Okay, welcome back. This is the eighth and final unit of this course. And again, the purpose of this unit is to both summarize the course, which I've already done that's, that we did in the first module. But also take an opportunity to explore other areas where behavioral genetic research might have certain implications. These are much more speculative areas than, than what we talked about earlier in the course. But, because they're speculative they're, I think anyway, kind of interesting. And so, in this module, or in this topic I'm going to talk about behavioral genetic research and its implications, or at least its perceived implications, for personal responsibility. And I've actually broken this topic up into two modules. And one of, I, I think the most convenient ways of talking about genetic research and personal responsibility is to talk about behavioral genetics in the courtroom. And as you'll see when we get into this in a couple minutes, there truly aren't at this point a lot of examples of behavioral genetic research being brought up in the courtroom. But nonetheless, I think it, the, the examples where it has been brought up really help, at least me understand and hopefully you as well, after we talk about it, how people really think about behavioral genetic research. Not you and me but the broader public. A couple caveats before we begin. First is I'm obviously not a lawyer. And what's more, what little I know about the law, and I would emphasize little, what little I know I know about US law, and not law in other countries. And I recognize that legal systems vary across the world. The second thing I want to emphasize by way of a caveat is I'm also not a moral philosopher. And when we begin to talk about genetics and personal responsibility, we really begin to kind of cross over into the area of philosophy now that's concerned about whether or not neuroscience or genetics has implications for our, our notions of free will. I want to kind of stay away from that, what I almost perceive to be a quagmire. Soft-determinism, hard-determinism, it certainly has implication for what we'll talk about here, but mostly what I want to focus on is not the implications of those philosophical debates, but rather to talk about, to use these examples here to think about how others think about genetic material or genetic data. So, behavioral genetics and the law. Most legal systems have at their core the notion that we are generally responsible for our behavior. As I said already there are not a lot of examples of behavioral genetic research being introduced into the legal system. But when it has been introduced it's almost inevitably been introduced by the defense in order to as an attempt to mitigate the defendant's responsibility for a crime. So why might this work? Well one way people have thought about this is that there exists a continuum of genetic influence. At one end are things we didn't spent a lot of time on in this course because there aren't a lot of behavioral examples of these. These are Mendelian or single gene, I've, I've characterized these as all diseases. But we could talk about the more broadly [UNKNOWN]. I'll use the term disease here. Mendelian or single-gene diseases, where there's a very high correlation between the genotype and the phenotype. On down to the other end of the continuum here, where they're non-heritable diseases, things like head trauma, a brain tumor that develops. And so we might consider a continuum of the degree of genetic influence. We've mostly, in this course, been in this intermediate stage here, things that are heritable, but still there are also environmental influences. But something like Huntington Disease, if you've inherited the mutation for Huntington Disease, if you live long enough you will develop the symptoms of this neurological disorder. So in a sense, things up here are, are truly genetically determined whereas things down here are not. Now some people have asked the question as, as we go from acquired to genetic or they've speculated I suppose, as we go from acquired to genetic, maybe there's a complementary continuum of personal responsibility. That is, it's hard to say that somebody who's inherited the Huntington Disease, has any sort of control or personal responsibility for the symptoms of that disease. If you inherit it, you're going to get the disease, there's no treatment for it. And given that, maybe at the other end of the continuum, they the, the thinking goes is maybe we have high personal responsibility. I actually don't think this quite works, but nonetheless, I think people do tend to think about genetic information in this way. That is, as we get things that are more genetically influenced, or even genetically determined like Huntington Disease, we think that the individual has low personal responsibility for the manifestations of those phenotypes. Whereas, things that are not particularly heritable, the individual would have higher personal responsibility. Again, I don't think that this is necessarily the case. But I do think people tend to think that way. And given that they think that way, I think if you begin to introduce information like this into the courtroom, it's going to have an implications in terms of the way people process it. So genetics