Lecture 14- Genes and culture make us different Flashcards
What is nature and nurture?
- Nature behaviour is determined by genetics; environment has little influence
- Nurture behaviour is determined by learning from the environment and genetics has little influence
What is the Seville statement on violence?
The Seville Statement on Violence is a statement on violence that was adopted by an international meeting of scientists, convened by the Spanish National Commission for UNESCO, in Seville, Spain, on 16 May 1986. It was subsequently adopted by UNESCO at the twenty-fiHh session of the General Conference on 16 November 1989. The statement, then known as a ‘Statement on Violence’, was designed to refute “the no2on that organized human violence is biologically determined”
- It is scientifically incorrect to say that we have inherited a tendence to make war from our animal ancestors
- It is scientifically incorrect to say that war or any other violent behaviour is genetically programmed into our human nature
- It is scientifically incorrect to say that in the course of evolution there has been a selection for aggressive behaviour more than for any other kinds of behaviour
- It is scientifically incorrect to say that humans have a violent brain
- It is scientifically incorrect to say that war is caused by instinct or any single motivation
What to remember?
- the most important thing to remember is the influence of genes and culture, the evolution has to be in genes!
- sometimes the data is just interesting but doesn’t actually say anything about evolution!
What is the gender issue?
-notion that there are genetic differences between men and women
-we condition children into male/female roles from early age onwards
-experiments looking at small children, what toys they prefer
-the experimenter knew the sex of the offspring so not blind!
-really easy to be influenced by the culture so have to be really careful to say what is biologically given!
Some condiBons have a geneBc cause:
• cys>c fibrosis: caused by a recessive gene located on chromosome 7 Some condiBons have an environmental cause:
• the acquisi2on of a par2cular language depends upon what is spoken in the child’s environment
InteracBon:
• the outcome produced by a gene may depend upon the context in which the gene is expressed
What are cross-fostering experiments?
Cross-fostering experiments
• offspring are randomly split between biological and ‘foster’ parents and differences in trait expression reveal the influence of ‘gene2c’ and ‘environmental’ effects
• birds provide especially easy model species to inves2gate these effects, because eggs can be readily transferred
• but at what stage does environment not have an effect?
What is the maternal influence on mice behaviour?
• two strains of mice, B6 and BALB, differ in ‘boldness’
• B6 embryos transplanted to BALB uteri and raised by BALB mothers display, as adults, aspects of BALB behaviour
• cross-fostering, the transfer of an infant B6 to a BALB parent, does not provoke the change
• the uterine environment is necessary to elicit the change: B6 genotype expresses B6-typical behaviour only aHer development in a B6 uterus
-some bold and some not, seems uterine environment is important
What are adoption studies? (can use as cross fostering)
- Adop2on studies are based on a comparison of the concordance or correla2on between offspring behavior and the characteris2cs of both the biological and adop2ve parents
- cross-fostering studies in zoology – split offspring between biological and ‘foster’ parents and measure difference in trait expression
What are twin studies? (can use as cross fostering)
• Classical twin studies compare data from identical/ monozygotic (MZ) with fraternal/dizygotic (DZ) twin pairs, reared together
- looking at the predictive correlation of traits between twins
- with dizygotic twins 0.5 genetic (half genome shared) and 1.0 environmental
- monozygotic twins: 1.0 genetic and 1.0 environmental
What was the large survey targeting digust and emotion?
• Web-based survey, completed by 77,000 people, but exclusions yielded only
What is the issue with left handedness?
- left-handed people in the minority in all human populations
- several fitness costs allegedly associated with left-handedness • countervailing benefit must exist to maintain polymorphism
What are the genetic patterns of left-handedness?
- MZ twins – if first born is right handed, 4% of the second born is left handed, whereas if first born is left handed, then 12% of second born is left handed
- DZ twins – if first born is right handed, 5% of the second born is left handed, whereas if first born is left handed, then 9% of second born is left handed
What are the costs of being left handed?
- left handed people live shorter lives even today
- much higher incidence of accidents
- Right handed humans expect to live longer than left handed humans – sample of 987 random death records and handedness reports from next of kin
What are the possible benefits of of being left-handed?
• left-handed people in the minority in all human populations
• several fitness costs allegedly associated with left-handedness
• countervailing benefit must exist to maintain polymorphism
• left-handed people at advantage in sports involving dual confrontations
(fencing, tennis, baseball)
• left-handed people at advantage in aggressive interactions?
What is the relationship between homicide rates and the prevalence of left-handedness?
-the more left-handed people in the population the more homicides occur in that population (so it seems)
-possible explanation is that left-handed people are at an advantage in fights and are more successful in killing others
Some problems:
• is the cost of left-handedness substantial, and relevant to the societies in this study?
• is homicide rate the best estimate of prevalence of one-to-one fights?
• are there confounding variables that might be driving this correlation?
