Skin Pigmentation: Biology, Culture, and Societal Norms slide version 1.0

1. Skin Pigmentation: Biology, Culture, and Societal Norms slide version 1.0 www.evo-ed.org

2. Skin PigmentationCulture and Biology Learners will be able to: • Assess the idea of race in terms of culture. • Assess the biological definitions of race and subspecies in terms of biology. • Explain the role the brain plays in racial categorization. • Propose ways to mitigate the negative effects of racial categories.

3. The Idea of RaceCultural Aspects What’s a culture? A common definition is the shared social attributes of a group. These attributes include beliefs, values, and customs. Ancient cultures generally shared a language. These values lead to a group cohesiveness and a strong sense of “Us”.

4. Cultural Aspects of Race • Cultures categorize groups of people (more about this later). One category is race, which leads to racial profiling, racial identity, racial prejudice, racial pride, etc. In many modern cultures, skin color is the basis for defining racial groups. • Words matter; this is especially important when definitions are ambiguous or context dependent, as is the case for race.

5. Is There a Cultural Definition of Race? The cultural definition of race is variable, fluid and context dependent. Race is pretty much what people say it is: it’s an idea. Different cultures, societies and even individuals use their own parameters to categorize others and themselves by race. Often, race is defined by skin color.

6. Cultural and Social Aspects of Race • The use of the word race in human affairs is common. Race is a proxy to label people in terms of economics, politics, social hierarchies, status, the way they look, identity of self and others, etc. Since cultures vary in the importance they attach to each of these attributes, the meaning of race is fluid and arbitrary. • Additionally, historical conditions, most egregiously slavery, have had a strong bearing on how we view and treat each other as races.

7. Arbitrary Nature of Race The arbitrary nature of race is shown by the censuses in different countries having different bins when trying to describe distributions of people in a population. These categories pigeonhole people by ethnicity (Hispanic, Asian) and/or a shade of skin color. These bins are fuzzy and changeable.

8. Arbitrary Nature of Race • Thus, although censuses are very important for modern governments, the terms and categories used are variable and often are the result of historical circumstance. For example, the U.S. and Brazilian census categories over time are shown on the next two slides from Nobles 2000. • “The categories are themselves intellectual products, social markers, and policy tools.” • “There are no simple, obviously right or obviously wrong answers to the question of whether American or Brazilian censuses should continue to count by race or color.”

9. Arbitrary Nature of Race – U.S.

10. Arbitrary Nature of Race – Brazil

11. Arbitrariness:Fraternal Twins These two young women, Lucy and Maria, were born at the same time to the same mother and father. They have other siblings, each with distinctive skin color and hair texture. Lucy identifies herself as white and Maria identifies herself as black. They are using cultural, not biological norms, to define their identities. Lucy and Maria

12. Biology and Race Many geneticists, neurobiologists, anthropologists, among other scientists, agree that race is a social, rather than biological construct in humans. There are no scientific bases on which to assign people to a race. This perspective guides the information presented here.

13. Racial Concepts in Genetics Research "It's a concept we think is too crude to provide useful information, it's a concept that has social meaning that interferes in the scientific understanding of human genetic diversity and it's a concept that we are not the first to call upon moving away from” – Dr. Michael Yudell

14. What is the Biological Definition of Race? Some biologists, primarily entomologists and plant biologists, apply the term “race” to populations that vary significantly from one another. These variations include chromosomal, genetic, geographical and/ or physiological differences.

15. Races of Rhagoletispomonella The apple race The hawthorn race

16. SubspeciesDogs and Wolves For a long time vertebrate biologists have used another term: subspecies. For example, many canine geneticists view dogs (Canis lupus familiaris) as a subspecies of wolf Canis lupus). There are no subspecies designations for dogs, although adults of different breeds can range in size from under a pound to over 300 pounds.

17. An Example of Subspecies: The Beach Mouse Peromyscuspolionotus

18. How to Define a Subspecies? Subspecies can be defined as either: 1) Having sharp boundaries, defined by genetic differences. These differences are determined by comparing genetic information from sampled individuals in one population to that of individuals in another. When mapped across populations, genetic differences are not continuous across a sampled area. 2) Consisting of separate evolutionary lineages within a species; that is multiple lineages are found within a speciesas determined by phylogenetic analyses.

19. Genetic DifferencesHumans A genetic survey of 52 human populations, sorted into five global “races”, showed that the differences: • the differences among individualsin the same population was 93.2% • the differences among local populations within the same “race” was 2.5% • the differences among “races” was was 4.3% First Cousins

20. Genetic DifferencesChimpanzees A similar analysis for chimpanzees (5 populations and 3 “races”) showed that: • the differences among individuals in the same population was 64.2% • the differences among local populations within the same “race” was 5.7% • the differences among “races” was 30.1%

21. Genetic Differences:Chimps and Humans • Most of the differences in the human genes surveyed are among individuals within a given populations. There is little difference when comparing populations and “races”. • By comparison, chimpanzees have much less genetic variation among individuals in a population and a lot more differences among “races”.

