Patterns of Variation

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As you work through this set of chapter slides, keep in mind the notations that are included from your instructor. Open, read carefully, download if necessary, and use in conjunction with your reading and video lesson study. All these components supplement each other. The wise student will keep this in mind.

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Think about it. Humans obviously differ one from the other, but also from group to group, from population to population. How do we account for this variation without falling into the trap of “racism” and the pitfalls of the past?

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POPULATION... see p.105 and know how we need to understand this term and the associated concepts listed here. In this connection, study the following terms:

Deme is a local interbreeding population defined in terms of its genetic composition.

Example: Eastern Caroline Islands 1775100,00010,000

Subspecies are local populations that share part of the geographic range of the species and can be distinguished because of one or more phenotypic traits.

Race “can” be viewed in terms of a subspecies

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In addition to the ideas in this slide, consider the following:

The Dark Ages: Attila the Hun (d.453), King of the Barbarians. From the 5th century onward, knowledge of other places & people waned as libraries were looted.

The Renaissance: Broadening of historians’ perspectives on people over the ages arises, ironically, due to rediscovery of classical literature of the Greeks & Romans.

The Age of Discovery: In 1492 Columbus gets lost and “discovers” people and places that intrigued him & others.

Pope Paul III finds it necessary in 1537 to publish a church document proclaiming that American Indians are humans and must be included in the one act of divine creation (monogenism).

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* Linnaeus (1707-1778); A monogenist, he divided Homo sapiens into subspecies as follow:

H.S. Afer (African/black)

H.s. Americanus (American Indian/red)

H.s. Asiaticus (darkish)

H.s. Europaeus (white)

This system did not stand up among later scientists.

Other monogenism proponents were Blumenbach (1752-1840) who described five races: Caucasian, Mongolian, Ethiopian, American, and Malayan.

Environmentalism: The human body is “plastic” and environment can shape anatomy! Rev. Samuel Smith 1751-1819

Polygenism: Enter Samuel George Morton, a Quaker, who saw this perspective almost as a compromise. Due to repeated acts of creation by God, a variety of races exist.

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RACE & RACISM: Consider Germany, Japan, and the United States

Germany: Ayrianism, Nazis, Neo-Nazis

Japan: Pre-WW II ideas on divinity of Emperor promoted a sense of Japanese superiority and fed into the war.

United States: Slavery, Jim Crowe, Internment camps, etc., punctuate history here. Even now, see how the Aryan Brotherhood continues to exist.

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A big name to read up on here is Franz Boas, the father of modern anthropology emphasizes field work and participant observation.

In addition, there was Ashley Montague (1905-1999), who argued tirelessly against the use of the term “race” in science. Note well that in the realm of the biological sciences the term has no scientific validity.

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Skin color: Natural selection feeds on geographic origin as to skin tone. Darker skin offers a selective advantage for populations living near the Equator, while light skin does this for folks in Northern hemisphere locations.

Eye form: The epicanthic fold offers a selective advantage and is the technical term for what is sometimes referred to as “Asian” eyes. (see p.111)

Hair color & form: melanin, skin color/hair color! There is usually a good reason for these. Check our textbook!

Head shape: *Cephalic index was proposed by Retzius (1796-1860. Misused, this index led to racism by some.

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Read up on these and have a general sense of what is meant here.

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Again, have a general sense of is meant by the first two terms listed here.

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Same idea again!

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Read p. 114 for examples of this phenomenon.

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Read p. 116 for examples of this phenomenon.

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See p. 118 for this.

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Consult pp. 120-21 on this.

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a. LEVELS OF ADAPTABILITY (aka ADJUSTMENTS) See p. 124ff

Acclimatization: Short-term adjustments in the body occurring in response to environmental changes. (p.125)

Other Acclimatory Adjustments would involve changes in blood chemistry at high altitudes.

High altitude hypoxia: the need to breathe more rapidly so as to grab oxygen.

Behavioral adjustments include changes in clothing (swim suit vs. fur coat!).

Physiological changes include (under desert conditions) our experience of Vasodilation = capillaries of the skin dilate.

On the other hand, under extreme cold conditions we experience Vasoconstriction = capillaries constrict! [note how your watch band slips loosely on your wrist in winter.

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Again, see p. 124 on this.

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See pp. 124-26 for these first two issues:

Vasodilation = capillaries of the skin dilate.

Vasoconstriction = capillaries constrict.

Several principles have been proposed to describe the relationships between surface area of body & mass of the body in mammals, including humans. These rules were generated by Allen (1838-1921 & Bergman (1814-1865).

Allen`s rule (p.126) states that populations [of the same species] living near the equator tend to be taller & to have longer limbs when compared to populations farther away from the equator (short bulky body & small nose in frigid areas).

Bergmann`s rule states that while tall populations with less bulk are found near the equator (Masai), those with greater bulk & generally shorter stature (Eskimo/Inuit) are found farther from the equator.

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HIGH ALTITUDE LIVING (p.128): Scientists notice differences in patterns of growth and development in children growing up in stressful environments.

SKIN COLOR (p. 129): Human skin color is due primarily to the pigment melanin. Melanin is produced in specialized cells, which represent 5% of the cells in the epidermis (p.130)...these are melanocytes.

Skin color is determined by:

1. Amount of melanin produced; 2. size of melanin particles;

3. Rate of melanin production; 4. location of melanin in the skin.

Skin color is also affected by HEMOGLOBIN

Advantages/Disadvantages of a particular skin color: Melanin serves to protect the darker body from the harmful ultraviolet rays of the sun and also regulates production of vitamin D.

* Skin Color as an Adaptation: So, skin color may be the result of selective agents--e.g., the sun’s rays--acting on a population.