In the first real class session, Professor Sapolsky introduces the concept of behavioral evolution and begins examining how selective pressures would favor certain behaviors. In so doing he examines game theory in depth, highlighting the benefits and drawbacks of the various approaches.
He presents two skulls and gives an overview of what's coming. Based simply on the shape of the skulls relative to each other, we can figure out a whole range of behaviors, including mate selection, probability of twins, parental behavior and more. He next runs through a series of questions and answers using the framework of pair-bonding species and tournament species.
Professor Sapolsky points out the silliness of identifying biological elements as amazing based simply on their congruence with necessity since the animal, be it a giraffe or desert rodent, wouldn't be around if its biological components weren't sufficient to produce life. Thus a giraffe's heart will be strong enough to distribute blood throughout its body. When it fails to do so the giraffe dies. This same logic, built around evolutionary principles, enables us to figure out all kinds of behaviors.
Darwin is not the originator of the idea of evolution. People knew about that, but he came up with a mechanism, natural selection, for evolution. Alfred Russell Wallace was a co-inventor of the natural selection theory.
This notion is built upon the following logic.
1. There are traits that are heritable. Broadly speaking this means they are genetic and can be passed on to the next generation (he will later examine this in detail and demonstrate the massive power of environmental influences on what "heritable" really means scientifically).
2. There is variability among those traits.
3. Some versions of those traits are more adaptive than others. Some are more fit. He notes that it's not about survival, but rather reproductive success to send those traits on to the next generation.
4. Mutations are also important as they can introduce massive changes.
He notes that personification will be used to keep things simple and understandable, but the idea of the animal wanting to do something is dubious - there isn't necessarily long term planning to pass on genes, at least not on a conscious level. It's more behaviors that happen without an evolutionary intent. This is easy enough to understand among people too; we select our mates based on things we like, rarely based on a plan to pass on the most advantageous genes to the next generation to get ourselves a high Darwin score. This may happen as a by-product but it's not going to be the leading edge in the decision making process.
Animals do not behave for the good of the species. The concept of Group Selection was advanced by Wynne-Edwards, arguing that animals would act for the benefit of all. The advantage of the group selection theory is that it accounts for behaviors that are good for the group as a whole but not necessarily for individuals within the group. But the theory is not generally viewed as being correct. The currently accepted theory is that animals behave to pass on as many copies of their genes as they can (this may ultimately be correct but it's worth pausing before wholeheartedly accepting this as the defining force since we just covered the argument on personification which suggested that animals aren't consciously acting to pass on as many genes as possible.)
The building blocks of reproductive success as the mechanism for selection are as follows:
1. Individual selection. Sometimes the behaviors of an animal is about reproducing. The notion is that sometimes a chicken is an egg's way of making another egg. That is that traits and behaviors are there to drive mating and create more of that type of thing.
2. Sexual selection. Picking for traits that carry no adaptive value but for whatever reason the opposite sex likes individuals that look that way. These traits will then become more common. This can be opposed by natural selection, for example a brightly colored fish may be more attractive to the lady fish but also more likely to be predated because it stands out. So the two can be in conflict and create interesting challenges for the individual.
3. Kin selection. Identical twins share 100% of their genes, siblings 50%. The closer the relative, the more genes shared in common. From the standpoint of individual selection, an identical twin can pass on "their" genes by the twin at their own expense. So it makes sense to sacrifice yourself for two brothers or eight cousins. And thus we have evolution favoring cooperation among relatives.
4. Rock-paper-scissors scenario. In this situation each organism has the potential to harm one of the others but doesn't do so because the overall impact of those actions would hurt the original organism.
Cooperative behaviors are also frequently seen. There are many situations in which cooperative behavior yields a better result than acting alone. But the efforts must be similar, creating a situation of reciprocal altruism. Remarkably this is even seen in single celled organisms. He gives an example of bacteria and their teaming up to form new bacteria. One side has to act as the stalk, the other gets to be the fruiting body. Being the fruiting body is advantageous and bacterium will sometimes try to cheat in the relationship. When this happens the other bacterium is less likely to cooperate the next time around.
Cheating is thus a big part of social relationships, so animals have also developed skills at detecting when someone else is cheating. Animals tend to be better at picking up on cheating than noticing spontaneous altruism.
Next he moves into the topic of Game Theory. He covers various aspects and highlights in conclusion that forgiving tit for tat ends up out-competing the other strategies. The basic building block of game theory starts with the Prisoner's Dilemma in which two criminals are caught and encouraged to roll over on the other. The possible scenarios are that both do so, one does so and the other doesn't, and that neither does so. Prisoner A gains the most benefit from ratting out Prisoner B when B has not ratted him out. Second most benefit is if neither rats each other out, then if both rat each other out, and the worst outcome is if A keeps quiet and B rats him out (if both do he gains cooperation points). [Note that Professor Sapolsky uses cheat versus cooperate here, but I think that's slightly confusing since we've all seen too many Law & Order episodes and associate cooperating with the police as meaning ratting the other guy out. Here cooperate = keep quiet.]
