Week 2 Ch 2

4 Pages
Unlock Document

Cognitive Sciences
Thomas Michael D' Zmura

Chapter 2: The Genetic and Evolutionary Roots of Behavior Genetics and DNA • Chromosomes- structures in the nucleus of each cell that contain the genes, the units of hereditary transmission; human cell has 46 chromosomes arranged in 23 pairs • DNA- the complex molecule that is the constituent of genes Genes • DNA molecule forms double helix; subunits are adenine, thymine, cytosine, guanine • Base pairs allow DNA to carry instructions for proteins • Gene- a section of a DNA molecule that contains instructions for how and when to assemble a protein. Genes are located on chromosomes. Gene Expression • Environment outside the cell can affect whether a gene will be expressed • Timing: some genes active early in organism’s development but not later • Organism’s overall environment and its behavior  temperature, stimulation, interactions • Genotype- complete set of an organism’s genes  defined by the specific sequence of genes on each of its chromosomes • Phenotype- overt characteristics and behaviors of an organism  defined by what the organism is actually like o Product of both genotype and the environment Gene Transmission • Matter of chance which of the father’s/mother’s chromosomes go into each egg Interactions among Genes • Gregor Mendel and pea plants • Allele- an alternative form of a specific gene • Dimples are dominant- term for a gene that directs the development of a certain characteristic even when the corresponding gene on the other chromosome is different – i.e., some other allele o Recessive- a term for a gene that directs the development of a particular characteristic only if the corresponding gene on the other chromosome matches it – i.e., is the same allele • Genotype may not always lead to phenotype o Ex. PKU depends on diet, not just recessive alleles of that particular gene o Codominance- both genes in the pair affect the phenotype  Ex. Blood type o Incomplete dominance- person with two different alleles with have a phenotype that’s intermediate between the types favored by each allele on its own  Ex. Serotonin transporter gene Polygenic Inheritance • Polygenic inheritance- a pattern in which many genes all influence a single trait Evolution By Natural Selection • Proximate causes- the influences within an organism’s lifetime that led to its particular traits or behaviors • Ultimate cause- the reasons why, over many years of evolution, a particular trait or behavior helped members of a population to survive and reproduce The Principles of Natural Selection • Natural selection- the mechanism that drives biological evolution; it refers to the greater likelihood of successful reproduction for organisms whose attributes are advantageous in a given environment • Naturalistic fallacy- the (mistaken) idea that anything “natural” must be “good” Genes and Evolution • Darwin’s 3 important principles: o 1. Must be variation among individuals within a population o 2. Certain of the variants must survive and reproduce at higher rates than others o 3. Traits associated with this superior survival and reproduction must be passed from parents to offspring • How variety occurs o Mutations- errors in the replication of DNA Evidence for Evolution by Natural Selection • Three spine stickleback • Vestigial structures The Unity of Life • All of Earth’s living things are derived from a common lineage • Jellyfish with green fluorescent protein  inserted into monkeys, makes monkeys green The Genetics and Evolution of Behavior • Psychological traits are a part of an animal’s phenotype o If the phenotype will make the animal more likely to survive/reproduce, the animal’s genes will be well represented in the next generation • Evolution has favored mechanisms that produce flexibility in how an animal acts o Need for flexibility is amplified by the process of niche construction- the process in which organisms, through their own behaviors, alter the environment and create their own circumstances The Biological Roots of Smiling • Sometimes, style of communications is species specific- pertaining to just one species • The Origins of Smiling o The behavior of smiling is species general- pertaining to all organisms in a species o Smiling was the most accurate identification in an experiment with Americans and New Guinea tribesmen in describing each other’s emotions • Smiles in Other Species o Darwin’s The Expression of the Emotions in Man and Animals o Expressive smile  produced even if no one around, change in mouth’s shape, formation of crow’s feet- lines that radiate outward from the eyes o Pol
More Less

Related notes for PSYCH 9A

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.