in the courtroom. The first example I know about involves a condition called XYY. A condition we haven't caught, talked about in this course, but it is a behavioral condition. What XYY is, is a male, remember, that if you inherit at least one X-Y chromosome, I'm sorry, if you inherit as least one Y chromosome, in humans, you're a male. But, this is a male that not only has inherited one, but also another Y chromosome. So they have 40, their karyotype has 47 chromosomes, rather than 46, so they, they have an aneuploidy condition. They have an extra Y chromosome. This actually occurs with some frequency, about one out of every 1,000 male births is an XYY birth, and we know a lot about the phenotype for males with XYY. They're usually a little bit taller than the average male, on average about three years, three, I'm sorry, three inches taller. They're a little bit slender. They tend to have slightly lower IQs than the average. So on the, on the order of about ten IQ points below the average IQ of a hundred. They're not in the intellectually disabled end of the continuum, but a little bit low average IQs. And they also produce higher levels of testosterone than males that have just one Y chromosome. Almost 50 years ago, now, Pat Jacobs, and Pat Jacobs is an eminent, British, geneticist, made an observation and she went into the couple penal institutes in in Britain and she karyotyped males there who were in, in prison and she found that there was an over representation of XYY males than you would expect, based upon the representation of the population of one out of every thousand males. I can't remember exactly how high the elevation was, but there definitely was a significant increased representation of XYY males in the penal institutions there. This lead to a lot of controversy at the time and it also lead to the notion that what a XYY male was, was somehow a super aggressive male. Higher levels of testosterone, over-representation in prison. We now know by subs, subsequent research, large scale studies coming out of other European countries like Denmark, that the XYY karyotype is in fact over represented in, in among males who have committed crime. But it's not that they're over represented in crimes of aggression. They, they tend to actually be over represented in crimes against property rather than violent crimes. Nonetheless, back in the 60s when Pat Jacobs first reported the results this notion was the notion came along in the popular media that having an extra Y chromosome made you a super and likely an aggressive male. So her research was actually published right at the same time that Richard Speck did something rather heinous. Maybe some of you know about Richard Speck, he's a, a rather unseemly individual. In 1966, he snuck in to a dorm room a dorm in Chicago and murdered, brutally murdered, eight student nurses. Turned out that Richard Speck was a thin man, and he was little bit taller than average. He wasn't really tall. I think he was about six feet one inches tall. And so a geneticist contacted the defense team that was trying to defend, defend Richard Speck here, and su, suggested that he might have an extra Y chromosome in, he had this crime, this research by Pat Jacobs had just come out. And so the defense team decided to karyotype Richard Speck. As it turned out, here didn't have an extra Y chromosome, but that almost didn't matter. The media ended up erroneously reporting that he was XYY, which kind of reinforced the notion in the general population that having this extra Y chromosome was associated with elevated levels of aggression in men. And he ended up being convicted and he died in jail but unfortunately there's still people today who think that he had this atypical karyotype. A more successful use of behavioral genetic research in the courtroom is the case, another American case of a man named Bradley Waldroup who lived in Tennessee. Bradley Waldroup, in 2006, he was divorced or separated from his wife, and when he went to pick up his children, at his wife's residence, he actually brought with him a gun and he actually had told people that his wife was going to die. And when he came to pick up the kids he actually pulled out the gun, shot his wife's best friend eight times killing her, and then picked up a machete and, and took the machete to his wife, ex wife and almost killed her. She survived fortunately. The defense, there was actually no question in the Waldroup case that he had done the crime, that he had actually killed this woman and attempted to kill his wife. That was indisputable. So the defense had to try a different strategy. And the strategy they, they hit on was rather then trying to defend him against a crime he obviously had committed, is to try to mitigate his responsibility for the crime, by arguing that Waldroup carried a high risk allele, at this particular gene, called the MAO-A gene that I'm going to get to in a second, and he also had a history of childhood abuse. Now why might that be relevant? Well first, the MAO gene. MAO-A is an enzyme, and it's an enzyme that breaks down neurotransmitter levels in your brain. And in particular, it breaks down one neurotransmitter called serotonin. And there's an old hypothesis for which there is some empirical support. In the