At what point in history did humanity achieve continuous sex?

Factual Questions
1

The question Pee! wanted to ask his class*, but couldn’t!

Obviously, with almost 7 billion people on Earth, there is never a time when a person is not having sex. What I wanted to figure out is when it started.

[See Pee!'s thread for the rest of the text, making changes as appropriate.]
I’m certain this occurred after the continuous stream of urine, but when? Does it matter much if only straight intercourse counts? (Let’s specify that masturbation doesn’t count.)

  • OK, probably not.
2

Why? I’m sure that even with a much lower frequency, the time spent having sex is longer than the time spent urinating (e.g. 1 minute (total) per day of urinating vs. 30 minutes* of sex, just once), and early humans were no doubt much more promiscuous than today.

*Of course, the time should be halved to account for the need for two people instead of one (assume no orgies) , but it is still significantly greater.

3

What makes you think that?

4

Obligatory xkcd.