The genetic material inside the mitochondrian, an energy-producing unit of a cell, which has been studied to calculate the antiquity of modern humans. Some mtDNA studies suggest that modern humans arose first in Africa around 200,000 years ago. Investigations of human mitochondrial DNA reveal that the variation among modern human populations is small compared, for example, with that between apes and monkeys, which points to the recency of human origin. Research also points out that there is a distinction between African and other human mitochondrial DNA types, suggesting the substantial antiquity of the African peoples and the relative recency of other human populations.