Ch 4 Human Variation and Adaptation

Question 1

Johann Friedrich Blumenbach

Answer 1

• Classified humans into 5 races

- “White, yellow, red, black, brown”

Question 2

The Concept of Race

Answer 2

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

Question 3

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

Answer 3

• Look at its enormous sociocultural significance

- Look at why it doesn’t hold up biologically

Question 4

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

Answer 4

• 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

Question 5

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

Answer 5

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

Question 6

Human Polymorphisms

Answer 6

• 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

Question 7

Alberta Sexual Sterilization

Answer 7

• 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

Question 8

Considerations about Race:

Human Populations are Heterogeneous

Answer 8

• 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

Question 9

Considerations about Race:

Polygenic traits are difficult to measure accurately

Answer 9

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

Question 10

Considerations about Race:

Discrete Boundaries

Answer 10

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

Question 11

Considerations about Race:

Traits are not linked

Answer 11

• 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

Question 12

Considerations about Race:

Specific # of traits cannot define a race

Answer 12

• 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

Question 13

Considerations about Race:

Genetic Diversity

Answer 13

• How much genetic diversity actually matters?

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

Question 14

Considerations about Race:

Gene flow

Answer 14

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

Question 15

Cline

Answer 15

• 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

Question 16

Solar Radiation:

Darker Skin

Answer 16

• 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)

Question 17

Solar Radiation:

Lighter Skin

Answer 17

• 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

Question 18

Lactose Tolerance

Answer 18

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

Question 19

Lactose Tolerance:

African vs. European

Answer 19

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

Question 20

Thermal Environment

Answer 20

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

Question 21

Acclimatizations

Answer 21

• 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

Question 22

Human’s Response to Heat

Answer 22

• 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

Question 23

Human’s Response to heat:

Vasodilation

Answer 23

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

Question 24

Bergmann’s Rule

Answer 24

“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

Question 25

Allen's Rule

Answer 25

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

Question 26

Human's Response to Cold: | Short Term

Answer 26

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

Question 27

Human's Response to Cold: | Long Term

Answer 27

- Seen mainly in groups acclimated to living in cold environment - Maintain high metabolic rate

Question 28

Human's Response to Cold: | Vasoconstriction

Answer 28

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

Question 29

High Altitude: | Factors (5)

Answer 29

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

Question 30

High Altitude: | Growth& development

Answer 30

* Larger heart size * Greater lung capacity * More efficient diffusion of oxygen to body tissues

Question 31

High Altitude: | The Indigenous Peoples of Tibet

Answer 31

* 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)

Question 32

Infectious Disease: | Causes- Biological& sociocultural (6)

Answer 32

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

Question 33

HIV/AIDS: | Stats and dates

Answer 33

- 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)

Question 34

HIV/AIDS: | Origin

Answer 34

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

Question 35

HIV/AIDS: | Genetics

Answer 35

- 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)??

Question 36

Smallpox

Answer 36

- 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

Question 37

Impact of Infectious Disease: | & Antibiotic Resistance

Answer 37

- #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