Serum Uric Acid Level

Serum uric acid levels play a role in the development of gout in humans, with crystallization occurring due to oversaturation and deposits in joints causing arthritis. This condition has not so far been described in non-human primates. Serum uric acid levels decrease with age in the chimpanzee.  Serum Uric acids levels tend to be higher in apes and humans, than in monkeys, with humans tending to have the highest levels. Two independent mutational events seem to have resulted in the loss of urate oxidase during ape evolution. The mechanism and biological reason for this loss remain unknown. Because the disruption of a functional gene by two independent events in different evolutionary lineages is unlikely to occur on a chance basis, it is reasonable to suggest that the loss of urate oxidase had evolutionary advantages. One possibility is that it provided increased levels of uric acid to act as an antioxidant, to deal with the fact that longer life-spans result in longer exposure to oxidant damage.

Wu XW, Muzny DM, Lee CC, Caskey CT. Two independent mutational events in the loss of urate oxidase during hominoid evolution. J Mol Evol. 1992 Jan;34(1):78-84.