Problem: Warm-bloodedness means the testicles are now too warm to work well.
Hack #1: Hang them on the outside of the body so they can stay cooler.
New problem resulting from first hack: Now they're much easier to damage.
Hack #2: Make them hurt really bad if they get bashed, so the owner takes great care to guard them.
The proper solution would have to make them more temperature-tolerant in the first place.
Interestingly, ovaries didn't go down this road, though there are certainly some suboptimal designs in that whole system as well.
A fixed quantity of viable eggs within prime child bearing years until menopause when women would then perform other roles within the community.
Problem: Warm-bloodedness means the testicles are now too warm to work well.
Hack #1: Hang them on the outside of the body so they can stay cooler.
New problem resulting from first hack: Now they're much easier to damage.
Hack #2: Make them hurt really bad if they get bashed, so the owner takes great care to guard them.
The proper solution would have to make them more temperature-tolerant in the first place.
Interestingly, ovaries didn't go down this road, though there are certainly some suboptimal designs in that whole system as well.