The Evolution of Cooperation and the Paradox of Altruism

okay good evening can you all hear me we have a complicated double micing system can you hear me at the back John are you okay yes good okay great welcome I'm very glad to be able to to be the first to welcome you tonight there will be others saying welcomes as well my name is Barbara Altman and I'm the director of the Oregon Humanity Center here on campus this is the second in a series of six events celebrating the Bison Centennial of Charles Darwin and the cesa Centennial of his Landmark Book On the Origin of Species as you may have noticed Darwin is getting a lot of press at the moment his birthday is in fact on Thursday this week I believe and he is the cover boy of the science section of today's New York Times magazine or not the not the magazine but the journal so if you want more when you go home look up the times and and uh read what they have to say our series includes four faculty members from the U ofo we began with Patrick Phillips in January and had an overflow uh overflow crowd for him as well and he talked about the sex life of neemod so it was no [Laughter] surprise uh this evening you will hear Professor Holmes and then we'll have Joe Thornton in March and Francis white in April May will bring two outside speakers the first of those is sha Carol from the University of Wisconsin who's coming coming on May the 4th as the Oregon Humanities Center 2008 2009 Robert D Clark lecturer and then closing the series will be Kenneth Miller from Brown University who will deliver the criticos lecture for the Oregon humity Center in this series on May 27th so we had January February March April and then two in May please come to as many of them as you can possibly make I'll be brief because I'm just the first of two warm-up acts the Oregon uh Humanity Center my unit is one of the co-sponsors of this event but there are many others and that's testimony to the breadth of Darwin's influence the other sponsors are the center for Ecology and evolutionary biology The Institute of molecular biology The Institute of Neuroscience the museum of natural and cultural history the department of biology and the College of Arts and Sciences we're especially pleased at the Oregon Humanity Center to be working on this series and a number of other projects with Natural Sciences this year I want to acknowledge our associate director Julia Hayden who enthusiastically leapt at the chance to collaborate on this series when the idea came up I also want to thank the other members of the Oregon Humanity Center for all their hard work including the Striking poster that you might have seen those people are Melissa gustofson Peg gearheart Dylan brag and noal aloy do have a look at the poster which is all over campus and a lot of places around town if you have a minute make note of the dates of the other offerings but if you don't have that at hand you can always find all the details of the other events on the website for the Oregon Humanity Center so come to the uo website and then go to Oregon Humanity Center to find all the dates and times and names for now and without further Ado Let's Get Closer to the heart of the matter I'm going to pass off to our next introducer our speaker for the evening will be presented by Scott colrain dean of the College of Arts and Sciences [Applause] Scott well good evening and uh thank you uh I'm honored from the College of Arts and Sciences uh to be a sponsor of this event and it is my honor to welcome um Warren Holmes Warren Holmes was born in and grew up in the Northwest he received his undergraduate degree in chemistry from mamit University in 1970 and his PhD in 1979 from the animal behavior program in the psychology department at the University of Washington we won't hold that against him subsequently he spent 23 years as a faculty member in the psychology department at the University of Michigan where he was one of the founding members of the evolution and human behavior program each summer however he left the flat lands of the Midwest for the mountains of the west where he did his fieldwork on the development and function of kin recognition and nepotism in ground dwelling squirrels which he assures me are much more interesting than tree squirrels Spending Time in the West each summer also meant that after his field season ended he could indulge in his true passion which was wind surfing is wind surfing in the Columbia River Gorge Warren retired as an Emeritus Professor uh and faculty member from the University of Michigan in 2002 and he came to the University of Oregon where he is a professor of biology and psychology and he's been here since 2002 Warren Holmes is the author of 40 scientific journal articles and chapters including uh a publication in the prestigious journal Nature and I counted from his CV a remarkable dozen articles 12 in the journal animal behavior which is quite an accomplishment at Oregon he teaches courses in animal behavior and in evolutionary psychology and is a senior researcher in The Institute of cognitive and decision Sciences tonight he will be describing some of his own research and discussing how a darwinian perspective can help us better understand cooperation and altruism in all organisms please join me in welcoming Warren [Applause] hmes [Music] want what kind of high sign will I get that word um I will wait for Julia to let me know okay wonderful uh thank you very much Dean colron for that uh introduction and it's a delight to be here um I've been asked to do what faculty members can easily do sort of talk and spin his wheels for a few moments apparently there's an audio problem with the feed upstairs so I could regil you with ground squirrel stories but you really need pictures in order to uh benefit uh from that so we'll have to wait just a couple of minutes I guess I should ask the audience in here and there are two different mics can you hear me is everybody happy with uh with the audio okay now if I were to ask that upstairs apparently the answer is no so I will just uh continue to walk back and forth here um well I can do something since it's not uh very substantive so I'm going to go ahead and tell a little story and then we'll get on um mention was made of uh Darwin in the uh science section of the New York Times uh today indeed there were a number of articles I encourage you to read uh Nicholas Wade's uh article from that I have uh taken some texts that I would like to read and direct to uh the dean and any other high-placed administrators who might be here so reading from uh Wade's article how did Darwin come to be so in advance of his time why were biologists so slow to understand that Darwin had provided the correct answer on so many Central issues one of Darwin's advantages was that he did not have to write Grant proposals or or publish 15 articles a year he thought deeply about every detail of his theory for more than 20 years before publishing On the Origin of Species in 1859 um I hope that the dean and other administrators will agree that Darwin's model for scholarship is one worth pursuing and I did want to wrap that up with yes we can I hope all right [Music] apparently come on now it's gone to sleep on me I can't find is it right there there we go all right in 1859 when Darwin published his origin he did two things that inevitably altered the way many of us view the living world first he documented with one fact after another that Evolution had occurred species came and went descent with modification was real to use Darwin's term second and more importantly he gave us a mechanism or process by which descent with modification could occur that mechanism or process natural selection that is Darwin's true genius each of the three sets of organisms that you see in this slide provided challenges