Dark skin gives seven to eightfold protection against DNA damage, but even the darkest skin colour cannot protect against all damage to DNA. Dark skin offers great protection against UVR because of its eumelanin content, the UVR-absorbing capabilities of large melanosomes, and because eumelanin can be mobilized faster and brought to the surface of the skin from the depths of the epidermis. For the same body region, light- and dark-skinned individuals have similar numbers of melanocytes (there is considerable variation between different body regions), but pigment-containing organelles, called melanosomes, are larger and more numerous in dark-skinned individuals. Keratocytes from dark skin cocultured
Chameleon heat more efficiently, then a lighter grey colour to reflect light during the heat of the day. It may show both colors at the same time, neatly separated left from right by the spine. For a long time it was thought that chameleons change colour by dispersion of pigment-containing organelles within their skin. However, research conducted in 2014 on panther chameleons has shown that pigment movement only represents part of the story. Chameleons have two superimposed layers within their skin that control their colour and thermoregulation. The top layer contains a lattice of guanine nanocrystals, and by exciting this lattice