literature that says that aggression is associated, or violence is associated with high levels of serotonin. And part of the evidence to support this explanation is the observation on animals that if you eliminate this enzyme, they end up with high levels of serotonin and they're particularly aggressive animals. These are usually rodents. Further supporting this enzyme for which there's a gene and aggression was an observation that goes back to 1993 by this group here, Brunner et al from, from Holland, where they studied a Dutch pedigree. It turns out that the gene that codes for this enzyme is on the X chromosome. Recall that men, males only have one X chromosome, females have two. They had this Dutch pedigree, this family of Dutch individuals where many males in the family, and this is the pedigree here, many males in the family had a condition, and the condition was characterized by them having very high levels of impulsive aggression. There's two ways that psychologists who study aggression think about aggression. Sometimes we're aggressive impulsively. That is we don't really think about things, we just act out. Other times we are impulsive instrumentally. We premeditate our violent behavior. In this case, these men were impulsively aggressive, they also suffered from an intellectual disability. What Brunner and his colleagues observed is they also had very low levels of this particular enzyme that breaks down serotonin. So presumably, they had high serotonin levels. When they went to study the gene on the X chromosome for MAO-A, indeed, these men who all had this impulsive aggression condition, had a stop code on, a mutation, in the gene that led to an abnormally early termination of the gene product, the enzyme. So they basically didn't have a functional form of the enzyme. That's why they have very low MAO-A activity and presumably high levels of serotonin. And possibly probably explaining their levels of impulsive aggression. Now fortunately, the mutation of these men in this Dutch pedigree had is very, very rare. In fact, it's never been observed in another individual. It might exist in someone else, but it just hasn't been observed. Nonetheless, ten years, approximately ten years after the Brunner study, another study came out in science by a group we've already talked about earlier in this course. Caspi Moffit and their colleagues that are studying this cohort of New Zealand men who they've, started at birth and then followed up over time. And what they reported, and this is a very highly cited and important study in psychiatry, what they reported is a gene by environment interaction. They didn't study the same variant that the Brunner people studied because that's a rare variant. What they studied was actually a polymorphism, a genetic variant in the promoter region of this gene. Such that again, because males only have what one X chromosome, they have one allele or the other at this particular polymorphism. Either you have a low activity form of the enzyme, because of the variant in the promoter, or a high activity. So they still have activity here, but they don't have as much activity as here. They then cross-classified the men, these are all men, as to whether or not they'd experienced childhood maltreatment. And what they found is that if they didn't experience childhood maltreatment, the polymorphism didn't matter. If they had experienced severe childhood maltreatment, it mattered. They were more aggressive here than here. So it's actually a gene by environment interaction. Adiath is a stress form of the gene by environment interaction. Back to Barry Waldroup, back to Waltrop, Bradley Waldroup, his defense team, found out that he was carrying this allele, and he also had a history of childhood maltreatment. So they were appeal, they're going to appeal to this particular scientific finding. Now, the MAO gene has gained quite a reputation subsequent to the research by Brunner and Caspi. And I'm, I suspect that neither Caspi or Brunner are happy with the reputation the MAO gene has gained. It's been called the murder gene, and you can follow this link here if you want to read about how it's been characterized as the murder gene, the warrior gene, this link, or the rage gene. And actually what I want to do is kind of stop here, and ask you to look at maybe the first two, three, or four minutes if you want, you can look at the, you can watch the whole documentary it's 45 minute documentary that talks about this particular gene. And, the, the documentary, here's a link here. We'll put a link on the, the course webpage. The documentary begins with the question, are some people born violent? And as you'll see, the answer to that question that they come to in that documentary, and it's a National Geographic documentary, is that, yes, some people are born violent and they're born violent because they inherit particular variant of this gene. And what I, the reason I'm asking you to look at this documentary is to just see the, I what I would argue is the discordance of what we've talked about in this course and how things, how be able genetic information gets presented to the general public. So, take a look at that and then we'll come back and we'll continue with this story in the next module. Thank you. [BLANK_AUDIO]