for Darwin's proposed mechanism because these animals along with many others exhibit striking displays of cooperation and even altruism in some instances as far as I know um Darwin knew nothing about ground squirrels or Mir cats uh but he did know that some of their behaviors and certainly some of the ways in which ants and other social insects behaved did not fit well with his theory and he worked very hard to explain them what is striking is that many of our explanations today were there in 1859 so during the next hour uh or so I will present some of Darwin's explanations for cooperation and altruism and also offer more recent explanations that often began with his book in 1859 let me see if I can help you understand a little bit about why for evolutionary biologists cooperation and altruism are potentially problematic and I want to do so by introducing Andrew Carnegie and the uh hero heroic award uh that he instituted I think in the early 1900s a quote I do not expect to stimulate or create heroism by this fund but I do believe that the hero and those dependent on him should not suffer financially good thoughts from not necessarily the most heroic or altruistic man ever un interesting caveat the nepotism caveat ineligible recipients if you go to the website you will discover persons not eligible for the reward members of the immediate family a puzzle why exclude family members well I hope that by the end of the talk tonight you will understand why Carnegie excluded family members even if he didn't know why hopefully we all will so my conceptual framework is one that you don't necessarily routinely work in so for the next couple of slides I want to introduce my concept ctual framework those students who are taking my evolutionary site class uh right now who probably should be studying for the exam on Thursday we'll gain a little bit by looking at this one more time how does animal a exhibit Behavior x a very general question there are two types of proximate explanations immediate causation things like hormones and behavior learning and behavior socialization and behavior the development of behavior refers to changes as a result of specific experience during the lifetime of the individual and we're all used to asking questions about immediate causation and development and answering them in that framework there is another way of thinking about why animal a exhibits Behavior X ultimate explanations evolutionary history or philogyny one way to explain behavior is to refer to the ancestral past we behave like primates because we are primates and primates behave in certain ways another way of explaining at the ultimate level get that up there there we go the functional value of a behavior its adaptive significance how does it contribute to survival and ultimately to reproductive success so proximate and ultimate refer to a temporal Dimension proximate is short-term explanations within individual lifetimes ultimate on the other hand refers to longterm deep history explanations explanations across Generations not ultimate in the the Beall and IND all sense but in the sense of time removed let me continue with my framework by introducing some terms in if you look hard at this I was so delighted when I found this um Alice is talking to Humpty Dumpty who looks suspiciously like Carl Rove and if you look real hard up there you'll see the word truth when I use the word Humpty Dumpty said it means just what I choose it to mean nothing more nor less so let's talk about some of the important terms that I want to use tonight cooperation and altruism cooperation in approximate framework Behavior by one individual that's intended to benefit another and certainly climbing partners are individuals who intend to benefit one another to help each other there is intention and motivation in their behavior there's another way to think about cooperation at the ultimate level of analysis Behavior by a donor that increases the reproductive success of a recipient the focus is no longer on intent and motives it's clearly and purely on the reproductive consequences of the behavior the donors pays a reproductive price the recipient gains a benefit and a picture of sisters one an older sister babysitting another fits nicely into that category we need to talk about another term altruism if you thought cooperation was slippery I suspect all of us would agree that Mother Teresa was an altruist I don't know that we would agree on much more than that so let me be clear on how I'm going to use uh this term Al altruism in the proximate sense a selfless desire to help others that won't be my focus tonight rather altruism at the ultimate level of analysis a behavior that reduces the fitness of a donor and increases the fitness of a recipient and I highlight donor and a recipient because I'll use those terms over and over Fitness here refers to relative reproductive success the number of babies an individual produces and Rears successfully over his or her lifetime the altruism Paradox how can selection produce a behavior that lowers individual Fitness and the Exemplar for altruism is this female honeybee the quintessential altruist um I suspect all of us well especially the males have had intimate experience because as a kid we tried to trap the bee in the jar what she does besides cause enormous pain is give her life in defense of the hive moreover this sting has been evolutionarily modified it evolved originally as an ovipositor an organ through which a female would deposit eggs it was modified over time until it had barbs on it so now when this female injects this it eviscerates her in defense of her Hive Darwin was aware of this and perplexed by it so what I want to do having laid out a framework is now try and run through three functional explanations for cooperation and altruism and when I say run I don't literally mean run that's the rest of the the evening first up altruism and group selection this is the way we wish the world was group selection groups of altruists will out reproduce groups of egoists the notion of group selection is that individual group members will restrain their reproductive output for the group good so in order to over uh in order to avoid overexploiting a resource individuals will hold back because that's beneficial for the group In Darwin's Second Great book um sexual selection The Descent of Man he wrote A Tribe including many members who sacrific themselves for the common good would be victorious over most other tribes on the surface of it group selection seems to make evolutionary sense but as I said Darwin was ahead of his time there's a problem which he was very well well aware of he who is ready to sacrifice his his life would leave no Offspring to inherit his Noble nature so let's look at group selection the old and then the new wi Edwards published a book in 1962 which served an important purpose despite the fact that most people would say he got it wrong and it was a big book what he did is lay out very clearly what a number of biologists had been thinking a model called group selection the notice of individual restraint for the group's good so traits would evolve that benefited the group even if they harmed the individual but what about the Eric cartans of the world what about cheaters or free riters cheaters or free writers in a group of altruists are individuals who benefit from everybody else's altruism but don't occur incur a cost by behaving altruistically themselves so Darwin was aware in the last quote and certainly theorists today are aware there's a problem and it is this cheater or free writer problem things have changed since when Edwards published his book there is now a new kind of group selection referred to in different terms often the most common multi-level selection Theory the latest in