The Insight
If you had asked anyone in 7th-century Arabia where the fluid of reproduction comes from, the answer would have been obvious: the genitals. That is where it exits the body, and direct observation confirms it. The verse points somewhere else. «He was created from a spurting fluid, proceeding from between the backbone and the ribs.» Modern embryology revealed why this is less strange than it sounds. The testes, the organs that produce that fluid, do not begin life in the scrotum. In the developing embryo they form high in the body, on the back wall of the abdomen near the kidneys, in the region between the spine and the ribcage. Only later do they descend through the inguinal canal to the scrotum. And the connection is permanent: even in the adult, the testes' main blood vessels and nerves still run all the way up to that original location between the backbone and the ribs, because that is where the system was built. The visible anatomy says the genitals. The hidden anatomy, traceable only through dissection and the study of fetal development, places the origin and supply of the reproductive fluid between the backbone and the ribs, exactly where the verse points. None of this was knowable in the 7th century, when the only available evidence pointed the other way.