Why do genitalia serve this dual purpose? Is there some payoff or benefit for these organs to provide both functions of waste elimination and sexual reproduction?
Why not?Surely it's not just coincidental.
Fewer infections, hence lower mortality rate, hence better rate of survival, genes passed on...Hey-Presto, a genitila with two functions. :surprisedWhy not?
Unlike lower invertebrates, we have separation of ingestive and excretory openings. It also makes sense to have the fewest openings from the outside to the inside (the digestive tract really provides a closed tube through the body) so that the potential for infection penetrating the body cavity is reduced.