LogFAQs > #968239702

wackyteen posted...

isn't the penis just like an overgrown [redacted]? Making female the default gender? (I remember hearing/reading this in passing)

It's more efficient to reuse the same basic structures for more complex ones.
That's why guys have nipples.

You go through two sets of rudimentary kidneys before the final ones show up, and the first set never makes it to functional, mostly because it's easier to build a kidney out of the remnants of the second set that's built out of the remnants of the first set. Also that second set ends up being repurposed as the framework for the reproductive system.