2. Supplements
The following students supplements are available with the textbook:
The Kottak Anthropology Atlas, available shrink-wrapped with the text, offers 26 anthropology related reference maps.
The Student's Online Learning Center features a large number of helpful study tools and self quizzes, interactive exercises and activities, links, readings and useful information at
PowerWeb, available via a link on the Student's Online Learning Center, offers help with online research by providing access to high quality academic sources."

3. Evolution and Genetics
This chapter introduces students to the process and mechanisms of biological evolution. It begins with a discussion of Mendelian genetics and then it discusses the mechanisms of genetic evolution. It concludes with case studies about human biological adaptation.
Evolution and Genetics

4. Creationism and Catastrophism
Creationism accounts for biological diversity by referring to the divine act of Creation as described in Genesis.
The discovery of fossil remains of creatures clearly unknown to modern humans was not accountable within the terms of simple Creationism.
Catastrophism is a modified version of Creationism, which accounts for the fossil record by positing divinely authored worldwide disasters that wiped out the creatures represented in the fossil record, who were then supplanted by newer, created species.
Both versions of creationism describe the different species of plants and animals as essentially different, having distinct, separate moments of creation.

5. Evolution
An alternative term for early evolutionism was “transformism.”
Darwin was influenced by the geological concept of uniformitarianism.
Uniformitarianism states that past geological events can be best explained by observing the ongoing events of the present and generalizing backward through time.
It further asserts that current geological structures are the result of long-term natural forces.
Transformism had posited the primordial relatedness of all life forms.

6. Natural Selection
Darwin posited natural selection as the mechanism through which speciation takes shape (reaching this conclusion along with Alfred Russell Wallace).
Natural selection is the gradual process by which nature selects the forms most fit to survive and reproduce in a given environment.
For natural selection to work on a given population, there must be variety within that population and competition for strategic resources.
The concept of natural selection argues that organisms which have a better fit within their environmental niche will reproduce more frequently than those organisms that fit less well.

7. Genetics
The science of genetics explains the origin of the variety upon which natural selection operates.
Heredity Is Particulate

8. Gregor Mendel
The study of hereditary traits was begun in 1856 by Gregor Mendel, an Austrian monk.
By experimenting with successive generations of pea plants, Mendel came to the conclusion that heredity is determined by discrete particles, the effects of which may disappear in one generation and reappear in the next.
Mendel determined that the traits he observed occurred in two basic forms: dominant and recessive.
Dominant forms manifest themselves in each generation.
Recessive forms are masked whenever they are paired with a dominant form of the same trait in a hybrid individual.
It has since been demonstrated that some traits have more than these two forms--human blood type, for example, has several forms, some of which are codominant.

9. Mendel’s Observations
Humans have twenty-three matched pairs of chromosomes, with each parent contributing one chromosome to each pair.
Chromosomes contain several genes, or genetic loci, which determine the nature of a particular trait.
A trait may be determined by more than one gene.
Alleles are the biochemically different forms which may occur at any given genetic locus.
Chromosome pairs’ loci may be homozygous (identical alleles) or heterozygous (mixed).

10. Independent Assortment and Recombination
Mendel also determined that traits are inherited independently of one another.
The fact that traits are transmitted independently of one another, and hence may occur in new combinations with other traits, is responsible for much of the variety upon which natural selection operates.
Mitosis is ordinary cell division, wherein one cell splits to form two identical cells.
Meiosis is the type of division particular to sex cells, wherein four cells are produced from one, each with half the genetic material of the original cell (i.e., twenty-three chromosomes instead of forty-six).
Fertilization allows the products of meiosis from one parent to recombine with those from the other parent.
Because genes sort independently during recombination, the number of possible combinations is exponentially high (223): a major source of variety.

11. Population Genetics
Population genetics looks at changes in gene frequencies at the level of the community or breeding population
Gene pool refers to all of the alleles and genotypes within a breeding population.
Genetic evolution is defined as change in the frequency of alleles in breeding population from generation to generation.
There are four basic mechanisms which produce changes in gene frequency in a population: natural selection, mutation, genetic drift, and gene flow.

12. Natural Selection
Genotype refers to the genetic makeup of an organism.
Phenotype is the expression of the genotype as it has been influenced through development by interacting with its environment.
Environmental influence in this interaction is extremely important, and lends great plasticity to human biology.
Natural selection acts upon phenotypes.

