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Anth 1026 > Ch 4 Human Variation and Adaptation > Flashcards

Ch 4 Human Variation and Adaptation Flashcards

1
Q

Johann Friedrich Blumenbach

A
  • Classified humans into 5 races

- “White, yellow, red, black, brown”

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2
Q

The Concept of Race

A
  • In biology a category with subspecies
  • Based on distinctive physiological, morphological, and ecological features
  • Easily observed differences among humans from major geographic areas
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3
Q

The Concept of Race: What’s wrong with that? (2)

A
  • Look at its enormous sociocultural significance

- Look at why it doesn’t hold up biologically

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4
Q

The Concept of Race: Where do we draw the Line?

A
  • Easy to see extremes – what about all the variation in the middle?
  • “Falls apart” when we start to draw lines
  • Occurs on a continuous spectrum, not ‘present vs. absent’ but ‘more vs. less’
  • Difficult whether we divide people into 3, 5 or even 30 ‘micro’-races
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5
Q

The Concept of Race: Who gets to draw the Line?

A
  • Many examples of dominate group using race for oppression, subjugation, sterilization and genocide
    Ex. eugenics movement
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6
Q

Human Polymorphisms

A
  • Loci with more than one allele (ex. ABO blood type)
  • Examining single traits can help when looking at natural section or gene flow, but are limited
  • Studying several traits simultaneously helps us understand relationships between populations
  • Examining these traits can tell anthropologists lots about our history
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7
Q

Alberta Sexual Sterilization

A
  • Drafted under the guises of protecting the gene pool
  • Sterilizing mentally unwell people to prevent the passing of mental illness
  • Criminal behaviours, mental illness, prostitution etc. all deemed mental illnesses
  • There was a fear that the gene pool would be weakened if these “not normal” people were allowed to “breed”
  • Lied to about the fact they would be ‘sterilized’ during another operation (ex. Dental work)
  • Women, men, children
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8
Q

Considerations about Race:

Human Populations are Heterogeneous

A
  • We recognize there is variation between different human populations
  • Discrediting the notion of race does NOT mean scientists are suggesting there are no phenotypic or genetic differences
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9
Q

Considerations about Race:

Polygenic traits are difficult to measure accurately

A
  • Skin pigmentation is difficult to measure accurately
  • What/ how are you counting?
  • Hard to determine how much was genetic versus how much was environmental
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10
Q

Considerations about Race:

Discrete Boundaries

A
  • A continuously varying trait has no inherently meaningful boundaries!
  • Boundaries are always arbitrary and thus subject to bias
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11
Q

Considerations about Race:

Traits are not linked

A
  • Features ascribed to different races do not co- occur together – they are not phenotypic or genotypic clusters
  • Ex skin color, hair colour & texture, facial physiognomy all occur on different chromosomes through different alleles, therefore they do not co vary
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12
Q

Considerations about Race:

Specific # of traits cannot define a race

A
  • How many features are necessary to assign race?
  • It is arbitrary; there is no agreement on how many differences it takes
  • No single feature can clearly assign race
  • No ‘race’ has exclusive possession of any particular variant of a gene or genes
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13
Q

Considerations about Race:

Genetic Diversity

A
  • How much genetic diversity actually matters?

- Lewontin (1972) study – over 85% of genetic diversity occurs among individuals within populations

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14
Q

Considerations about Race:

Gene flow

A
  • Populations are genetically “open,” meaning that genes flow between them
  • No fixed racial groups can ever exist
  • Humans have always inbred
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15
Q

Cline

A
  • A gradient over which the frequency of expression of a trait changes
  • Create a map of changes in trait expression based on measured frequencies
  • “There are no races, there are only clines.”
  • Ex. sickle-cell anemia cline
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16
Q

Solar Radiation:

Darker Skin

A
  • In areas closer to the tropics, natural selection favoured deeply pigmented skin
  • Early Hominins lived in tropics, with minimal shade, and didn’t wear clothing
  • Environment favoured high production levels of melanin (to protect from UV rays)
17
Q

Solar Radiation:

Lighter Skin

A
  • As Hominins migrated they entered colder, cloudy environments
  • The dark pigment blocking UV rays also blocked vitamin D, so natural selection began favouring lighter pigmented skin
18
Q

Lactose Tolerance

A

Recent human evolution
- The ability to digest lactose depends on the enzyme lactase
- All children have this ability but in many it is lost by adolescence
• Breastfed when they were younger, stopped as they grew up

