Evolutionary loss of ascorbic acid synthesis: how it may have enhanced the survival interests of man.

It is proposed that the loss of ability by humans to synthesize ascorbic aicd may have markedly enhanced the survival opportunities of early man living in a malarial infested environment. This hypothesis is based on biomedical evidence which indicates that glucose-6-phosphate dehydrogenase (G-6-PD) deficient individuals display enhanced sensitivity to ascorbic acid induced hemolysis which has been fatal at sufficiently high doses and that the G-6-PD deficient trait has been selected for in malarial environments.