13. Directional Selection
Natural selection affects gene frequencies within a population.
Adaptive genes are selected for (organisms containing them reproduce more frequently).
Maladaptive genes are selected against (organisms containing them reproduce less frequently).
When specific adaptive genes are selected for over a long time period, causing a major shift in gene frequency, this is called directional selection.
Directional selection continues until equilibrium is reached (due to the effects of contradictory selective forces, the base mutation rate, or both).
Directional selection, in favoring one gene, can reduce variation in a gene pool.

14. Sickle-Cell Anemia
Just as directional selection can reduce variety, it can also maintain genetic variety by favoring a situation in which the frequency of certain alleles remains constant between generations.
Hemoglobin in Africa
HbA and HbS are two alleles for a gene which largely determines hemoglobin production in humans.
Homozygous HbA produces normal hemoglobin; homozygous HbS produces lethal sickle-cell anemia; heterozygosity for this gene produces the (in some circumstances) deleterious but nonlethal sickle-cell syndrome.

15. Sickle-Cell Anemia (cont.)
It was discovered in certain populations in Africa, India, and the Mediterranean that HbS existed at surprisingly high frequencies.
This is largely explained by the fact that the populations noted were in heavily malarial areas, and that the heterozygous form produced a phenotype that was resistant to malaria, and was thus the phenotype most fit for that environment.
It is important to note that traits that are maladaptive in one environment, such as the sickle cell would be in a malaria-free zone, can be adaptive in a different environment, and the reverse of this is also true.

16. Mutation
Mutation introduces genetic variation into a breeding population.
Chemical alterations in genes may provide a population with entirely new phenotypes, with possible concomitant selective advantages.
The spread of HbS in heavily malarial environments is one example.

17. Random Genetic Drift
Random genetic drift is the loss of alleles from a population's gene pool through chance.
There is no set form for this chance; it may simply occur through a statistical fluke in sexual reproduction patterns, or through the effects of a catastrophe on the population as a whole.

18. Gene Flow
Gene flow occurs through interbreeding: the transmission of genetic material from one population to another.
Gene flow inhibits speciation, the formation of new species.
A species is an internally interbreeding population whose offspring can survive and are capable of reproduction.
Speciation occurs when populations of the same species become isolated from each other (thus stopping gene flow) allowing natural selection and genetic drift gradually to produce gene pools that are different, to the extent that successful interbreeding is no longer impossible.

19. Human Biological Adaptation
Much of the human biological diversity is the result of human genetic adaptation to specific environments.
The high frequencies of the HbS heterozygote in malarial environments are a good example.
Some alleles that were once maladaptive can lose their disadvantage if the environment changes.
The Human Genome Project is working to map all of the genes and chromosomes found in humans.
Many of today’s incurable hereditary diseases someday may be rendered evolutionarily neutral through genetic therapies.
One downside of this research is that it can also lead to genetic discrimination (eugenics).

20. Genes and Disease
Despite the advances in medical research over the last 100 years, diseases still pose a significant threat to the health of human populations all over the world.
Human blood factors play an important role in resistance to some diseases.
There is evidence that the various alleles producing human blood types interact with infectious and noninfectious ailments.
For example, the presence of type A blood cells seems to make a person more susceptible to smallpox.

21. Facial Features
Thomson's nose rule asserts that noses tend to be longer in colder climates.
The Australian Aborigines' sand-permeated diet has selected for larger teeth than seen in other populations.

22. Size and Body Build
Different climates have selected for different body shapes.
Bergmann's rule: because of the respective ratios between mass and surface area, smaller bodies dissipate heat faster, and larger bodies retain heat better; thus more larger animals are found in colder habitats, while smaller animals have been selected for in hotter habitats.
Allen's Rule: slender bodies with long limbs dissipate heat more efficiently and are selected for in tropical climates; heavy, short-limbed bodies retain heat better and are selected for in colder climates.

23. Lactose Intolerance
The term phenotypic adaptation refers to changes which occur to an individual organism during it's lifetime which enhance its reproductive fitness.
Individuals from herding populations in northern Europe and parts of Africa maintain their ability to digest milk (continue to produce the enzyme, lactase) into adulthood, whereas people from other populations can digest milk (specifically, milk sugar, called lactose) only during childhood.
The fact that descendents of these herding population who no longer herd continue to be lactose tolerant as adults indicates genetic adaptation to a milk-rich diet.
The fact that lactose intolerance can vary during an individual's adult life, depending on how much milk is consumed, indicates that some phenotypic adaptation also takes place.