group selection logic in multi-level selection Theory the comparison is on the power of selection within the group versus between the group and depending [Music] on that's that's exactly the way I feel about the old and the new group selection and I'm not the only one despite what some recent visitors to town have said kin selection that you'll hear more about in a while and new group selection are just different ways of conceptualizing the same evolutionary process both empiricists and population geneticists who develop models would agree with that assertion and the airist would say and it's a lot easier to collect data to test kin selection hypotheses than group selection hypothesis Foster Ed Al say kin selection is the key to altruism in a very nice article on the usocial insects I'm not going to say very much more at all about group selection other than if it is a significant evolutionary force it may well be most significant for us and some other primates let's move on though altruism and reciprocity in 1971 Robert triers published his paper on reciprocity Mutual exchange of costly but helpful acts and I think climbing partners are a great example of reciprocity because who's ever on Bay now is going to be holding the Rope for his or her climbing partner later on Mutual exchange of costly it takes some effort but helpful acts triers pointed out that in order for reciprocity to explain Cooper and altruism at least three criteria had to be satisfied repeated donor recipient interactions if I scratch your back today you better be around to scratch my back tomorrow low cost benefit ratio if I'm going to do something nice to you there's no guarantee you're going to be nice back to me so maybe just a small nicity rather than a large one until we get going in a reciprocal interaction finally it's important to be able to recognize and recall donors and cheaters this combination apparently has made reciprocal altruism in non-human animals problematic Stevenson Hower in a nice review article a few years ago wrote despite immense theoretical interest little empirical evidence substantiates the biological importance of reciprocal altruism in non-human animals a few examples but not very many many and given that there aren't very many I am simply going to move on to the third functional explanation for cooperation and altruism and this is the one that I want to spend a fair bit of time on altruism and Inclusive fitness WD Hamilton in 1964 published a couple of papers from his dissertation for those of you graduate students who are working on dissertations this is not something that you want to hear about because many people would say that Hamilton's 1964 paper was the most or at least among the most significant revisions of Darwin's theory ever so if you want to go for it do so um you have a tough row to Hope what Hamilton pointed out is that if we think about selection designing organisms to transmit genes from one generation to the next organisms can do this in two fashions in a direct and an indirect fashion first of all ego not the clinicians Freudian ego but our focal individual ego can rear its own offspring and in so doing influence ego's Direct Fitness ego can also influence Gene transmission indirectly by helping ego's non descendant or collateral relatives in their reproductive efforts so for example helping a sibling is a way of increasing the number of nieces and nephews this isn't the mathematical equation that Hamilton derived in his population genetics model but it does a decent job of uh portraying this general idea of kin selection so what I'm intending to show here is that Inclusive fitness has two components direct and indirect the direct n zero is simply the number of offspring that ego rears successfully on as a result of uh his own effort the indirect component says that non-descendants who are reared as a result of ego's help also influence ego's Inclusive fitness and this term right here R refers to looking at the bottom genes shared due to recent common ancestry some relatives are better vehicles for indirectly transmitting genes than others close relatives are better than distant relatives are gives us a measure of closeness and together direct and indirect selection are often referred to as kin selection so a drawing to make sure we're all clear on this or everything else I say isn't going to make a whole lot of sense and I played around a lot with this particular drawing got some very helpful feedback from members of The Evolution focus group when I did a practice talk last week I'll be interested to hear from you whether this is better or not we'll see so what I want to do is explain genes identical by descent and helping so to start up here A and B are siblings as a result of that we know that they share on average 50% of their genes in common nope the way things are set up here a is going to help B rear some of be's offspring that is a is going to be taking care of nieces and nephews that help is portrayed here is a who provides some money to sibling B which allows the purchase of food or medicine or whatever and as a result B produces young now if we're focused on ego a note ego can transmit genes directly via his offspring A1 A2 A3 and A4 if you look at a a total darkened um Square what I'm trying to show you is that each one of his offspring share half of his genes in common of your genes are from Mom half are from Dad I'm just showing one parent here notice also that b looks a little bit like a in terms of the way I have B colored exactly half likee because the degree of relatedness is 0.5 look at The Offspring of b b is A's sibling these from A's point of view are nieces and nephews they share a quarter of their genes in common with individual a so when a rears its own offspring a is transmitting genes when a helps its sibling B A is transmitting genes now where things get tricky here is I have suggested that indirectly a is responsible for B1 through B4 there's a problem here and Hamilton was very well aware of it it is only the case that you would include all four of these nieces and nephews if they were due to A's assistance if a provided enough money only for B1 to survive then that's the only non-direct or indirect connection to a that didn't make sense don't worry a whole lot about it um we will not be visiting that again using this logic let's move on to altruism and Hamilton's rule Hamilton's rule is very straightforward and that's extremely fortunate because for those of us who back in graduate school Wed through his 1964 paper it was a real Wade and at the end it was thrilling to come down with a simple equation like this R * B minus C must be greater than zero if that is the case altruism can evolve so here's WD Hamilton here is a quintessential problem in altruism that Darwin was very aware of these suicidal females Hamilton argued that behavior makes sense if we acknowledge that R refers to genes identical by descent between the donor and the recipient B is the Direct Fitness cost excuse me the best I'm looking at that and thought I had a typo I it was a spoko Direct Fitness benefit to the recipient in C is the Direct Fitness cost to the donor where in the long run benefit and cost are measured in terms of Direct Fitness Direct Fitness increased or Direct Fitness decreased here's a quote from JBS halane a British uh biologist well before Hamilton's time who among a couple three others sort of Saw Hamilton's logic before he presented it halane is reputed to have said I would gladly give my life for three of my brothers PA D is 100% related to himself half related to a brother 3 * .5 is 1.5 which is greater thanane is related to himself there go the logic or nine of my cousins cousins 1/8 of their genes identical by descent nine of them would be 98 I'll leave you to do