Studies have shown that brain centers responsible for pleasure light up during times of stabbing the other guy in the back and during times of cooperation. There is a pronounced gender difference as to when these areas are activated. He does not tell us which gender lights up when, so I suppose that will remain a mystery...
Daniel Ellsburg was a game theorist working for the Pentagon. He is best known for turning over thousands of pages of internal documents, "The Pentagon Papers," to the NY Times. These pages were internal planning pages and documents that demonstrated an entirely different set of goals in the Vietnam War than had been publicly proclaimed. [An in depth study of the papers' content as well as the media is found in Noam Chomsky's Manufacturing Consent.] Ellsburg wrote a paper on the optimal benefits of perceived madness. He detailed the advantages of madness (madman theory), which was an important game strategy within the context of the Cold War and the threat of nuclear warfare and mutually assured destruction.
Vampire bats are up next. The mothers suck the blood out of other animals, such as cows, and then bring the blood back for the kids. They are social animals and will feed others' offspring as well. Research has been done in which mother vampire bats were captured and had their blood sacs filled with air so that it would appear to the other bats that they had a lot of good blood to share. When they returned to the nest and did not share, others took note and were then didn't help the research bat's offspring the next time they returned with blood food.
Stickleback fish also engage in tit for tat strategies. As does the Black Hamlet Fish, which is also capable of changing its sex. Tit for tat strategies are used by this fish when the other mate doesn't carry his or her load by being the female as often as the original fish (higher costs).
Reciprocal social altruism also includes consideration for other domains of behavior, so an animal may be worthless in one area but valuable in another and studies have shown that social groups will accept and value this approach. He mentions examples of naked mole rats and lions.
Professor Sapolsky points out the silliness of identifying biological elements as amazing based simply on their congruence with necessity since the animal, be it a giraffe or desert rodent, wouldn't be around if its biological components weren't sufficient to produce life. Thus a giraffe's heart will be strong enough to distribute blood throughout its body. When it fails to do so the giraffe dies. This same logic, built around evolutionary principles, enables us to figure out all kinds of behaviors.
Darwin is not the originator of the idea of evolution. People knew about that, but he came up with a mechanism, natural selection, for evolution. Alfred Russell Wallace was a co-inventor of the natural selection theory.
This notion is built upon the following logic.
1. There are traits that are heritable. Broadly speaking this means they are genetic and can be passed on to the next generation (he will later examine this in detail and demonstrate the massive power of environmental influences on what "heritable" really means scientifically).
2. There is variability among those traits.
3. Some versions of those traits are more adaptive than others. Some are more fit. He notes that it's not about survival, but rather reproductive success to send those traits on to the next generation.
4. Mutations are also important as they can introduce massive changes.
He notes that personification will be used to keep things simple and understandable, but the idea of the animal wanting to do something is dubious - there isn't necessarily long term planning to pass on genes, at least not on a conscious level. It's more behaviors that happen without an evolutionary intent. This is easy enough to understand among people too; we select our mates based on things we like, rarely based on a plan to pass on the most advantageous genes to the next generation to get ourselves a high Darwin score. This may happen as a by-product but it's not going to be the leading edge in the decision making process.
Animals do not behave for the good of the species. The concept of Group Selection was advanced by Wynne-Edwards, arguing that animals would act for the benefit of all. The advantage of the group selection theory is that it accounts for behaviors that are good for the group as a whole but not necessarily for individuals within the group. But the theory is not generally viewed as being correct. The currently accepted theory is that animals behave to pass on as many copies of their genes as they can (this may ultimately be correct but it's worth pausing before wholeheartedly accepting this as the defining force since we just covered the argument on personification which suggested that animals aren't consciously acting to pass on as many genes as possible.)
The building blocks of reproductive success as the mechanism for selection are as follows:
1. Individual selection. Sometimes the behaviors of an animal is about reproducing. The notion is that sometimes a chicken is an egg's way of making another egg. That is that traits and behaviors are there to drive mating and create more of that type of thing.
2. Sexual selection. Picking for traits that carry no adaptive value but for whatever reason the opposite sex likes individuals that look that way. These traits will then become more common. This can be opposed by natural selection, for example a brightly colored fish may be more attractive to the lady fish but also more likely to be predated because it stands out. So the two can be in conflict and create interesting challenges for the individual.
3. Kin selection. Identical twins share 100% of their genes, siblings 50%. The closer the relative, the more genes shared in common. From the standpoint of individual selection, an identical twin can pass on "their" genes by the twin at their own expense. So it makes sense to sacrifice yourself for two brothers or eight cousins. And thus we have evolution favoring cooperation among relatives.
