Lecture 3 Flashcards
Discuss Dawkins and the selfish gene
This is the idea that there is a gene-centred view of evolution as opposed to organism centred. The adaptive genes improve fitness and it explains why one would be selfless to those they are related to as it will improve their genes survival still. It believes that our bodies are just ‘vehicles’ for genes. This idea is often misinterpreted because the genes making decisions is only metaphor. Also people don’t like it because removes free will. This idea argues against group selection.
Define altruism
An act that benefits the recipient at a cost to the donor. These costs and benefits affect one’s fitness. An example of this is alarm calls among prairie dogs which costs the sender but benefits everyone else, e.g. family members.
Discuss the coefficient of relatedness
This is calculating the probability that two individuals will share the same genes via descent. For example, the probability that you will share a gene with your mother is 0.5 because her haploid gamete merged with your father’s so inherit half of her genes. It is important to remember that you are only calculating a PROBABILITY. You also share 0.5 with your siblings. With half siblings, you only share your mother’s genes so the probability of sharing a particular gene is 0.25.
Discuss Hamilton’s rule
This is a calculation that calculates the likelihood of one acting altruistically to another. It’s calculated via: r B > C. r = relatedness. B = benefit. C = cost. For example, it’s more beneficial for your genes if you ensure your siblings’s 4 children survive compared to ensuring your one child survives = (0.5 X 4) > 1. This theory explains kin selection. The more related we are to someone, the more altruistic we act. This is supports the idea of prairie dogs and alarm calls; they are more likely to make an alarm call if their close relatives are in the group. It is important to remember that evolution doesn’t always favour kin selection, it is a tradeoff (rB < C). Reciprocal altruism can occur with non-related others but people are more likely to cheat the system.
How can you test for kin selection?
Ask people about their perceived investment in others.
Actual investment; look at wills, conduct experiments
Lack of investment; child neglect, infanticide
Give empirical evidence for human kin selection
2 studies
When looking at people’s wills, their offspring inherited the most and this then reduced with relatedness. The exception of this was spouses, however, they could provide more children, meaning more genes are passed on and they care for the children they already have.
Also, another study found that when asked to stand in a ski pose against the wall, they would do it for longest when there was a personal reward. This length of time then reduced when the reward was for a relative. The less related, the less time in the pose.
Discuss paternity certainty and investment
Fathers have potential paternity uncertainty because the mother could have mated with other males. However, mothers don’t have this issue as they know that it is 100% their child. This means that fathers are more likely to not invest in their children. One study found a correlation between resemblance and paternal investment and also a correlation between perceived faithfulness of partner and paternal investment. However, you can’t infer cause and effect.
Another study morphed the participant’s face with a child’s face and asked the participant how much they would invest in the child. Men said they would invest in the child more than the women, showing that they depend on resemblance more than mothers.
This can also be applied to siblings. Full siblings invest more in each other compared to half siblings even in mormon societies where everyone should be treated equally. Also one study found that maternal grandparents invest more than paternal grandparents.
Discuss kin selection and reproductive value
Because of trade offs, kin selection favours younger family members as they have more reproductive value and can reproduce and pass on your genes. This was found in a study as the result showed that old people would save younger members compared to older members. Young members had no preference in who they would save because older members care for them and younger members have reproductive value. (Hamilton’s rule).
Why does adoption occur as it doesn’t follow the idea of the selfish gene
The only explanation is that there is no cost because the couples are usually infertile. However, it doesn’t follow Hamilton’s rule at all as there is no relatedness.
Is the idea of Hamilton’s rule a conscious or subconscious mechanism?
Subconscious.
Who loses out from kin selection?
When looking at cases of homicide, it is evident there are significantly less cases of homicide among related people. Homicides are most common among either spouses or non-relatives.
Additionally, the likelihood of infanticide is significantly higher, although still extremely uncommon, among step-parents. Perhaps due to the lack of genetic similarity. These findings were independent of personality.
This does not show that evolution has selected murder to be advantageous, it shows that we have developed mechanisms against particular murder and these mechanisms are less effective among non-kin.
Also, step parents aren’t always violent because there can be reciprocal benefits between them and the child, culture can effect their violence as well and their altruistic reputation is at stake if they are violent to the child.
How can you explain why some people are violent to kin?
Sometimes violence occurs among kin because it can benefit you more than ensuring that kin survives. For example, there can be great inheritance benefits, this happened among Vikings.
How does one decide whether to be altruistic in terms of reciprocal altruism?
People use the Prisoner’s dilemma for this. If you’re meeting someone on a one off and you don’t know whether they will act reciprocally then it’s best not to trust them. However, if you meet them repeatedly, then it’s best to be altruistic. The Prisoner’s dilemma argues that it’s not always best to be cooperative; if you both cooperate and lie to the police then you will get minimal jail time (1). If you betray and they cooperate you get off free (0). If they betray and you cooperate then you get the worst jail time (3). If you both betray then you both get jail time (2). Therefore, you are less likely to have a bad outcome if you betray. Costs = Betray; 0 + 2 = 2. Cooperate; 1 + 3 = 4.
Also, there are cultural impacts on reciprocal altruism. If one lives in a small village then they are a lot more likely to be altruistic as it is more likely that it will be reciprocated and there are higher rates of kinship. However, the information exchanged is usually negative; telling someone where something isn’t, e.g. ‘you won’t catch any fishes there’, rather than telling them where the fish actually is. This way it benefits yourself and others.
Discuss how food sharing can be beneficial to one’s fitness
This is called tolerated theft. It’s the idea that the cost of defending your food from everyone else is higher than the benefit of keeping it all for yourself. For example, when you are full and they’re hungry, they are more likely to win the fight as they have more incentive. This also depends on marginal value; the value of a food resource changes as time goes on.
Additionally, sharing out a rare resource is an effective way to show off to the females in the group and achieve high status. There could also be cultural constraints on being selfish and rejected from a group.
Therefore, group membership can promote non-selfish behaviour.
Describe Mulder’s study
When there is a lot of competition over resources, it can affect altruism among kin due to Hamilton’s rule. They looked at a society where land was limited and there was large variation of land ownership in the population. They found that wealth affects the amount of kin altruism, this was especially relevant in paternal relatives. The wealthier families tended to ensure the mortality of relatives more so than poorer families; nepotism.
