It is a well-known fact that when the Class of Mammalian branched off the Phylum Chorda, they had tails and walked on all fours. Standing up to reach bananas, and expose their genitalia to potential mates, created a problem. As they got older, and the sphincter muscles laxed, they would accidentally shit on their tails in the upright position. Spending most of their lives standing erect and showing off their junk, the humanoid bunch knew their shit-stained tails had to go, so they evolved the skin right off of them. The trouble was: what to do with their flexible spinal cords that were now dangling in space. The answer was simple: just tuck the extra slack back up into the groin. And so, they did. The good news was that it was flexible and could bend around the anus because you did not want a cable full of nerves passing through the garbage compactor. From this point on, the different sexes created 2 paths. The females of the species, which are known as: front butts, because the butt crack comes all the way around and terminates in the front, had to avoid another external opening known as the veegee squeegee. It was easy to do because it was already diverted around the poop pipe. This spinal cord now terminated at knobby protrusion known as the clitoris at the very end of the front butt. It all worked out well for the female, as the open end of the main transmission line was well protected in a sheathed, labia lined trench. As for the males, they did not fair out so well because as soon as that nerve network got around the crap cavity, it was forced outside the body and terminated at a fleshy stalk known as the penis. Hanging out there with his 2 buddies that lived in a bag, the situation was totally nuts. Three amigos with more sensors than a spy satellite, were on their own: out in the great outdoors. Nature knew these guys were exposed to grave dangers, so just like the Wizard of Oz, she gave the flexible scarecrow (Dick) an amazing brain.