Upload
margery-sparks
View
224
Download
0
Tags:
Embed Size (px)
Citation preview
Chapter 3
Evolution and Genetics
Where did we come from?
Human history is relatively short
Evolutionary history is extremely long
Species
A species is a reproductively isolated breeding population More than 95% of all species that have ever
lived are now extinct
Distal and Proximal Causes of Behavior
Distal (ultimate) causes: causes of behavior rooted in evolutionary and genetic
determinants
Proximal (nearby) causes: Causes of behavior that focus on immediate, local,
(psychological and sociological) determinants. Crying behavior shows both distal and proximal causes:
Darwin’s Theory of Evolution
On the Origin of Species by Means of Natural Selection (1859)
Evolution: existing species of life on earth are the end
result of a process of natural selection
Adaptation
Any characteristic that improves the "fit" of a plant or animal with its environment, thereby increasing its chances of transmitting genes to the next generation.
Natural Selection
The means by which organisms adapt to the environment and reproduce differentially.
Selective Pressure Any feature of an environment that allows one
organism to have reproductive advantage over another.
Lamarckian Evolution
The theory that genetic changes can occur in populations through the inheritance of characteristics acquired during a lifetime.
Cataclysmic Disasters
Mass extinction due to natural calamities E.g. asteroid impact resulted in sudden
extinction of the dinosaurs
Genetics and Heredity
Genes The basic units of heredity
Genotype The genetic constitution of an individual
organism
Phenotype The physical expression of features in an
organism that results from the interaction of its genotype with the environment
Mendel’s Experiments:
Breeding peas with dominant and recessive traits results in predictable proportions of offspring
Aa bred with Aa results in 75% dominant phenotype, 25% recessive phenotype
Mendel’s Experiments
Aa Aa
Aa AaAA aa
Note: These three offspring appear identical.
Deoxyribonucleic Acid (DNA)
A double-strand, helix-shaped structure containing genetic material. The basis of the chromosome:
A structure in the nucleus of a cell that carries genetic information
Genetic Relatedness
Degree of Relatedness Individual Organism Percentage of genesshared with you
an identical twin 100%
first degree a sibling (brother or sister) 50a mother or father 50a child 50
second degree a grandparent 25a grandchild 25a half-brother or half-sister 25an aunt or uncle 25a niece or nephew 25
third degree a first cousin 12.5
a stepchild 0 or ?a spouse 0 or ?
Genetic Relatedness
Homo Sapiens has a shared genetic history with all its ancestors
We also have a shared genetic relationship with other animals Up to 98.4% genetic
similarity to some chimpanzee species
Genetic Variability
Meiosis The process of cell division
that produces sex cells (sperm and egg) containing one of each pair of chromosomes
“Crossing over” results in genetic variability
How can genes influence behavior?
Genes can only produce proteins Proteins create structures like the brain
Genes and Environment
Phylogenetic History The evolutionary history of a specific group of
organisms
Ontogenetic History The history of an animal’s entire development, from
fertilization through death
Extragenetic History Information in the form of cultural wisdom, including
oral and written history, that is passed across generations
Nature vs. Nurture
Species-specific behaviors adaptive, innate response
patterns typical of a species
Learning Changes in behavior
resulting from experience
Behavioral Genetics
The study of how genes, interacting with environments, affect behavior
E.g. Emotionality in dogs Breeding fearful basenji dogs with sociable
cocker spaniels results in an F2 pattern of offspring similar to that seen in Mendel’s experiments3/4 Fearful, 1/4 sociable
Fearfulness is a dominant trait
Behavioral Genetics
Obesity in mice
Behavioral Genetics
Obesity in mice Inbreeding heavy mice results in heavier
offspring
An example of a polygenic character A character that varies in a continuous
manner, presumably caused by the effects of many genes
Ethology
The study of species-specific behaviors
Ethologists are interested in instinctive behaviors Patterns of behaviors that are common to a
species
Ethology
Appetitive Behaviors Preliminary activities that precede and lead to
consummatory behaviors
Consummatory Behaviors Innate "survival" behaviors such as copulating
and eating
Imprinting
A highly adaptive innate behavioral process that involves the rapid development of a response to a specific stimulus at a particular stage of development E.g. following behavior in
goslings
Fixed Action Patterns
Programmed sequence of species-specific behaviors that are triggered by a particular stimuli E.g. egg-retrieval in
geese
Fixed Action Patterns
Sign Stimulus A specific environmental stimulus that triggers
innately organized behaviorsE.g. sight of egg
Innate Releasing Mechanism A neural mechanism that triggers an innately
organized motor program
Species-Specific Defense Reaction
An innately organized hierarchy of defense behaviors elicited by signals indicating potential danger E.g. “freezing” and fleeing from danger in rats
Comparative Psychology
The study of the motivation and behavior of animals in order to identify similarities and differences among them
Morgan’s Canon: One should not attribute complex
psychological processes to non-human animals if a simpler explanation is available
Anthropomorphism
The attribution of human characteristics to animals
Zoomorphism
The attribution of animal qualities to humans
Contact Comfort
Harlows Baby monkeys prefer contact with soft
“mother” over “mother” that merely gives food
Harlow picture
Pair Bonding
A strong and enduring affection that unites an infant with a parent Social isolation disrupts pair bonding and
later adult interactions (Harlows)
Neuroethology
The study of the relationship between the nervous system and consummatory behaviors E.g. brain areas controlling song in birds
change in size as a function of hormone levels
Sociobiology
The study of the genetic determinants of social behavior
Evolutionary Psychology The study of human and animal minds and
behavior from the perspective of evolutionary theory.
The “Selfish Gene” - Dawkins
Human behavior can be viewed as an attempt by our genes to propagate themselves
Kin Selection The theory that one promotes the well-being and
inclusive fitness of a genetic relative because of shared genes
Inclusive Fitness The fitness of an individual and related individuals
(who carry many of the same genes)
Altruism
A behavior that helps another individual but may diminish one’s survival or reproductive potential The likelihood of altruism correlates with the
one’s genetic relationship to the individual receiving help
Mating Patterns
Monogamy
Polyandry
Polygyny
Polygandry
Mating Patterns
Parental Investment
Mating patterns are influenced by how much an offspring’s survival costs one parent or another E.g. carrying a child through gestation vs.
providing sperm E.g. time spent guarding mate or offspring
Human Mating Systems