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Evolution and Human Survival Lecture 4 PSY391S John Yeomans Diversity of Life Forms Categorization by phenotypes. Linneaus: Species, genus, family, order class, phylum, kingdom. Which features are most important in making groups? Can the same principles be used to make other groups?

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evolution and human survival

Evolution and Human Survival

Lecture 4

PSY391S

John Yeomans

diversity of life forms
Diversity of Life Forms
  • Categorization by phenotypes.
  • Linneaus: Species, genus, family, order class, phylum, kingdom.
  • Which features are most important in making groups?
  • Can the same principles be used to make other groups?
  • How were these groups formed?
diversity of ancient life
Diversity of Ancient Life
  • Geology: Older fossil forms in deeper sediments.
  • Changes in size, structure and design imply family histories. Evolution.
  • Variety of habitats and fossils. Beagle.
  • How did species evolve over millions of years?
  • Darwin: “Survival of Fittest”
evidence for theory
Evidence for Theory
  • Historical Record: Wars, famines, diseases, habitat lossselection.
  • Movement of species to new habitats new structures, e.g. lungs, legs, hair.
  • How did this happen in prehistory?
  • Selective breeding of domestic animals--pigeons, cows, dogs.
speciation
Speciation
  • Finches in Galapagos--Darwin and Grants.
  • When do phenotype differences become species differences?
  • How did humans diverge from primates?
  • Why did Neanderthals or other primates die?
how to survive
How to Survive?
  • “We are the accumulation of mechanisms that allowed our ancestors to survive and to reproduce their genes” (Sagan)
  • “Accumulation” includes functional and vestigial systems. DNA also an accumulation.
  • Who were our ancestors who managed to survive and reproduce?
  • The Selfish Gene: All our systems and strategies are shells for helping our genes survive.
  • Biological Purpose of Life?
human strategies
Human Strategies
  • Survival: Kill others genes and save your own? Humans survive by social cooperation rather than “dog eat dog”.
  • Reproduction: Have the most offspring possible? Humans have the fewest--single births, long immature period--but highest survival rate.
  • Learning and specialization--Civilization.
  • Aggression? Yes, but not to disrupt social organization.
classification and gene lineages

Classification and Gene Lineages

Lecture 5

PSY391S

John Yeomans

classification by phenotype
Classification by Phenotype
  • Which features are most important? Little agreement.
  • Principles of comparing different groups?
  • Where is change from species to genus to family etc, if evolution is continuous?
  • Genes are more fundamental, in theory, than any surface features.
  • Quantitative rather than qualitative.
classification by genes
Classification by Genes
  • Hybridization of DNA samples (Wilson).
  • Complete sequences, genomes.
  • Similarities in genes from flies to humans imply common lineages.
  • Reconstruction of family trees: Are all bases equally important?
  • Is DNA mutation rate constant?
  • Genetic Clock~ 1%/5 million years.
human family history
Human Family History
  • Females: Mitochondrial DNA is preserved from mother to daughter. 16,569 bases.
  • Trace human origins to Eve? Neanderthals?
  • Males: Y chromosome is preserved from father to son. Trace family lineage.
  • Trace DNA in all humans to extract lineages around the globe.
human genes
Human Genes
  • Which DNA makes us different from primates? E.g. prodynorphin.
  • Are some genes more important?
  • Which genes affect hands, brain, speech?
  • Could a few genes lead to larger brains?
cns evolution invertebrates
CNS Evolution--Invertebrates
  • Nerve nets: Action potentials, reflexes.
  • Ganglia chains: Molluscs, worms, arthropods.
  • Giant neurons and axons--no myelin.
  • Head ganglia are fused.
lecture 6 evolution of brain
Lecture 6: Evolution of Brain
  • Mammalian brain properties
  • Brain size vs. body weight
  • Ancient brains--when did they get bigger?
  • Human brains--when did they get bigger?
vertebrate cns
Vertebrate CNS
  • Protected brain and spinal cord.
  • Myelinated axons saves space for more neurons.
  • Shift from midbrain, cerebellum and olfaction to limbic system then cerebral cortex.
equation
Equation
  • Log Brain Weight=0.7(log Body Weight)+b
  • Or: Brain Weight = K(Body Wt)0.7
  • Power function linear on log-log plot.
  • Some mammals have extra brain size (Humans and dolphins 8X extra)
  • K = encephalization factor.
ancient vertebrates
Ancient Vertebrates
  • Brain weight from endocranial space.
  • Body weight from leg bone diameter.
  • Ancient reptiles same as modern reptiles, except for Archeopteryx (bird-like predator).
  • Modern birds and mammals increased brain capacity by 4X over ancient birds and mammals (still 4X reptiles).
  • Warm blood favors brain evolution?
evolution of human brain
Evolution of Human Brain
  • Increased by 3X about 1-2 million years ago.
  • Most of change in frontal cortex.
  • Neoteny: Do we sustain embryonic brain growth for longer by keeping neonate features?
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