Quick recap - inherited has to do with items passed down that are consistent, while heritability is about the independence of genes relative to environment. Professor Sapolsky selects a terrible example with the whole five fingers thing since the polydactyls in the crowd are well aware that it's actually a heritable trait given that having five or six fingers will be based on genetics whether you're in Brooklyn or Yemen - know that family's history and you've got more predictive power than knowing geography. Heritability is really about the environment's influence, not the gene's influence (technically the definition runs the other way, but the manner in which heritability is established is all about where the genes are expressed. If they are what they are no matter where, then it's heritable. If variation pops up based on environment, then it's not heritable.) In the end the point he is hammering home is that very little of what comes to define us will turn out to be truly heritable - most everything will be about the gene-environment interaction and this opens up a Pandora's box when it comes to human behavioral biology and what it means to have this or that behavior, disease, or even achievement, a topic he will sum up in grand fashion in the closing lecture.
Epigenetics is about the manner in which culture affects biology.
Next is the Chutes and Ladders example. It takes these Stanford students a little too long to inquire about the magnitude and accompanying significance of the difference...Again, he's trying to highlight to them to not get caught up in the buckets/technicalities - always be aware of the bigger picture before assigning meaning to any measure of better or worse.
For example, he cites a study done in Norway and published in Science that demonstrated that first born children had higher IQ scores than second born children. In the end, though, the point that was missed was that the difference was miniscule and not statistically significant. A couple of side points. 1 - not all first born kids had higher IQ's than second born kids, so it isn't deterministic and 2 - by definition one of these is going to be higher than the other whether there's any meaning to it or not. The latter point is demonstrated by another element in the study - at age 12 the latter born kids tended to have higher IQ's. Ultimately there will always be some difference but it doesn't mean it matters.
This 30 minute section seems silly and overdone at first, but bear in mind that employers love to hand out standardized tests to assess applicants, colleges rely on ACT, SAT, LSAT, GRE and MCAT scores to tell them what kind of person you are, so on and so forth and many of these scores and apparent differences have a decent chance of being relatively meaningless. In a world that is increasingly statistical and data driven, a lot of the data are overemphasizing those boundary lines and creating false truths.
Rat studies demonstrate that they recognize relatives and are able to do so based on urine markers. For this to happen there must be at least these two things - qualitative differences and a reception area within the brain that can identify these. Just as the immune system is an example of juggling around protein combinations, so too will the body create its own protein markers. This stretch of genes is called the major histocompatability complex (MHC) and it is crucial in understanding this topic, but, more importantly, auto-immune disorders.
The protein signature is slapped onto all of the organism's cells to identify them as "us." Cells that don't have this are "them." One of the roles of the thymus is to screen immune cells to insure they can tell the difference. When they can't, you get nasty results when the immune system attacks itself. The MHC is also a major issue when organ transplantation is done because the new organ is "them" and accordingly the immune system gets geared up to attack it. This is why recipients end up on immunosuppressant drugs. It is also why stem cell research is likely critical to our capacity to regenerate damaged cells and organs; in addition to having the right DNA, it's also "us."
A nasty trick hat can be played by invaders, such as trypanosoma brucei, involves changing the protein coat that it displays. Although the immune system will figure out there's an issue, by the time antibodies are formed to attack the original form, the shield has been changed and the invader continues to reproduce "itself."
Even worse is schistosomiasis - what these buggers do is cloak themselves in your MHC, grabbing the protein sheath from your cells and hiding out as if they were your own cells.
And worse than that are cancerous cells which can be cloaked in your MHC proteins and thus evade attack. If apoptosis doesn't get them, you end up in treatment.
The MHC proteins can become soluble and are thus exuded in saliva, perspiration, urine, etc. and can become genetic markers at some level.
Oxytocin and vasopressin tune up the cells that recognize MHC signals, especially around the time of pregnancy and giving birth. This marks the child and leads to nursing and resource investment.
Research suggests a possible mutation in the genes coding for oxytocin and vasopressin in families with autism, where there are major deficits (or differences) in social communication, bonding, etc.
Much to our delight, it turns out that new neurons are generated, primarily in the hippocampus (learning) and the olfactory system (scent, during pregnancy and post natal). Here he throws out an interesting hypothesis. During the time you're pregnant you're restructuring your olfactory system, taste is driven by olfactory cues, and it's no wonder that stuff smells weird, foods taste weird and you get odd cravings. Which makes more sense than the notion that changes in diet and morning sickness are caused by evolutionary attempts to protect the fetus from fetid meat - were women eating fetid meat before the pregnancy?
An interesting study with baboons found that dominance reversal cries were very interesting to the group if the two were not relatives but not interesting if they were. To wit, if #4 and #27 had a squabble and were relatives, no one cared that much if #27 gave a dominant howl and #4 a submissive one. But if they were not relatives, the baboons were instantly tuned in to figure out why #4 was submitting to #27. Crazy relatives get no attention. A human parallel would be employees not getting all worked up over the intern/mail clerk son of the CEO arguing with Dad and getting a concession but being very confused and attentive if a mid-level manager successfully rips him a new one.
