Racial Classifications and Anthropology

Lecture 12: Racial Classifications

• Racial classifications are rooted in European colonialism, ethnocentrism, and power dynamics
• Early scientists tried to classify humans into fixed racial categories, forming the basis for scientific racism and typological thinking
• Polygenism vs monogenism aimed to explain the origins of human variation
• Typology and anthropometry were used to justify racial hierarchies but were later debunked
• Franz Boas emphasized environmental influences and phenotypic plasticity
• Modern genetics indicate more variation within groups than between them
• Race is now recognized as a social construct
• The Tuskegee Syphilis Study exemplifies unethical race-based science
• Anthropology focuses on evolutionary origins and rejects racial classification

Key Terms & Definitions

• Ethnocentrism: Belief in the superiority of one's own culture
• The Great Chain of Being: The idea that all life exists in a hierarchy
• Carolus Linnaeus: Created early human classifications based on geographic and physical traits
• Johan Friedrich Blumenbach: Created 5 racial categories, believing in a common origin but with environmental differences
• Scientific Racism: Belief that races are biologically distinct and unequal
• Polygenism: Human races come from separate origins
• Monogenism: Human races come from a single origin
• Typology: Categorizing humans into "ideal" racial types based on physical traits
• Anthropometry: Measurement of the human body, especially the skull
• Cranial Index: (Skull width / skull length) × 100, once wrongly linked to intelligence
• Eugenics: Movement to improve the human race via selective breeding
• Franz Boas: Anthropologist who challenged racial typologies and emphasized environmental impacts and plasticity
• Plasticity: The ability of traits to change due to environmental factors
• Cline: Gradual change in traits or genes across geography
• Institutional Review Board (IRB): Reviews human subjects research for ethical standards
• Tuskegee Study: An unethical study where African American men were denied syphilis treatment

Repeated Themes

• Race is a social construct, not biological
• Classification systems were used to justify inequality
• Typological thinking is flawed because more variation exists within groups than between them
• Franz Boas and modern anthropology changed how we think about race

Lecture 13: Genetic Variation

• Continues discussion that rejects race as biologically valid
• Genetic variation reviewed emphasizes the social construction of race
• Genetic ancestry tests and racial-genetic determinism are problematic
• Embodiment theory explains how social inequality can produce biological effects
• Critiques of using race to explain genetics or health disparities noted
• Race cannot be biologically defined, despite consequences of structural inequality

Key Terms & Definitions

• Race: Socially and culturally constructed idea used to group people with perceived biological traits
• Ethnicity: Group identity based on cultural, linguistic, religious, and geographic factors
• Population: A group of individuals that interbreed and share a gene pool
• Clinal Variation (Cline): Gradual change in trait or gene frequency over geographic space
• Concordance: Traits that vary together, such as height and weight
• Discordance: Traits that vary independently, for instance, skin color and intelligence. Most racial traits are considered discordant
• Genetic Determinism: Belief that genes alone define traits, behavior, and identity
• Racial-Genetic Determinism: False belief that racial groups have distinct, meaningful biological differences due to genetics
• Morbidity: Rate of disease in a population
• Mortality: Rate of death in a population
• Embodiment: Biological incorporation of social and environmental experiences across a person’s life (Krieger 2005)
• Plasticity: An organism's ability to adapt biologically to environmental conditions

Repeated Themes

• Race is socially constructed
• Genetic variation is clinal and discordant, making racial categories meaningless
• More variation exists within racial groups than between them
• Only approximately 0.1% of human DNA varies between individuals
• Health disparities by race stem from social inequality, not biology
• Embodiment explains how lived experiences shape biology over time

Critiques of Race as a Genetic Category

• Human variation is clinal without clear boundaries
• Traits used to define race are discordant
• Variation is widely shared, being more prevalent within groups than between them

Problems with Genetic Ancestry Tests

• Inaccurate for tracing ancestral locations
• Overrepresentation of European populations
• Promotion of false objectivity and genetic determinism
• Lacking information on culture, history, or lived experience

Models of Human Biological Variation

• Social Determinants of Health Model links social conditions to health outcomes
• Intergenerational Inheritance of Health Model is influenced by DOHaD and focuses on how early-life environments impact long-term health
• Timescales of Adaptation Model describes how humans adapt across different timescales
  • Allostasis: short-term physiological regulation
  • Acclimatization: medium-term adjustments
  • Developmental Adaptation: changes during growth
  • Genetic Adaptation: long-term evolutionary changes
• Human Energy Allocation Model: biological energy is finite and distributed across competing functions

Metabolic Health

• Risk defined for cardiovascular disease and type II diabetes
• includes indicators such as hypertension, dyslipidemia, hyperglycemia, subclinical inflammation, and obesity.

