The Gentoo Penguin is one of three species in the genus Pygoscelis. Mitochondrial and nuclear DNA evidence suggests the genus split from other penguins around 38 million years ago, about 2 million years after the ancestors of the genus Aptenodytes. In turn, the Adelie Penguins split off from the other members of the genus around 19 million years ago, and the Chinstrap and Gentoo finally diverging around 14 million years ago.Males have a maximum weight of about 8.5 kg (19 lb) just before molting, and a minimum weight of about 4.9 kg (10.8 lb) just before mating. For females the maximum weight is 8.2 kg (18 lb) just before moulting, but their weight drops to as little as 4.5 kg (10 lb) when guarding the chicks in the nest. Birds from the north are on average 700 g (1.5 lb) heavier and 10 cm (4 in) taller than southern birds Gentoo penguin reaches 75–80 cm. They are the fastest underwater swimming penguins, reaching speeds of 36 km/h. Gentoo are adapted to very harsh cold climates.