8. Recognizing Relatives

Video ready, click here to close ×

(April 16, 2010) Robert Sapolsky discusses various methods of innate recognition of relatives between animals and humans through protein signatures, olfactory cellular mechanisms, cognitive, and sensory processes. He explores the importance of relatedness in animal mating/ovulation cycles and other phenomena that show how organisms identify each other.

Stanford University

Stanford Department of Biology

Stanford University Channel on YouTube



  • Robert Sapolsky is a "Satanic" Jew Supremacist

  • i am an English literature student professor sapolsky and I'm loving the course! it is revolutionizing the way i think about culture and history. more people need to talk about the intersections between biology and culture which together shape our reality.

  • I think Margret Thatcher's own kids probably turned towards the other smell 😉

  • Sorry, but there is a profound logical error. I assume you assume that IQ means messuring of intelligence. It is messuring whether questions are answerde in a certain way and whether you think in a certain way. Normaly – I assume- one got more time for the first kid- a kind of drill starts.

  • The Israeli Kibbutz study has now been refuted: they interviewed many of the kids again and found there was an attraction in many cases, though they didnt marry. However there are lots of other studies that show the Westermarck effect is real and interesting.

  • Is the olfactory system of a newborn's mother, which has been enhanced by oxytocin and vasopressin, sensitive enough for the mother to feel uneasy if her newborn is switched with another newborn?

  • Thank you, Dr. Sapolsky for this brilliant introductory course.
    Lecture notes for this course would be very useful. And I am very sorry that the site does not contain explicit references to the research materials mentioned in your lectures.

  • Do baboons know that sex leads to babies? That seems to be what he is saying, but I didn't think they realized that. And I certainly didn't think fish did. What else could be going on here?

  • 28:43 … irrefutable, statistically totally reliable …

  • Who else thought about showing this to their third cousin?

    No one… ?
    Maybe I should think of something else entirely then…

  • Another thing about third cousin distance attraction, he made a graph where third cousin was the peak and it descended evenly on either side, does that mean a fifth cousin, or so, distance is about as attractive as a very distantly related person (different continent, etc.)?

    I just did the math (hopefully correctly) and got that third cousins are approximately 0.390625 percent related; how does that have an effect on attraction when it is genetically so small and why would that amount give an inclusive fitness? I have to assume that most times in evolutionary history third cousins have more relatives in common that one great grandparent or does the study account for that and mark them as closer than third cousins?

  • He said that people found the smells of others at a third cousin distance most attractive, but how do we know if that attraction is DNA genetic or more like the grandma effect where it is passed down environmentally? Were the people that they were smelling actually third cousins or did they have some percentage genetic similarity in random areas; i think he used the word histocompatibility at some point?

  • @recognizing by smelling (1:12:00) : in trance- therapy i made the repeated experience, that fathers, suffering from an kind of "cold" relationship and a lot of conflicts with their children, often had a very vague feeling, that the child have had a "wrong kind of smelling" ..

  • As far as I know, chutes/snakes and ladders, does not involve any skill whatsoever. It's completely random who wins. There is only one choice given to a player and that is that they may roll again after rolling a 6, but unless we know the exact rules of the game as played in the study, how can we tell if the information is valuable?

  • I've had to explain this so many times at university – I got good at it. If you understand the basic explanation below, it will fall into place thereafter…


    Just remember that HERITABILITY is about POSSIBLE DIFFERENCE in GENES in A POPULATION (more than one person) – if the gene is the same for everyone then it is not heritable. "Inherited" is not the same as "heritable."

    INHERITED = genetic similarity in population.
    HERITABLE = genetic difference in population.

    1.  If you share a trait with both your parents – its the same for you all – then it is not heritable. 
    You INHERIT all of your genes from your parents, but heritability is about difference, not sameness.
    2. The traits that make you different from at least one / either one of your parents are heritable.

    EYES: I inherited the genes for eyes from both my parents – both my parents have eyes
    — rule [1] >> NOT HERITABLE. 

    EYE COLOUR: My mum has blue eyes, my dad green eyes – I have green eyes, which is different from my mum
    — Rule [2] >> HERITABLE.

