Data bandwidth of sex

When you strip away everything, sex is really about moving information from one body to another. In fact, data connectors for computers were originally named after sexual roles. The genders have gotten a bit ambiguous recently, but you can still call the USB port on the bottom of your phone “female”, and the thing that plugs into it “male”.

How much information? We need to be careful here. According to Landauer’s Principle, every bit releases some amount of heat. If we move bits too fast, the connector might melt, which would be unfortunate.

So to talk about bit rate, we first need to decide how long the information transfer takes. If you include all the surrounding rituals, that could be hours, days, even years. Intercourse itself could last an hour or more. But to be most precise, the actual data transfer lasts about ten seconds.

The average human emission contains 250 million sperm. Each sperm carries a nearly full copy of the human genome, about 300 million base pairs. Each base pair is worth 2 bits. Total data is roughly 19 petabytes. That’s twice the bandwidth of the entire global Internet for ten seconds! Whew, the connector is melting …

But actually this is wrong. According to Shannon, something only counts as information if it is not predictable by the recipient. The female already has a full copy of the human genome, so only the differences count. Any two people have about 12 million base pairs different. That’s 3 megabytes. Not so bad. The connector is nice and cool …

But actually we need to count one more thing. During crossover, the male selects which of his two sets of genes gets used for each section of DNA. Let’s say there are 2 crossover sites per chromosome, or about 50 total. The key information here is where the crossover occurs. A chromosome has on average 13 million base pairs. To encode one location requires about 24 bits (3 bytes). Each sperm carries 150 bytes of crossover info (one text message worth). Times the number of sperm, that’s 38 gigabytes. Now we’re just passing a thumb-drive.

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