Accessing animal skulls for cerebrospinal fluid and eye fluid could have been a significant source of vitamin C for early humans.

“we had just this the complete access to skulls of animals only hyenas can access the skull they're the only animal in the savanna they had strong enough jaws to crack open a skull marine needs about 20 milligrams of vitamin C maybe 18 for three and a half ounces and and cerebral spinal fluid is contains about 40 milligrams per liter now cerebra spinal fluid there's Anna Todd what we were just constantly scavenging all these skulls because no no other animal had access to it and we were also drinking the cerebral spinal fluid and the fluid in the eyes who knows how much vitamin C were we were getting”