Hank: Let's have a talk about sperm. Whether or not you're keen on becoming a parent anytime soon, it's useful to know how long those sperm could survive in the female reproductive system. And that might be a lot longer than you'd think.

Now, sperm will dry out within minutes of exposure to air, but they remain viable for days nestled in the walls of the cervix, in little striations called "crypts," waiting for the chance to fertilize an egg.

The cervix actually chemically alters sperm through a process called "post-ejaculatory modifications to sperm," or PEMS. And these modifications help sperm survive crypt storage, navigate the female reproductive tract, and even give it the ability to fertilize the egg.

And human sperm need between three and 24 hours in the PEMS process to be viable at all. With the help of its host, sperm can retain their ability to fertilize an egg for 48 hours after ejaculation.

Do with this information what you will.

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