

It can certainly survive longer there than outside the body, as they can live up to an hour outside the body at room temperature which is not very long at all.

The longest they can survive is back home in a bloke's testicles, as long as we're not counting frozen samples of sperm which can last for decades in a preserved state.

Barring the frozen samples, sperm will last longest in the testicles as they live there for around two-and-a-half months before it's time for them to get busy swimming or get busy dying.

When sperm dies inside a man's body it gets broken down and recycled to build new cells, including new sperm cells.