1. Modern humans (Homo sapiens) How is human diversity perceived? Traditionally as distinctly different races

2. Many attempts to classify human diversity Carleton Coon. 1965. The Living Races of Man Five races proposed: –Caucasians –Asians –Indiginous Australians –Black Africans –San or Bushmen from Africa

3. How do biologists perceive races in non- human species? A biological race = a subspecies. Phenotypically diagnosable populations occupying allopatric subdivisions of the range of a species. These populations have accumulated different mutations. Therefore, they express different fixed characteristics.

4. Example of subspecies Colaptes auratus cafer Colaptes auratus auratus

5. Example of subspecies: ratsnake (Elaphe obsoleta Discordant character Systems: also found in humans Genetic differences don’t coincide with color pattern differences

6. Human race concept. There is no satisfactory biological definition of a human race! Misconception: there are character states unique to particular groups of humans The characters traditionally used are quantitative characters with continuous variation.

7. “Racial” characters are quantitative characters continuous characters e.g. skin color Phenotypic expression in and among populations generally fits a normal distribution

8. A common “racial” characteristic is skin color.

9. Melanosomes

10. All individuals have approximately the same number of melanocytes. Therefore, what is the basis of skin color differences? Can “races” be recognized based on skin color?

11. These groups easy to identify because of non-overlapping variation. Gaps 685 nm

12. Skin color in 22 human populations Samples of males Mean +/- one standard deviation