19
Q

Lactose Tolerance:

African vs. European

A

European
• In European cultures it was common to drink milk past childhood, so most adults kept this enzyme
African
• In African cultures they did not, so they tend to be less tolerant to lactose

20
Q

Thermal Environment

A
  • Mammals and birds have physiological mechanisms to maintain constant body temp
  • Human habitats range from 120° F (49° C) to -60° F (-51° C).
21
Q

Acclimatizations

A
  • Physiological responses to changes in the environment that occur during an individual’s lifetime
  • Responses may be temporary or permanent
  • Subject to evolutionary factors such as selection
22
Q

Human’s Response to Heat

A
  • Long term adaptations to heat evolved out ancestors
  • Sweat Glands and Loss of Body Hair
    • Distributed throughout body, making cooling easier
    • Loss of hair helped
23
Q

Human’s Response to heat:

Vasodilation

A
  • Capillaries near the skin’s surface widen to increase blood flow
  • Allows the skin to radiate heat
24
Q

Bergmann’s Rule

A

“Body size changes in different climates”
In cold, body size is large
In warm, body size is small
- Larger bodies have smaller surface area to volume ratios

25
Q

Allen’s Rule

A

In cold, body is more rounded and compact

In warm, body size is more linear
- Round forms have smaller surface area to volume ratios

26
Q

Human’s Response to Cold:

Short Term

A
  • Increase heat production
  • Enhance heat retention
  • Ex. Shivering
    • Short term response to generate heat, but energetically expensive
27
Q

Human’s Response to Cold:

Long Term

A
  • Seen mainly in groups acclimated to living in cold environment
  • Maintain high metabolic rate
28
Q

Human’s Response to Cold:

Vasoconstriction

A
  • Narrowing of blood vessels to reduce blood flow
  • Short term response to retain heat and conserve energy
  • *Concern is frostbite
29
Q

High Altitude:

Factors (5)

A
  1. Hypoxia (reduced available oxygen)
  2. Intense solar radiation
  3. Cold
  4. Low humidity
  5. Wind
30
Q

High Altitude:

Growth& development

A
  • Larger heart size
  • Greater lung capacity
  • More efficient diffusion of oxygen to body tissues
31
Q

High Altitude:

The Indigenous Peoples of Tibet

A
  • Lived at ~12,000 ft for many thousands of years
  • Burn glucose in a way that permits more efficient use of oxygen
  • Alterations in maternal blood flow to placenta
  • Strong example of natural selection in humans (happened quickly over 4000 years)
32
Q

Infectious Disease:

Causes- Biological& sociocultural (6)

A
  • Rural vs. urban
  • Agriculture
  • Exposure/consumption of domesticated animals
  • Socioeconomic status
  • Living conditions, sanitation
  • Religious/ideological beliefs
33
Q

HIV/AIDS:

Stats and dates

A
  • First confirmed case in US in 1981
  • Present at least as far back as 1959 in West Africa
  • 95% of people with HIV are in the developing world
  • In 2012 estimated that 28 million people are living with HIV (World Health Organization)
34
Q

HIV/AIDS:

Origin

A
  • Interspecies transfer infection

- HIV 1 evolved from simian immunodeficiency virus (SIV) found in gorillas, chimpanzees and African monkeys

35
Q

HIV/AIDS:

Genetics

A
  • Altered receptor site in immune cells prevents HIV from entering
  • Mutation found in about 10% of people with European decent
  • *** Too recent of a disease for there to be evolutionary changes
  • Didn’t make sense that some people had the mutation preventing it
  • Would have to have come from some previous disease
  • Bubonic plague (Black Death; 14th C)??
  • Smallpox (17-18th C)??
36
Q

Smallpox

A
  • The only disease considered to be eliminated as a result of medical technology
  • More common in people with type A or AB blood, than those with type O blood

Why? We aren’t sure

  • The immune system of those with type A blood may not see it as a threat
  • As a result, their body would not fight as effectively against small pox
37
Q

Impact of Infectious Disease:

& Antibiotic Resistance

A
  • # 1 cause of death before 20th century
  • Since the 1940s, antibiotics have reduced mortality
  • Between 1980 and 1992 deaths from infectious disease increased by 58%.
  • Could be a result of overuse of antibiotics
  • Bacteria and viruses evolve quickly (short lifespans) and become resistant to antibiotics

Anth 1026 (9 decks)

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