Imprinting is another method for recognizing relatives. The learning is innate but the process is experiential.
The fusiform cortex (or fusiform face area) is a section of the brain within the cortex that appears to be centrally involved in facial recognition. Show someone a portrait, picture or even a good cartoon of a known face and this part lights up. However, show an autistic person a portrait, picture or even a good cartoon and it doesn't. This brain area may be centrally involved in cognitive understanding of what's a relative, or at least a known person. For autistics, mother=armchair=stranger.
Epigenetics is about the manner in which culture affects biology.
Next is the Chutes and Ladders example. It takes these Stanford students a little too long to inquire about the magnitude and accompanying significance of the difference...Again, he's trying to highlight to them to not get caught up in the buckets/technicalities - always be aware of the bigger picture before assigning meaning to any measure of better or worse.
For example, he cites a study done in Norway and published in Science that demonstrated that first born children had higher IQ scores than second born children. In the end, though, the point that was missed was that the difference was miniscule and not statistically significant. A couple of side points. 1 - not all first born kids had higher IQ's than second born kids, so it isn't deterministic and 2 - by definition one of these is going to be higher than the other whether there's any meaning to it or not. The latter point is demonstrated by another element in the study - at age 12 the latter born kids tended to have higher IQ's. Ultimately there will always be some difference but it doesn't mean it matters.
This 30 minute section seems silly and overdone at first, but bear in mind that employers love to hand out standardized tests to assess applicants, colleges rely on ACT, SAT, LSAT, GRE and MCAT scores to tell them what kind of person you are, so on and so forth and many of these scores and apparent differences have a decent chance of being relatively meaningless. In a world that is increasingly statistical and data driven, a lot of the data are overemphasizing those boundary lines and creating false truths.
Rat studies demonstrate that they recognize relatives and are able to do so based on urine markers. For this to happen there must be at least these two things - qualitative differences and a reception area within the brain that can identify these. Just as the immune system is an example of juggling around protein combinations, so too will the body create its own protein markers. This stretch of genes is called the major histocompatability complex (MHC) and it is crucial in understanding this topic, but, more importantly, auto-immune disorders.
The protein signature is slapped onto all of the organism's cells to identify them as "us." Cells that don't have this are "them." One of the roles of the thymus is to screen immune cells to insure they can tell the difference. When they can't, you get nasty results when the immune system attacks itself. The MHC is also a major issue when organ transplantation is done because the new organ is "them" and accordingly the immune system gets geared up to attack it. This is why recipients end up on immunosuppressant drugs. It is also why stem cell research is likely critical to our capacity to regenerate damaged cells and organs; in addition to having the right DNA, it's also "us."
A nasty trick hat can be played by invaders, such as trypanosoma brucei, involves changing the protein coat that it displays. Although the immune system will figure out there's an issue, by the time antibodies are formed to attack the original form, the shield has been changed and the invader continues to reproduce "itself."
Even worse is schistosomiasis - what these buggers do is cloak themselves in your MHC, grabbing the protein sheath from your cells and hiding out as if they were your own cells.
And worse than that are cancerous cells which can be cloaked in your MHC proteins and thus evade attack. If apoptosis doesn't get them, you end up in treatment.
The MHC proteins can become soluble and are thus exuded in saliva, perspiration, urine, etc. and can become genetic markers at some level.
Oxytocin and vasopressin tune up the cells that recognize MHC signals, especially around the time of pregnancy and giving birth. This marks the child and leads to nursing and resource investment.
Research suggests a possible mutation in the genes coding for oxytocin and vasopressin in families with autism, where there are major deficits (or differences) in social communication, bonding, etc.
Much to our delight, it turns out that new neurons are generated, primarily in the hippocampus (learning) and the olfactory system (scent, during pregnancy and post natal). Here he throws out an interesting hypothesis. During the time you're pregnant you're restructuring your olfactory system, taste is driven by olfactory cues, and it's no wonder that stuff smells weird, foods taste weird and you get odd cravings. Which makes more sense than the notion that changes in diet and morning sickness are caused by evolutionary attempts to protect the fetus from fetid meat - were women eating fetid meat before the pregnancy?
An interesting study with baboons found that dominance reversal cries were very interesting to the group if the two were not relatives but not interesting if they were. To wit, if #4 and #27 had a squabble and were relatives, no one cared that much if #27 gave a dominant howl and #4 a submissive one. But if they were not relatives, the baboons were instantly tuned in to figure out why #4 was submitting to #27. Crazy relatives get no attention. A human parallel would be employees not getting all worked up over the intern/mail clerk son of the CEO arguing with Dad and getting a concession but being very confused and attentive if a mid-level manager successfully rips him a new one.
Imprinting is another method for recognizing relatives. The learning is innate but the process is experiential.
The fusiform cortex (or fusiform face area) is a section of the brain within the cortex that appears to be centrally involved in facial recognition. Show someone a portrait, picture or even a good cartoon of a known face and this part lights up. However, show an autistic person a portrait, picture or even a good cartoon and it doesn't. This brain area may be centrally involved in cognitive understanding of what's a relative, or at least a known person. For autistics, mother=armchair=stranger.
