Anthropology Chapter 5: Evolution
- Science: a theory is based upon a hypothesis and backed by evidence
o A fact-based framework for describing a phenomenon
- Based on corroborated hypotheses
- Structures that explain and interpret facts
What Causes Gene Frequencies to Change?
- Population movement (migration)
- Random mating (genetic drift)
- Natural selection
- Gene frequencies change in every generation, evolution occurs continuously
Theory of Evolution by Natural Selection
1. More individuals than can survive
2. Variation exists
3. Limited resources
4. Adaptation to environment leads to differences in reproductive success
5. Change in gene frequencies
6. Accumulated change
For Natural Selection to Occur, Traits Must be:
- Heritable – cannot be acquired (eg. Giraffe’s neck)
- Variable – variation must exist in population
- How does the environment affect the organism?
- How does the organism affect the environment?
- How does the organism affect other organisms?
Ecology and Evolution
- Natural selection
o Individuals with features that are best suited to their environment are more likely to pass on their
genes in the greatest number
- Crucial factor in evolutionary process is an ecological factor
o The fit between organisms and their environment
Human Ecological Context
- The structure of the ecological system puts limits on the way of life of any living population
o What is the population’s relationship to its particular ecosystem?
o How are certain behaviours related to its relationship to that ecosystem?
Humans are unusual in our ecosystem
- Occupy virtually all ecosystems
o Habitats (area where we live)
o Niches (way of living)
o Humans dominate ecosystem
o Development of tools
Reliance of tools
- Use of technology allows us to have very different lifestyles
o Similar to speciation and niche formation in other animals
- Our ecosystems are less resilient than others
- Human populations are socially differentiated o More so than other social animals
Ecosystems and Adaptation
- Deeply enmeshed in our ecosystem
- Humans are unique in how quickly we respond through learning
- Different human societies can develop wholly different ways of life as they adjust to their environment
o Can change rapidly as circumstances r