22. Separate Evolutionary Lineages FST values provide information about genetic boundaries and separate lineages within a species. They vary from 0.0 to 1.0 and indicate the following when comparing two populations: FST = 0: They are freely interbreeding and show insignificant variation in genetic information. FST = 1: They are very different from one another in genetic information. They may be on their way to becoming separate species. Generally speaking, FST values of 0.25 and above indicate the possibility that one of the populations is a subspecies.

23. Separate Evolutionary Lineages The designation of a subspecies suggests discontinuity in both genetic information and geography: separate evolutionary lineages. Graphing FST values for human populations against geographic distance produces this graph: Geographic Distance (in km)

24. Separate Evolutionary Lineages?No The straight, continuous line without any “jumps” in FST values indicates that there were no separate lineages as humans expanded throughout the planet. Add in the low genetic variation between populations and the propensity of human beings to interbreed as migrations occurred and reoccurred and one is left to conclude that Homo sapiens is lacking in genetic diversity. Conclusion? There are no biological races or subspecies of human beings.

25. We Are All the Same This preceding information is critical. It really matters to human affairs that our notion of race is not dependent on genetic information – we are all the same. Race is an idea. Why is the very human propensity to categorize people people by race both universal and persistent? Answer: We have a big brain that insists on discerning the differences in things and putting them in categories. Cultural identity is linked to categorization.

26. What Humans Do:Categorize Things Children like to play with objects that they can sort and categorize by shape, size and color. This toy encourages identification by color, size and spatial relationships.

27. What Humans Do:Categorize Ideas Educators have long used Bloom’s taxonomy to categorize the kinds of knowledge they expect students to acquire and use. This representation of Bloom’s taxonomy uses the same colors as the children’s toy.

28. What Humans Do:Categorize Living Things Humans use hierarchical representations to help classify living things. This simple color coded representation helps people to put living organisms into recognizable bins.

29. What Humans Do:Categorize Frogs H. sapiens can make fine discriminations based on surface features. We can see differences among these Northern leopard frogs, Lithobatespipiens. Frogs simply see other frogs just like themselves. Northern leopard frogs are much more diverse genetically than human beings. A small passel of Lithobatespipiens

30. The Categorizing Brain • We also discriminate and categorize other human beings based on surface features, as well as on another’s actions and group affiliations. • We have a fancy brain with input and outputs that allow us to do that. Sometimes this is good, sometimes this is not so good, depending. Either way it allows for categorizing groups as Us and Them. • How our brain accomplishes this is incredibly complex. We’ll explore two parts of the brain key to understanding how we come to separate Us from Them.

31. The Amygdala The limbic system of the brain mediates emotion. The biggest player is the amygdala, which mediates aggression, fear and anxiety. This fear is both innate and learned. These emotions are invoked below conscious detection.

32. The Amygdala • Certain social situations activate the amygdala, particularly those with ambiguity and uncertainty. These situations can lead to vigilance and distrust. This is the first step in determining “Them”. • The amygdala can respond to scary stuff without frontal processing (see next slide). These responses are subliminal, “knee jerk”, not accurate and sometimes inappropriate. A generic Fraidy Cat

33. The Frontal Cortex The frontal cortex is where we take information from the amygdala and process it. It’s the “decider”, mediating responses to social situations.

34. The Frontal Cortex The frontal cortex response is automatic in that the “decision” is made more than half a second before a person is aware of having made one. The frontal cortex also sorts things out - follows rules and puts things in categories - when presented with information from the amygdala, other neural inputs, and hormones.

35. Frontal Cortex There are two parts of the frontal cortex key to “deciding”. One part is rational and unsentimental – the dorsolateral region. The other is important for making social and emotional decisions – the ventromedial region. Bottom line, the frontal cortex integrates emotional and cognitive aspects of social life as well as communicating with other parts of the brain. The bright yellow gears represent the frontal cortex.

36. The Brain and Them • Them initially activate the amygdala, that part of the brain involved with perceiving fear and potential threats. This “knee jerk” response is forwarded to the frontal cortex, where cooler, more analytical brain parts prevail. • As the frontal cortex processes this information, the amygdala is dampened and Us/Them dichotomies repressed. • However, this processing is highly variable among individuals and has both a biological basis and and strong cultural bias.

37. Us and Them The amygdala and frontal cortex allow humans to respond to and categorize other humans into Us and Them. We often have many categories of Us and Them in our lives. Some categories are: • Gender • Religion • Faces • Skin color • Sports teams • Language • Customs • Clothing • Income • Clubs • Etc., etc., etc.,

38. Attributes of Us and Them How we view Us: • Loyal, Smart, Worthy, Moral, Same values And most importantly, as individuals. Members of Us have shared obligations and responsibilities. How we view Them: • Threatening, Angry, Immoral, Simple, Different values And most importantly, as a monolithicgroup.

39. Them: Skin Color Homo sapiens is a homogeneous species. However, the categorizing brain easily detects surface features and the primary one is skin color. Skin color only indicates the amount of eumelanin and pheomelanin produced, which is tied to an individual's ancestry. As populations and cultures began to run into each other, skin color became, in some cases, one of the foundations of cultural definitions of race.