the math but it makes evolutionary sense so this is the general prediction that falls out of Hamilton's equation and thinking about Inclusive fitness and altruism the general prediction the one that you see over and over in the textbooks the social behavior of a species evolves in such a way that the individual will seem to Value his neighbor's Fitness against his own according to the coefficients of relationship appropriate to that situation remember coefficients of relationship mean measure genes identical by descent and a very important term or word in this is right there SE remember Hamilton is giving us a functional or ultimate level explanation he is not too concerned about the proximate the motives the the short-term thinking the cognition that goes U along with this kind of behavior he is predicting individuals will act as though they understand Inclusive fitness logic takes us to ground squirrel alarm calls I said with my opening slide that Darwin didn't know about ground squirrels or Mir cats that said I'm not quite sure that what I have highlighted or embolden here is fair but his quote the most common service which the higher animals perform to each other is the warning of danger and given that I'm going to talk about ground squirrel alarm calls as uh danger signals clearly Darwin thought of them as higher animals even if he wasn't particularly aware of them at least they have fur compared to Patrick's naked worms which so before regaling you with stories of alarm calls and nepotism and ground squirrels what I want to do is try and present an ecological context for you to interpret what I have to say so I need to tell you about Bing's ground squirrel's uh Natural History um belling's ground squirrels are Sid rodents that's one of those terms you can write down and hope it appears in a crossword puzzle or whatever um the cids are the marmots uh and prairie dogs and ground dwelling squirrels which truly are a lot cooler than tree squirrels tree squirrels are asocial except on campus where we feed them um ground dwelling squirrels there are something like 20 or 23 species in North America most of them are group living so if you're interested in social behavior and social relationships tree squirrels make no sense ground squirrels make all the sense in the world another way I often describe the difference between these two taxa tree squirrels are cats ground squirrels are dogs in terms of Social and asocial um adults weigh about a little over half a pound 275 grams this particular species Belding ground squirrels are found in Alpine and subalpine Meadows in California and Oregon they are obligate hibernators they spend seven or eight months a year in in a near-death State alone in an underground burrow females produce one lit a year during a single three-hour receptive period you see the headache joke that you're not not coming okay 3 hours but they do make up for the short period of time because they mate with multiple males up to seven males in that period of time female typically will produce a litter of five Young terms of rearing ecology how do young grow up and this is important for the story that we'll unfold in a moment females construct an underground burrow that I will refer to as the natal burrow a few feet underground and maybe a 20 or 25 foot uh tunnel back to it female a female will give birth in that underground burrow and her young will remain there for the first 25 days of their life their social world is very limited to their siblings and their mom because their only parental care that they experience is is from Mom male ground squirrels are classic mamalian males they mate and run we humans are remarkable and very different in that regard that's one of the things that Darwin didn't talk about and it surprises me that he didn't given that he addressed so many other perplexing features paternal behavior in males is a mamalian anomaly and that's intriguing so only care for Mom besides providing nutrients and warmth to these underground babies moms are territorial in defending a small area around their natal burrow and they will do that because other adults both males and females will come in and attempt to commit infanticide indeed one of the most significant forms of U pre-emergence mortality is infanticide by adults dispersal by sex occurs differentially and this has important consequences at the end of a ground squirrel's first summer at the end of its juvenile summer the females will stay home set up their own burrow within 20 or 30 m of Mom's burrow the males on the other hand will disperse four or 500 meters the result of this is that females live near close genetic relatives and males do not think about nepotism the other point to make about females because overwinter mortality is high some 60% of juveniles fail to survive that first uh period of hibernation that means that while a female will often live near a close female relative another neighbor may not be a close female relative because some of those relatives died during the winter are females hamiltonian nepus well there are two different things at least that females do one I mentioned territoriality and infanticide I'm not going to talk anymore uh about that what I do want to do is talk about alarm calls and predators and attempt to determine whether females act as though they read that 1964 paper act as though so let's talk about ground squirrel alarm calls is this an example of kin selected altruism uh let me introduce to you not a ground squirrel but Mr ground squirrel uh Paul Sherman uh behavioral ecologist at Cornell University Paul and I collaborated for several years uh on our work on ground squirrels uh he was particularly interested in alarm calls I was particularly interested in kin recognition you're going to get to hear about both so some background on ground squirrels um these little guys give two types of calls in response to a terrestrial Predator a single high note Trill guess what's going to maybe come and in respon respon to an aerial Predator if you heard that and you were a ground squirrel you would look around not up or excuse me you would look up if you heard that call you would run and you may call as well the benefit these calls clearly alert vulnerable others when a ground squirrel gives an alarm call if you'd been ground squirrels even given my crummy imitation you would have been up and looking like this where is the danger so it's clear that individuals are alerted to the presence of danger that they might not have known about what about the cost remember an altruistic act benefits the recipient and costs the donor there is an increased chance of death why well it's pretty straightforward here's this clown here I am thanks for the help notice this is the terrestrial aerial Predators hunt with their eyes not so much with their ears the terrestrial Predators eyes matter but so do ears so calling to a terrestrial Predator is definitely not a good idea in fact instances of predation are rare but when they do occur collars are taken twice as often as non-c callar it is very expensive to say here I am much better to be quiet this raises the question is this risk incurred in order to warn kin and if so which can so what I want to do is look at in a couple of data slides now first of all who gives alarm calls and then secondly who gives alarm calls so these are data on the Y AIS the frequency of callers and on the horizontal axis various age and sex classes so these are data from the first squirrel to give an alarm call remember other squirrels will call in response so it's the first one who presumably is at at risk in response to a terrestrial Predator now to make sense out of the data I have to explain expected by chance and observed in the field observed is easy that's simply what you see you count