The colour and size of lions' manes was long thought to be a sufficiently distinct morphological characteristic to accord a subspecific status to lion populations. Mane development varies with age and between individuals from different regions, and is therefore not a sufficient characteristic for subspecific identification. The size of manes is not regarded as evidence for Barbary lions' ancestry. Instead, results of mitochondrial DNA research support the genetic distinctness of Barbary lions in a unique haplotype found in museum specimens that is thought to be of Barbary lion descent. The presence of this haplotype is considered a reliable molecular marker to identify Barbary lions in captivity. Results of a long-term study on lions in Serengeti National Park indicate that ambient temperature, nutrition and the level of testosterone influence the colour and size of lion manes. Barbary lions may have developed long-haired manes, because of lower temperatures in the Atlas Mountains than in other African regions, particularly in winter.