Average body temperature among Americans has dropped about 0.02 °C (0.05 F) every decade since the early 1800s and 0.03 °C every decade since 1960
Mackowiak PA, Wasserman SS, Levine MM. A Critical Appraisal of 98.6°F, the Upper Limit of the Normal Body Temperature, and Other Legacies of Carl Reinhold August Wunderlich. JA
The ASS gene, ASS deficiencies and a few other things
Argininosuccinate synthetase is an enzyme that in humans is encoded by the ASS1 gene. Beaudet AL, O’Brien WE, Bock HG, Freytag SO, Su TS (Mar 1986).