them what do I mean or what did Sherman mean expected by chance expected by chance means calling in proportion to the number of individuals of a particular type that are present so for instance if there were 20 males and 10 females present when the Predator appears you would expect twice as many male calls to female calls if there were 10 males and 10 females you would expect 10 male calls to 10 female calls okay so let's look at these various age sex classes right away we see that adult females are calling frequently in fact two to two and a half times more often than expected by chance they're really engaging in Risky Behavior sensible males sensible in appr proximate sense not in an ultimate sense necessarily although I think there is Ultimate logic in what they're doing notice for adult males they're capable of calling but they call much less often than you would expect them to based on their numbers alone and if we look at the rest of the age in sex classes yearling females yearling males juvenile females juvenile males remember the juveniles are the young of the year the yearlings guess how old they are and adults are two years uh and older well calling by chance for all age classes other than adult males and adult females let's look more carefully at adult females we see some evidence consistent with a hamiltonian argument for nepotism remember males don't live near their relatives so calling only warns competitors they're silent makes functional sense females on the other hand do live near relatives so calling makes some sense how fine-tuned is this sense here Sherman and his field uh workers and there were a good 20 of them over uh these data are over an 8-year period so that's a it's probably 3,500 hours of direct observation and and that doesn't include driving to and from and all that these people know their animals if we look just at females again on the Y AIS the frequency of cers on the horizontal axis various kinds of kin alive in the population so so the same expected and observed as before if we look at these females these are females whose only living relatives in the population are either daughters or granddaughters they're calling significantly more often than they would by chance alone similarly if a female's only living relative is her mother or her sister she calls more often than she would by chance alone however if the only living relative is a niece or a cousin calling by chance so females with close kin alive call most often so to summarize nepotism by sex remember only females call females live near relatives males don't live near relatives given that calling is costly it would make no darwinian sense for males to call it may make darwinian sense functional sense for females to call and they do Sherman's second Point nepotism among females is limited females will call if they have a mom a daughter a sister Andor a granddaughter present but if their only living relative in the population is a niece or a cousin or several nieces or several cousins they do not call how do we account for that well one possibility is that ground squirrels and this is the one that Sherman suggests that ground squirrels have not evolved the ability to recognize uh nieces or cousins if you can't recognize them then you don't know that they are alive in the population we now know that the recognition problem is not the correct answer another possibility is on the benefit and cost side we don't know about that and so I'm just going to move on I have some thoughts and if you have questions I'll be glad to share the thoughts Hamilton's rule I put the question mark here not to question his rule but to question whether ground squirrels are acting as if they read the rule the answer is well maybe maybe not up here consistent evidence but I do want to make an important Point remember Hamilton said Inclusive fitness has these two components direct and indirect the hooker with the indirect component is it's always multiplied by this fraction Gene shared in common in general it is going to contribute less to Inclusive fitness than Direct Fitness another way to say that is a functional explanation would go something like organisms are designed to care more to be concerned more about their Direct Fitness than their indirect Fitness apparently ground squirrels got that message because look what happens when Sherman reports his data on response to Aerial Predators remember these predators don't hunt with their ears they hunt with their eyes what would a smart ground squirrel do if it sees a predator and wants to avoid being a meal it would in effect say take somebody else anybody but me and one way that I'm going to help you is by giving a call that causes everyone around me to run so Sherman argues in response to Aerial Predators what we see is self-preservation a direct fit explanation rather than an Inclusive fitness direct plus indirect well I mentioned something a moment ago that I want to look at more directly perhaps this not to nieces or cousins had something to do with recognition so let's talk about kin recognition Hamilton's General prediction is that cooperation via nepotism will evolve nepotism favoring genetic relatives over non-relatives requires an ability to recognize Ken you might think a ground squirrel recognize Ken if you were thinking that way you are making the same sort you were working in the same proximate I was going to say you were making a mistake but there's another way to phrase it you were working in that proximate framework the same one that a well-known Anthropologist was in and he should have known better when he said of the peoples that he was studying Hamilton made no sense for these people because these people could do numbers whole numbers up to four they didn't understand fractions at all that's one of those it's a great quote and we love it because it allows us to make this very important Point here about kin recognition kin recognition doesn't mean analyzing DNA kin recognition refers to differential treatment of kin based on correlates of genetic relatedness not of genes identical by descent but things that correlate with genan identical by descent you can't wait to find out what they are well let's do it right now how do you know who your siblings are the first answer that comes to most people is oh the jerks that I grew up with uh maybe I that's not the case I I'm one of three brothers fortunately I'm the oldest the other two were occasionally jerks I know they're my sibs cuz grew up with and that's the better way to do it corelates of genetic relatedness family resemblance everyone has heard something like you at one point anyhow look just like your uncle Mary or your um no ad it would be your Aunt Mary or your Uncle Bill relatives are more phenotypically similar than non-relatives so phenotype matching comparing some image of kin with this unknown individual and ask how similar is the phenotypic resemblance by phenotype I simply mean those aspects uh of an individual that you can see smell hear the external uh manifestation of the genotype if you will another correlate and one that I want to talk about prior Association or familiarity in my little drawing here or picture here's a litter of new bone ground squirrels here is that same litter having emerged above ground remember I said in the case of Belding ground squirrels those little guys are going to spend 25 days together in Intimate Association if when they come above ground they distinguish former rearing mates from non- former rearing mates familiar from unfamiliar they are acting as though they have done a DNA analysis and identified siblings versus non- siblings how could you go about testing prior Association you can phenotype way too complicated for me to try and make sense out of it so let's talk about prior Association