Intro to Evolutionary Anthropology
January 14
- Evolutionary Anthropology: Application of modern evolutionary theory to studies of morphology, ecology, and behaviour of human and non-human primates
- Primatology: Study of non-human primates
- Paleoanthropology: Study of biological evolution of humans and non-human primates, advent of and changes in human cultural activities, evolutionary of behaviour in humans and non-human primates
- *Evolution is not about making things better
- Human Variation: Spatial and temporal variations in human features (such as climatic/geographic variations)
- Medical Anthropology: How various factors influence health and illness of individuals at small and large levels
- Forensic Anthropology: Focus on human skeletal remains, seek to determine features of the deceased
Scientific Method:
| S | State the problem |
|---|---|
| G | Gather information |
| F | Form a hypothesis |
| T | Test the hypothesis |
| R | Record and analyze data |
| S | State the conclusion |
| R | Repeat the work |
- Multiple scientists do same work, to avoid bias
Evolutionary Theory
Problems that Limited Evolutionary Theory:
Lack of knowledge of age of Earth
Religious concept of fixity of species
Lack of scientific method
Religious notion of separate creation for humans and animals
- According to Bishop Usher, Earth was created on October 23, 4004 BC (2:30 pm)
- Fixity of species: All species are unchanging and distinct, as created by God
- Many ideas and concepts based on verbal accounts of travellers, which were often inaccurate
- Belief that humans are divine, and above non-human animals
Development of Evolution Theory
- Carolus Linneaus (1707-1778): Father of Taxonomy; grouped species by genus, based on physical resemblances; believed he was classifying God’s creations; Scala Naturae, leading up to humans on top; others continued his work after his death
- Binomial Nomenclature (system): First letter of genus capitalized, species designation lowercase [ex. Homo sapiens]
- Georges-Louis Leclerc (1707-1788): Believed Earth was 75 000 years old; wrote book about it which was criticized by the church; founded biogeography (different regions with similar climates have distinct plants and animals)
- Jean-Baptiste Lamarck (1744-1829)
- Inheritance of Acquired Characteristics: creatures have “vital traits” that help them adapt to environments, which are passed on to future generations; this theory does not support idea that giraffes willed their necks to grow longer
- Charles Darwin (1809-1882):
- First concluded that Earth must have an ancient history, no fixity of species (kept ideas private)
- Variation leads to advantages for certain individuals, meaning higher reproduction, and said variation becomes the norm
- Thomas Malthus (1766-1834): Essay on the Principle of Population (1798): more organisms are born than can possibly survive; individuals adapt to environments, which leads to evolutionary shift over time (Darwin)
Darwin’s Theory on Natural Selection:
All species (extant and extinct) share a common ancestor; species evolve by natural selection
- Alfred Russell Wallace (1823-1913): Writes to Darwin, describing ideals similar to those Darwin has kept hidden for years, less evidence but similar core ideas; joint presentation of ideas proposed
- Darwin published On the Origin of Species by Means of Natural Selection or The Preservation of Favoured Races in the Struggle for Life
- The word “evolution” does NOT appear in the first edition of Origins of SpeciesDarwin avoided implications of general progress or directionality; his later works apply evolution to humans
Natural Selection
- A process in nature resulting in survival and perpetuation of only those forms of life having certain favourable characteristics that enable them to adapt best to their environment.
Three postulates of Darwinian Evolution:
- Struggle for existence: ability of population to expand is infinite, but their environment is finite
- Variation in fitness: Organisms vary, some individuals possess traits enabling them to survive and reproduce more successfully than others in the same environment
- Inheritance of variation: Advantageous traits inherited by offspring become more common in succeeding generations. Traits that confer advantages in survival and reproduction retained in population; disadvantageous traits disappear.
Sexual selection
- Certain evolutionary traits can be explained by ==intraspecific (within-species) competition==
- [Male birds are much more brightly coloured than females, to better attract a mate)
- Elaborate animal mating rituals, competition among males for female access
- Evolution does not always result in general increase of fitness
- Environment constantly changing (usually for the worse); Red Queen analogy (must keep running to survive); design limitations in biology
“Survival of the Fittest”:
- Coined by Herbert Spencer, NOT Darwin
- Proclaimed wrongly that human struggles for existence leads to beneficiary evolution; argued against policies that might interfere with this progress, like charity
- Major weakness of Darwinian Evolution: No explanation on how characteristics inherited; Darwin could never prove it
Inheritance
- Gregor Mendel (1822-1884): Pea plant experiment; chose pea plants for several reasons:
- Inbred: true-breeding lines
- Hybrids: quantify traits
- Observable traits: flower colour, seed colour, etc.
- Plants small: easy to grow in large numbers, short generation time for several crosses per growing season
- Self-fertilizing: but can cross fertilize
- Mendel cross-pollinated green and yellow plants (all yellow seeds produced), then self-pollinated yellow plants, and found 3:1 ratio of yellow to green seeds (green seeds are dormant trait)\
- Concluded each plant carries 2 copies of “factor” which determines a trait; published findings gathered little interest for over 100 years
- No understanding of genetics at the time, Mendel could not explain his findings
- Mendelian Traits in Humans: cleft chin (dominant), cheek dimples (dominant), free (dominant) or attached (recessive) earlobes, wet (dominant) or dry (recessive) earwax
- Non-Mendelian Traits: eye colour, hair colour, Morton’s Toe, tongue rolling, wisdom, athletic ability