Biblical study and biology combine in this treatise:
“Congenital human baculum deficiency: The generative bone of Genesis,” Scott F. Gilbert [pictured here] and Ziony Zevit, American Journal of Medical Genetics, vol. 101, no. 3, 2001, pp. 284-285. The authors explain:
“Whereas most mammals (including common species such as dogs and mice) and most other primates (excepting spider monkeys) have a penile bone, human males lack this bone and must rely on fluid hydraulics to maintain erections. This is not an insignificant bone…. One of the creation stories in Genesis may be an explanatory myth wherein the Bible attempts to find a cause for why human males lack this particular bone. Our opinion is that Adam did not lose a rib in the creation of Eve. Any ancient Israelite (or for that matter, any American child) would be expected to know that there is an equal (and even) number of ribs in both men and women. Moreover, ribs lack any intrinsic generative capacity. We think it is far more probable that it was Adam’s baculum that was removed in order to make Eve. That would explain why human males, of all the primates and most other mammals, did not have one.”
(Thanks to investigator Ann Starr for bringing this to our attention.)