which is probably one of the most common kin recognition mechanisms um in uh the animal world experimentally there's a very straightforward way to test this mechanism you can mix up kinship and familiarity if you're working with ground squirrels and they cooperate so here's a mom that has four babies and here's another mom the same morning that has four babies you can take these two and Foster them to her these two and Foster them to her so you now have some individuals who are growing up together that are siblings they share genes identical by descent you also have individuals who are not growing up who are growing up together but do not share genes in common as long as these two moms are not relatives when you do your cross fostering you have some genes in common and others without genes in common after doing this switch you can let the young grow up and then do a paired encounter test take pairs of ground squirrels put them in a small neutral enclosure and watch them for a period of once you figure it out it takes uh 15 minutes of observations and you record the frequency of agonistic behavior agonism is a combination of offensive and defensive aggression so paw swipes bared teeth growls which I won't even try and do a bite I definitely won't try and do a bite those are examples of agonism when we did that in the laboratory back in Michigan we found a very clear result familiarity mediates sibling recognition in order to make the outcome clear the light bars are individuals that were reared together regardless of genetic relatedness the dark ones are individuals who are reared apart regardless of relatedness what you see the together pairs are noticeably significantly less agonistic than the the apart pairs a clear familiarity effect remember burrow sharing correlates with relatedness perfectly acceptable correlate to identify siblings in the case of ground squirrels turns out that that's not completely true and I'm not going to go down that path unless somebody asks about it and I gave you a hint remember those over sexed females siblings reared apart this the sibs reared apart do look to be a little bit less aggressive than the non-ibs reared apart and in fact when you do the statistical test this is one of those just Killers significant at the 0.07 level not the magic 05 what does it mean well at the very least it means and given the natural history of ground squirrels let's look at females in particular so here the sibs are the open bars the non-ibs are the hatched bars again mean agonism and male female Pairs and male male pairs no difference as an effect of relatedness however look at what happens when we turn to the females sisters are significantly less aggressive than non-s sisters sisters act as though even reared apart since birth they can still recognize an individual with whom they share on average 50% of their geneses in common how they do it is a whole another story in terms of sensory system I should have mentioned this earlier it's the nose but there's more to it uh than that let's move on the development of nepotism first of all I want to make an important point at least to me kin recognition is not the same thing as nepotism nepotism Fitness enhancing Aid to relatives so for example alarm calls might be an example of nepotism here is a delightful poster of lion nepotism the question that I want to address since I'm interested in development in a functional framework how do we get from non- nepotistic juveniles remember they weren't alarm calling to nepotistic adults one of the things that ground squirrels do a lot of is social play I wondered based on lots of time in the field whether the play partner references that juveniles displayed might lay the developmental foundation for adult social relationships for adult nepotism so here are a couple of ground squirrels playing together um and what I want to do now is I don't know maybe I'm just presenting you an excuse for why I wanted to spend a few thousand hours watching it's a lot of fun that's the reason so let's talk about assessing social preferences um um for 12 or so years um graduate students undergraduates and I have worked at a field station uh in the Eastern Sierra in California near Mammoth Lakes a wonderful place to spend uh part of the summer tell the wind starts blowing in The Gorge so at the Sierra Nevada aquatic uh research laboratory near Mammoth Lakes it's about 40 miles south of uh yede at snarl we built some large outdoor enclosures and here is one of them uh this enclosure is 30 ft this way by 30 ft that way and if you look at those black triangles they represent Burrows we put Burrows with PVC pipe and an underground uh Nest box four of them so we could put litters of ground squirrels into these enclosures what you see here are four juveniles that have come above ground uh from their underground burrow and are sitting on their porch so within an enclosure there could be four lit that's 16 uh juveniles and four adult moms and we would watch play right here or like that so for the first 10 to 12 Days After young come above ground my assistants and I would each day watch these lady clarol fur dye marked all ground squirrels look alike to me uh to all of us I suspect so fery allows us to recognize individuals we recorded the frequency of social play as a function of a number of things so siblings are preferred play Partners that's the punch line here the mean frequency of play on the vertical axis and on the horizontal axis three different groups captive reared means young whose moms were pregnant when we brought them into the laboratory cross fostered them at Birth and then did the observations um in the enclosure field reared were young who were reared by their moms in the field on the day they came above ground we were right there to live trap the young bring them into the enclosure watch them for 10 days 2 weeks and then put them back where we got them and reducing from four to just uh 2 lit to make sure there wasn't a density problem in all instances what you see is siblings are preferred play Partners the frequency of play is significantly greater for siblings than for non-s siblings keep in mind this is quite dramatic because for one individual there are only three sibling play Partners there are 12 nons so these preferences are quite robust given that by chance alone they're going to bump into non-ibs much more often than siblings one of the interesting things we found about these preferences is that moms have something to do with them mom's presence influences Social Development here what I show is the result of just one group when juveniles were put into the enclosure at their natal emergence age without moms and observe for a period of 10 days 2 weeks there now is no significant sibling preference what is it that moms do well we still don't know for sure but one of the things that seems to matter is that the absence of moms influences sleeping burrow use so here on the Y AIS is the percent of individuals who are sleeping with a sib in one group when moms are present over the first seven days in the closure siblings sleep together in their common burrow every night however if moms are not present when you put them in they're the kids sleep together because they don't have a choice but look what happens on the second night and subsequent nights in the absence of moms sibs are no longer associating at night suggesting that something about associating at night is important to these social preferences the retention of social preferences we're still trying to deal with this developmental issue non- nepotistic juveniles nepotistic adults right in here is what I was showing you before where there was a clear CIB preference but look what happens later on in the summer it seems to disappear what's going on in the