4. Rock-paper-scissors scenario. In this situation each organism has the potential to harm one of the others but doesn't do so because the overall impact of those actions would hurt the original organism.
Cooperative behaviors are also frequently seen. There are many situations in which cooperative behavior yields a better result than acting alone. But the efforts must be similar, creating a situation of reciprocal altruism. Remarkably this is even seen in single celled organisms. He gives an example of bacteria and their teaming up to form new bacteria. One side has to act as the stalk, the other gets to be the fruiting body. Being the fruiting body is advantageous and bacterium will sometimes try to cheat in the relationship. When this happens the other bacterium is less likely to cooperate the next time around.
Cheating is thus a big part of social relationships, so animals have also developed skills at detecting when someone else is cheating. Animals tend to be better at picking up on cheating than noticing spontaneous altruism.
Next he moves into the topic of Game Theory. He covers various aspects and highlights in conclusion that forgiving tit for tat ends up out-competing the other strategies. The basic building block of game theory starts with the Prisoner's Dilemma in which two criminals are caught and encouraged to roll over on the other. The possible scenarios are that both do so, one does so and the other doesn't, and that neither does so. Prisoner A gains the most benefit from ratting out Prisoner B when B has not ratted him out. Second most benefit is if neither rats each other out, then if both rat each other out, and the worst outcome is if A keeps quiet and B rats him out (if both do he gains cooperation points). [Note that Professor Sapolsky uses cheat versus cooperate here, but I think that's slightly confusing since we've all seen too many Law & Order episodes and associate cooperating with the police as meaning ratting the other guy out. Here cooperate = keep quiet.]
Studies have shown that brain centers responsible for pleasure light up during times of stabbing the other guy in the back and during times of cooperation. There is a pronounced gender difference as to when these areas are activated. He does not tell us which gender lights up when, so I suppose that will remain a mystery...
Daniel Ellsburg was a game theorist working for the Pentagon. He is best known for turning over thousands of pages of internal documents, "The Pentagon Papers," to the NY Times. These pages were internal planning pages and documents that demonstrated an entirely different set of goals in the Vietnam War than had been publicly proclaimed. [An in depth study of the papers' content as well as the media is found in Noam Chomsky's Manufacturing Consent.] Ellsburg wrote a paper on the optimal benefits of perceived madness. He detailed the advantages of madness (madman theory), which was an important game strategy within the context of the Cold War and the threat of nuclear warfare and mutually assured destruction.
Vampire bats are up next. The mothers suck the blood out of other animals, such as cows, and then bring the blood back for the kids. They are social animals and will feed others' offspring as well. Research has been done in which mother vampire bats were captured and had their blood sacs filled with air so that it would appear to the other bats that they had a lot of good blood to share. When they returned to the nest and did not share, others took note and were then didn't help the research bat's offspring the next time they returned with blood food.
Stickleback fish also engage in tit for tat strategies. As does the Black Hamlet Fish, which is also capable of changing its sex. Tit for tat strategies are used by this fish when the other mate doesn't carry his or her load by being the female as often as the original fish (higher costs).
Reciprocal social altruism also includes consideration for other domains of behavior, so an animal may be worthless in one area but valuable in another and studies have shown that social groups will accept and value this approach. He mentions examples of naked mole rats and lions.
Behavior
Aggression Variability Reproductive Success Female Choice Lifespan Parental Behavior Twins Abandonment |
Big Male, Small Female
Tournament species are more aggressive. TS has a high level of variability with top few having most success. 95% from 5%. Good genes for offspring - big, strong. After all it's all she's getting. Lower - more fighting and aggression. Virtually no male parental behaviors. Twins are rare; female is responsible for offspring. Rare - the male won't be caring for the offspring. |
Small Male, Small Female
Pair-bonding species are less aggressive. Relatively similar levels, 1-2 on average. Resources and parental skills. Longer and more similar to females. A lot of parental behavior - looking for male who is as close to being a female as possible. Frequent - female has help. More common since the male will care for the offspring. |
So the world of sexual dimorphism comes forth (dimorphism - different sizes). The parental behavior includes things like courtship, such as a male bird bringing a female bird a gift of a worm, which shows competence.
He then provides additional explanation of the difference between tournament species and pair-bonding species. In TS the males have the bright plumage, the bid bodies, and the impressive fights over females. In pair bonding species the size is more similar, the females have more options and the males are more paternal.
Baboons, chickens, some fish - tournament species.
Marmosets, tamarins - pair bonding species.
Humans are, of course, right in the middle. Which helps explain a lot of male-female problems.
He then provides additional explanation of the difference between tournament species and pair-bonding species. In TS the males have the bright plumage, the bid bodies, and the impressive fights over females. In pair bonding species the size is more similar, the females have more options and the males are more paternal.
Baboons, chickens, some fish - tournament species.
Marmosets, tamarins - pair bonding species.
Humans are, of course, right in the middle. Which helps explain a lot of male-female problems.