Adipose Tissue Types

• Subcutaneous Adipose Tissue (SAT) is less inflammatory and found in hips/thighs
• Visceral Adipose Tissue (VAT) is more inflammatory and surrounds organs

Human Diet and Health

• Hunter-Gatherer Diets: diverse, fiber-rich, low glycemic index with low chronic disease rates
• Nutrition Transition: a shift from traditional to market-based diets and sedentary lifestyles that leads to a dual burden of disease, with under-nutrition plus over-nutrition; and a thrifty phenotype hypothesis, where early under-nutrition leads to metabolic efficiency and increasing chronic disease risk

Important Terms and Concepts

• Social Determinants of Health shape health via social, economic, and environmental
• Intergenerational Inheritance of Health explains adult disease risk through prenatal/infant conditions
• Adaptation describes biological changes that improve survival due to environmental conditions
• Timescales of Adaptation Model showing timescale adaptation occurs over
  • Homeostasis is the maintenance of internal balance
  • Allostasis consists of rapid physiological changes
  • Acclimatization involves temporary changes.
  • Developmental Adaptation produces long-term changes.
  • Genetic Adaptation yields heritable changes for natural selection
• Human Energy Allocation assigns limited energy be split among functions
• Metabolic Health includes the risk level for heart disease and diabetes
• Subcutaneous Adipose Tissue (SAT) stores fat under skin and is less harmful
• Visceral Adipose Tissue (VAT) accumulates fat around organs that is more harmful
• Differences / Commonalities in Hunter-Gatherer Diets are diversified, low in sugars and high in fiber
• Food Security describes consistent access to safe/nutritious food
• Dietary Adequacy shows alignment of nutrient intake with body needs
• Physical Nutritional Status describes health state via physical and biochemical measures
• Body Mass Index (BMI) details a weight-to-height ratio
• Dual Burden of Disease lists coexistence of under/over-nutrition

Lecture 15: Psychosocial Stress

• Psychosocial stress affects human biology related to chronic disease, adaptation, and the endocrine system
• Modern stressors connect to evolutionary biology via transition, stress physiology, and chronic cortisol exposure

Key Terms and Concepts

• Epidemiological Transition is the shift from infectious to non-infectious diseases
  • Pre-transition: low life expectancy and high child mortality
  • Post-transition: longer lives but a rise in chronic illness
• Homeostasis is the body’s attempt to maintain internal conditions
  • Disruption of homeostasis sparks stress
• Allostasis is the process by which the body maintains stability, adjusting physiology based on demands
  • Acknowledges biological "set points."
• Stressor is any stimulus that disrupts balance/elicits a physiological response
• Acute stress: short-term stress response
• Chronic stress is an ongoing that can lead to health deterioration
• Autonomic Nervous System (ANS) regulates involuntary functions
  • Sympathetic Nervous System (SNS) activates fight-or-flight
  • Parasympathetic Nervous System (PNS) calms the body
• Sympathetic Nervous System triggers release of epinephrine and norepinephrine and inhibits digestion/reproduction
• Parasympathetic Nervous System promotes relaxation, digestion, and recovery
• Neurotransmitter is a messenger released by neurons
  • Epinephrine is released in stress responses
• Hormone is a messenger released into the bloodstream.
  • Cortisol is involved in stress
• HPA Axis (Hypothalamic-Pituitary-Adrenal Axis) is the central pathway
  • Hypothalamus releases CRH
  • CRH stimulates the pituitary gland to release ACTH
  • ACTH prompts the adrenal glands to release cortisol
• Cortisol increases blood sugar, suppresses the immune system, regulates metabolism, and can disrupt health

Historical Figures

• Robert Sapolsky: wrote “Why Zebras Don’t Get Ulcers,” and researched chronic stress, determining how humans become vulnerable due to stress

Effects of Chronic Stress

• Cardiovascular: High blood pressure/vessel damage
• Digestive: IBS/acid sensitivity
• Metabolic: Cravings and increased visceral adipose tissue (VAT)
• Immune: Suppressed immunity

Combating Stress

• Therapies, exercise, and meditation
• Research links social determinants of health to biological markers

Lecture 16: UV Radiation

• Explores trade-offs and genetic adaptations to UV environments, and focuses on melanin, folate, and vitamin D as well as the tanning response

Key Terms and Concepts

• Melanin is a chemical compound that protects against UV radiation
  • Eumelanin provides brown/black pigmentation with UV protection
  • Pheomelanin gives red/yellow tones and does NOT protect against UVR
  • Neuromelanin is found in brain neurons
• Melanocyte are skin cells that produce melanin
• Pheomelanin is responsible for reddish pigment so it offers poor UV protection
• Eumelanin provides dark pigmentation
• UV Radiation is a component of sunlight
  • Risks: sunburn, skin cancer, eye diseases, aging, and folate degradation
  • Benefits: Vitamin D production
• MC1R Gene regulates melanocortin 1 receptor
  • influences skin/hair/eye color
  • mutation increases UV vulnerability
• Folate: A B-vitamin for DNA synthesis
  • depleted by UVR
• Vitamin D is produced due to UVB exposure
  • supports absorption
• Tanning Response is a adaptation where melanocortins stimulate pigment production
  • A UV-induced stress response
  • UVB-induced tans offer some protection

Genetic Adaptations

• Skin pigmentation evolves in response to UVR intensity
  • High intensity leads to darker skin
  • Low intensity leads to lighter skin

Lecture 17: Cold Stress

• Focuses on biological, physiological, plus developmental mechanisms. Covering aspects of body morphology to help heat levels.

Key Terms and Concepts

• Allen’s Rule: Animals adapted to warmth have longer limbs that allow heat dissipation
• Bergmann’s Rule: Animals in cold environments are larger, improving heat retention
• Thermogenesis generates body heat using shivering/shivering mechanisms
• VASOCONSTRICTION AND VASODILATION
  • Vasoconstriction reduces heat loss
  • Vasodilation releases heat
• NST (Non-Shivering Thermogenesis) involoves production without muscle movement
• BAT (brown adipose) burns energy
• Acclimatization to Cold includes physiological adjustments involving higher BMR or basal methodic rate
• Developmental Adaptations to Cold occur during early development
• Adaptations to climate passed down
• Allostatic responses are immediate to help adapt