summer really is the name of the game is no longer social the name of the game is fat if you are a ground squirrel you cannot have too much body fat with you when you go into hibernation because you don't cash food yes you turn your physiology almost off but you still need calories to keep you going so out here what's going on is a lot of intense foraging are these preferences retained they're there in juveniles so how do we answer this question well the first thing that we do is send the squirrels back to Michigan where they hibernate individually deep torper for a period of about eight months importantly this is solitary they're removed from all con specifics we are then going to assess their social preferences after this hibernation period we are going to do the same kind of paired encounters that we had done before as soon as we take them out of the cold room and then about a week later we're going to ship them to California put them in the outdoor enclosures and watch them for a period of time both the paired encounter data and the outdoor enclosure data show that the preferences that we saw in juvenal the play partner preferences are social preferences that are still there in adulthood so for the paired encounters if we look at the female female pairs non siblings are significantly more agonistic now remember last year it was a an amicable cooperative play now we're looking at agonism in the case of both females and male pairs it's clear that non siblings are the targets of agonism more often than our siblings when we watch watch them for a period of time in the outdoor enclosure in two replicates again remember we're looking at agonism siblings are significantly less agonistic toward each other than non-ibs in both replicas so it does appear possible that adult preferences develop out of juvenile's preferences sadly let me move away from the ground squirrels at least sad for me U to talk about a couple of more uh examples of kin selection U tiger salamander tadpole have read Hamilton or they appear to these Tad poles will cannibalize nonkin and avoid eating kin unless they're very hungry so when two or three females osit in the same Pond you have from a tadpole's point of view both some relatives and non-relatives the name of the game is to develop as quickly as you can before this Pond dries up you can develop faster if you get more food so what's food if you're a tadpole other tadpoles are but nonkin are eaten rather than kin however if there is very little food available and the pond is getting very very small guess what happens they start eating relatives Direct Fitness Matters more than indirect Fitness picture from the very beginning these are big-headed worker ants who behave very much like a number of other you social insects that is uh the uh ants bees and wasps as a result of an unusual sex determination system in the usocial insect individuals are more closely related to their sisters than their brothers and they're more closely related to their sisters than they are their own offspring males arise from an unfertilized egg females from a fertilized egg as a result of that the coefficient of relationship between sisters is 3 fours not 1/2 but 3/4s the coefficient of relationship between a sister and her brother is only one qu coefficient of relationship between a female and her Offspring is .5 these workers do not produce eggs themselves what they do do is care for eggs produced by the queen and guess how they bias their care they take more care of their future sisters than they do of their future brothers and the ratio is 3:1 if you want to do the math divide 3/4 by one4 finally uh Cooperative uh breeding birds and mammals have been described this is the Florida scrub j a classic helper at the nest um Florida Scrub Jays this is a male helper this is an individual who is an adult and physiologically capable of breeding however rather than breed he stays home and assists his parents rear who their offspring and his siblings rather than breeding on his own so consistent with a hamiltonian explanation now the other thing I should say if this male has a breeding opportunity next door he will take it rather than stay home and help Direct Fitness trumps indirect Fitness but kinship and competition not everything is as straightforward as Hamilton might have led us to believe although I think if you read carefully he still got these right Mir cats and babysitting uh as an excuse to watch TV how many of you watch mircat Manor oh come on raise your hands be it's it's fun most of the dialogue I am comfortable as a naturalist and and a biologist it gets a little cutesy at times um but the point I want to make there are helpers at the nest in Mir cats this right here is an adult who did not sire no did not she a she did not give birth to this baby and yet this babysitter will spend time at the natal burrow when all the other adults are going off feeding her weight will go down over time she is paying a price importantly her helping is not correlated with kinship so a simple hamiltonian argument does not explain this babysitting behavior in beer cats even more dramatic are these male fig wasps their rearing ecology is very interesting an adult female will stick her over repositor through a fig and lay eggs in that and another female can lay eggs in that and another female can lay eggs in that within the Fig the male eggs and the female eggs but the focus here is on males hatch and then the females hatch and what happens mating but before mating what happens what happens is very intense fighting between males and they don't avoid Brothers this fighting is very intense in fact fratricide is common in certain species of fig wasps so clearly these males are not behaving in ways that benefit their non descendant relatives all right we're just about there the impetus behind our meeting tonight was the birth of Charles Darwin and a book that he wrote after thinking about it for 20 years um so what I want to do is uh wrap up by following Darwin's lead in his second uh great book sexual selection and The Descent of Man in which he offered some explicit thoughts about human behavior um in doing so I must confess that I feel like I'm skating on thin ice for uh a couple of reasons actually now third reason I'm looking around I realize there are some of my psychology colleagues uh in the office or in the in the audience that's one of the reasons okay so first um why am I anxious well I have relied extensively on darwinian Theory and its extensions uh to explain my work in non-human animal behavior um my own work has given me very little contact with people although some of my best friends are yeah um second there are a number of evolutionary social scientists who have been studying Behavior human behavior through a darwinian lens um however this approach is relatively new and I think a lot of empirical work uh needs to be done before we will fully appreciate the real value of a darwinian framework work I'm convinced it's going to be there but as an empiricist I have to wait and see so having said that let me move cautiously out onto the thin ice do the words human cooperation or human altruism represent a Darwin darwinian contradiction uh given everything that I've said about selfish individuals and their genes well my answer is a clear no uh Richard Dawkins wrote The Selfish Gene in 1976 uh Second Edition in 1989 the single most readable explanation of genes of the gene eye view of evolution the quintessential Gene centered book in The Selfish Gene Dawkins gives us a useful distinction uh between genes the selfish units that pass from one generation to the next and vehicles the bodies that live the day-to-day lives in the service of those selfish genes so when Vehicles share interest in common so Dawkins argues cooperation