Many animals have an actual free floating bone in the end of the penis called a baculum. One theorized reason for this is that the baculum allows for the penis to enter a vagina without lubrication much like a shoehorn.
Another reason is that the baculum allows for prolonged sexual encounters. Humans are thought to have evolved without an actual bone since we have less sexual partners (not true for everyone though!!), shorter intercourse duration of around 2 minutes (also not true for everyone!!).
Either way, maybe it's better we don’t have a penis bone. It would be an extra thing to break!!!
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