    EYE COLOUR #2: My dog has brown eyes – her mother and father both have brown eyes – in fact her whole breed has only brown eyes
    Since her whole lineage has nothing but brown eyes, there is no chance of DIFFERENCE so there's no HERITABILITY in this POPULATION.

    HEIGHT: Mum is 5 foot, dad is 6 foot – they have identical (monozygotic) twins – they feed twin A a low calorie diet, and twin B a high-calorie diet. Twin A reaches 4 foot, and twin B reaches 6 foot.
    — For both twins, Rule 2 applies >> HERITABLE.

    But notice that twin A is 2 feet shorter than twin B, even though they are 100% genetically identical. So, taking the twins as a population on their own and comparing their difference in height, one has to conclude that environment (diet) plays a role in height too, not just heritability/genes.

    The question "Is it heritable?", has nothing to do with the question "Is it environmental?" – they are separate questions. Once you solve the heritable / non-heritable question, then secondly, you have to solve the heritable / environmental question.

    Heritability is about genes, not environment, but both can/might play a part in any difference. As in the twins – height is both heritable and environmental: Short people have short kids, tall people have tall kids, but what you feed them can affect how tall they get. But, for some differences there is no environmental effect: Such as eye colour – no environmental factor like early separation from mother will change your eye colour – if you have the genes for brown eyes they'll be brown whether you live in desert or on a desert island.

  • 2.3 IQ points is not a small difference. It will make a big difference at the tails of the distribution.

  • How about babies crying interrupting concentration, combined with sleep interruption affecting the first born. What happens to the mothers IQ. What if she's blonde?

  • what if the genes of my natural uncle match mine to where we easy learn to speak in harmony based on having the same amount of similar genes…what if ecological factors can create an environment that does the same thing among friend niggas?

  • the Nepalese were better nurished and had traditional building blocks, folklore, exploration derivatives, and elevated land that hinders early development to day dream

  • I'm so happy there are so many Sapolsky videos available. I would love to actually take a class and yet, I feel privileged just to have access to it. It's almost like taking the class.

  • Why do people do things like at 20:50? You're talking to someone, and they're acting like they think they're a chimpanzee swinging from a tree. Or they're bouncing their left leg up and down rhythmically as you're conversing with them. It would never occur to me to act like a monkey during a lecture, or in a meeting, or at lunch. And yet people (mostly guys) do this kind of thing. Why?

  • 09:30 The Wikipedia article on Chutes and Ladders (which redirects to the British board game "Snakes and Ladders", which in turn was adapted from the ancient Indian game "Moksha Patam") is worth a read.

  • Love the lectures. But why does Sapolsky show up for class so often in sopping wet tennis shoes? The "squish squish" sound as he paces is distracting.

  • Question: When Robert talked about bees recounting high value forage in the middle of the lake to the other bees, and then losing credibility because the other bees are capable of distinguishing implausible information… It seemed as this was light hearted anthropomorphism, But,would the ability of a individual bee to have and then lose credibiiity be a demonstration of theory of mind? 'Others knowing that' such a  bee gives implausible information…?

  • 9:30 KoRn – Shoots and Ladders

  • yeeaah there are a ton of studies out there that must have been the result of having an idea/ hypothesis that ended up not rendering anything, and selectively stating results. maybe even manipulating the data, if your difference isn't statistically significant and someone tries to reproduce it, well, built in disclaimer. i had to read so many absolutely ridiculous "scientific" papers in college that apparently fooled professors by using the ludicrously wordy and word droppy language typical of those things

  • "We're not a whole lot fancier than hamsters." …love it 🙂

  • i noticed it and thought i would point it out… it doesn't hurt anything and it was amusing to me. could yall not read the sarcasm in my comment? he made the assumption I was an idiot

  • Troll, who exactly did you think I insulted? I expressed surprised at the almost 100% market share that Apple enjoys in that classroom. You, on the other hand, seem to delight in insulting people needlessly.

  • Free education on youtube, im going to insult one of the humans that help make this possible a camera monkey. "Pointing out the obvious brings me joy"

  • you know i was trolling for your comment

  • 30:00 begins kinship/recognizing relatives

  • 42:00 he said how you would design this… that means intelligent design right?

Leave a Reply

Your email address will not be published. Required fields are marked *