week 6 - nature vs nurture - genes vs environment

Question 1

In the 1970s what were peoples beliefs on nature vs nurture?

Answer 1

many people thought the environment was everything and you could turn a person into anything you wanted them to be by changing the environment. One way people thought this was possible was by exposing boys and girls to the choice of toys by children as to turning them into boys and girls.

Question 2

In the late 80s/90s what were peoples beliefs on nature vs nurture?

Answer 2

The other end of the spectrum specifically in the late 80s or 90s when more genetic tools became available there was a view point that everything would be genetically determined. No environmental effect at all. People thought they had discovered a gay gene or a criminal gene. We know now that behaviour patterns are often determined by many rare genes or multiple genes.

Question 3

Experiment on the development of social behaviour in rhesus monkeys - now unethical

Answer 3

1950s with rhesus monkeys
in order to streamline the behaviour process he thought they had to isolate them from biological mothers
how this isolation would produce normally behaving rhesus monkeys
so one of the questions was is motherhood only a giver of food. So he experimented with various dummies that just provided milk.
turned out when given the choice the monkeys preferred the cloth rapped dummies rather than the wire cage and spent a long time hugging the cloth dummies and only went over to the wire cage for food.
the wire cage caused the monkeys to turn out normally in terms of morphology but their behaviour was abnormal and they were excessively aggressive or shy
just being with the biological mother giving milk this still resulted in abnormal social behaviour
just playing with other younger monkeys for 50minustes a day resulted in normal behaviour

so the conclusion was that only relatively minimum contact with conspecifics is needed for normal behaving rhesus monkeys. Prolonged isolation causes abnormal behaviour.

Question 4

Evidence for genes controlling behaviour in drosophila?

Answer 4

• historic study on movement behaviour
• 2 types of drosophila larvae
• monitor their tracks in a petri dish
• one type of larvae will cover relatively long bits of tracks
• whereas other individuals in the same period of time will only cover a small area.
• this is a behaviour routine that is clearly genetic. Some larvae are lazy others are not
• if you pair lazy and lazy together you get a movement distribution reflecting that.
• clearly see the rover distribution in the right graph
• if you cross sitter males with rover females you get an intermediate distribution. That is the middle graph.
• Interestingly in the F2 if you cross them again and measure the track length then you find the typical 3:1 distribution that you would find in any dominant recessive allele. This means that there is likely a single gene determining it, and the rover gene is dominant and the sitter gene recessive.

Question 5

genetic behaviour experiment evidence birds

Answer 5

many temperate birds migrate south in winter months. there are a variety of warblers which have specific routes depending on where they originate. The british and scandanavian warblers all fly over spain to Africa west.
when these birds first hatch they have no idea where to go, and one type of experiment you do is raise them separately from their parents and see where they want to go for migration.

put them in a funnel with some ink at the bottom. Tend to migrate at night. Filter paper around this arrangement. And measure where the birds inky feet mess up the filter. What you can do is measure the populations which migrate via spain to western Africa compared to those populations that migrate to east Africa. Crosses from these populations show an exact intermediate route. Therefore there is clearly a genetic component.

Question 6

genetic control of maternal behaviour in rodents

Answer 6

to some extent controlled by genetic components. In this case a single gene affects some behaviour.
a single gene deactivated will cause the mother to leave her litter all over the place without getting the young close to her and nourishing them

Question 7

Selection experiment on evidence for genes controlling nesting behaviour in mice

Answer 7

There is variation between how much nesting material they will drag in their cavities where they will raise young.
found that there is some variation between individuals.

in a selection experiment you breed individuals together from one end of the scale and the other end of the scale. You take the extremes and breed them together so you can effectively make 2 extreme behaviours.
from the graph you can see that there are several generations where nothing much happens but after some generations eventually the high cotton collecting continue to collect more and more cotton, where as the low cotton collectors show the same trend but less and less.

Question 8

example of interplay of both genes and environment in song dialect in birds
KEETON MARA

Answer 8

• some species have specific vocal songs but local dialects
• an example of this is white crowned sparrows
• turns out in white crowned sparrows it is a bit of both.
• There is a genetic element to learning species song, but the population specific one is learnt from the environement
• There is a critical learning period and will learn any song in this period as long as it belongs to their own species, so can learn any dialect – this is with tapes
• But if you expose birds to humans speech or live speech they will learn a whole lot more than species specific songs
• The key findings from keeton mara they will learn any dialect within their species in a critical period

Question 9

environment affecting behaviour in mice

Answer 9

o Mice were c section
o There position in the uterus was determined
o These individuals already generate specific hormones and these permeate outside of their skin to neighbouring embryos
o Influences of foetus position and the hormones on subsequent individual behaviour
o If you look at the hormone levels in this female for example you can then measure the extent to which male embryos depending whether they are sitting in the womb next to a female or male embryo and are exposed to levels of hormones from neighbouring embryos
o If there are 2 males next to an individual male then their oestrogen level is relatively low
o If you then measure in such males the aggression level the aggression level of embryos that has been sitting between 2 males are much higher than those sitting between 2 females.
o The prenatal position can determine aggression in mating
o Territory and aggression level are quite important behavioural components.

Question 10

summary for nurture vs nature

Answer 10

There is a genetic basis to all behaviours
Some behaviours have a stronger genetic component than others
Behaviour is almost never fully “genetically determined”
Environment is very important too
Behaviour is typically determined by both “nature” AND “nurture”