Fitzpatrick Scale and Evolution of Skin Tones

00:01 Welcome to our lecture on the differences between melanin rich and melanin poor skin types. The classification of the skin is based on its reaction to exposure to sunlight, and this is based on the Fitzpatrick photo skin type scale.

00:22 Type one is typical pale white skin, blue green eyes, blond red hair and its ability to turn so type skin type one photo.

00:35 Type always burns and does not tan.

00:39 Type two is first skin with blue eyes and bends easily and it actually turns very poorly. Type three little darker skin, white and tans after initial burn.

00:55 Type four is light brown skin and it bends minimally and turns easily.

01:02 Type five refers to brown skin, which rarely burns and tans darkly and easily on exposure to sunlight. Type six is dark brown or black skin and it doesn't burn, never burns, and always turns and turns very dark.

01:22 So these are the features that we look at when we look at the Fitzpatrick Metric scale prototype. The typical features that have gone through, as well as the ability of the skin to turn on exposure to sunlight.

01:38 However, the Fitzpatrick Skin Phototype scale is widely used, but it has been criticized for its limited precision, more so in capturing the broader spectrum of skin colors between types four and six.

01:57 As you can see on these pictures, there's a wide range of differences between a skin type four and six.

02:05 So how did our skin color evolve? It evolved as a protective adaptation of early humans who had shed their fur, providing a defense against skin cancer in the intense tropical sunlight.

02:22 This, however, had some disadvantages.

02:27 As humans migrated from the equator, surplus melanin became a drawback.

02:34 It caused reduced vitamin D production in regions with lower UV radiation.

02:41 And as an evolutionary response, there was reduction in pigmentation as an adaptive response, which is better suited for lower UV radiation levels in new environments.