can be beneficial in a darwinian sense shared interests can enhance cooperation this is one of those pictures that you just couldn't believe it when you found it to me this picture represents a TR striking example of just how dramatically competition can turn into cooperation when shared interests align suddenly notice this is not a picture of the Republican Senate who don't seem to anyway Dawkins made an even Bolder statement than this claim about vehicles uh and genes can we act against our own genetic interest yes given according to Dawkins given the brain that selection has fashioned in us he argues that we can choose to act against our own genetic interests we can rebel against these tyrants so thinking about selfish genes and Cooperative ve Vehicles may not fit with how you think about human cooperation but let's remember the ways in which cooperation is at the very core of so much of what we do as a result of kinship and reciprocity no surprise so Andrew Carnegie knew that nepotism was its own reward and didn't require uh a financial boost cooperation through reciprocity is such a part of our nature that if you say to anyone I'll scratch your back if you scratch mine they get it there are at least a couple of routes that evolutionary social scientists have been thinking about with respect to cooperation and altruism reputation management reputations manner enormously to social group living creatures like us to primates in general in fact and we view people who have a reputation for cooperation as ideal social partners and we would like to be viewed similarly I think a link between cooperation and building a good reputation can start a positive feedback loop that leads to more and more cooperation altruistic punishment what's that altruistic punishment involves three individuals a is the cheater who treats B unfairly the victim individual c is the altruist who will incur a cost to punish the cheater despite getting no benefit so when economists play these kinds of games where a is giving money to B if C is not happy with the amount of money a gives to b c can punish a by taking money away from a it goes out of the game and C has to pay to do it gets nothing from it altruistic punishment we seem to Value fairness in Social exchanges or at least that's one interpretation of this and altruistic punishment may result when our sense of fairness is violated you might be interested to know that this altruistic punishment has also been described in non-human primates which suggests that social policing has long long been a part of our primate ancestry and I would like to leave you with one final thought about cooperation and the role it played in the evolution of our ancestors and still plays today the many faces of cooperation the title of a book by Bigalow as I said cooperation based on shared interest is common in humans and cooperation may help us solve lots of problems that said let's remember that cooperation can be a means to serve many ends utterly true profoundly wor worrisome cooperation did it hopefully cooperation can control it and in order to answer some questions I'll leave you with something a little bit more uh enjoyable to read the last I believe it's the last literally the last sentence of Darwin's Origin so thank you very much for your attention I'll be glad to try and answer questions as you read along y so uh there are a group of people upstairs and um I won't be uh hurt at all especially my students who should be studying for their exam anyone that wants to leave please do so anyone that wants to stay for questions including those people upstairs I'm going to wait until they come down and you know a minute or so and then I'm happy to answer questions for um a few minutes so if you want to leave do so stick around if you have questions all right I'm uh willing to talk loudly here and uh people want to continue to leave that's fine anyone that's coming in that's fine too questions that I can try and answer you're putting your code on or a question I'm um if kin selection doesn't explain those intriguing Mir cats that incur this cost for babysitting they're not taking care of their relatives what does um Mir cats are a very interesting example of a species um that displays High reproductive skew the dominant adult male and female in the group are the Breeders everybody else is a Helper and that's one of the reasons that mircat Manor is so interesting because there's all kinds of intrigue going on among the non- Breeders how is a mircat successful in a darwinian framework by becoming a breeder groups of Mir cats are better able to defend territories large groups are better able to defend territories and breeding resources than small groups so taking care of this non-relative may give you a small Advantage toward a larger territory and maybe becoming a breeder that's the Tim clutton Brock explanation to date um no evidence for group selection one of the requirements for group selection is independent groups in which individuals aren't moving back and forth because if you have individuals moving back and forth you don't have groups who are behaving for the group and in mircat you don't have this degree of isolation in fact that's one of the general problems with group selection at least the early models required groups to be so closed that it it's just not the way it is in the real world yes John hogland would say no belding's ground squirrels aren't the Cadillac of mammals prairie dogs are this is somebody who is he's probably watched them for 20,000 hours um so the question thank you uh the question was what about prairie dogs um a lot of uh the ground squirrel story is parall with prairie dogs uh the alarm calls in particular um although one interesting thing prairie dog males call guess what prairie dog males do after mating with a female they stay right there so they may be good Dads in that they're warning uh their uh their offspring the females also call in ways that are very similar uh to ground squirrel so a similar kin selected argument yes how um so this is my opportunity uh to to uh tell you about these females in the three hours the the qu I'm going to uh rephrase the question so if she mates with these two males during the same period what happens Sherman's DNA analysis shows us that of these four kids these two were sired by one male and these two were sired by the other male and females typically mate with 2.4 as I recall males so multiple mating is the rule not the exception so when I was talking about siblings I'm lying I really should talk about litter mates because some of them are full sibs and some are halfs what is remarkable is that when Sherman watch watches these females as adults in the field the littermate full sisters cooperate more and fight less than do the littermate half sisters these are individuals that gestated in the same uterus suckled from the same mom live together for the same 25-day period and they still Hamilton would be proud can distinguish a full SI Litter Mate from a half siib Litter Mate does that answer it so what is the recog me so what is the recognition mechanism it's Alla factly mediated and the answer um is something that uh when we proposed it I thought well we were just trying to be thorough I didn't know that uh eventually we would be able to demonstrate this self-referent phenotype matching the argument here is that a ground squirrel she because it's a female story a ground squirrel knows very well what she smells like when she encounters another individual to be very anthropomorphic she says how similar is your smell to me if you smell a whole lot like me and if you're familiar because we grew up together I'll put you in the full SI category on the other hand if we grew up together and you smell only a little bit like me I'll put you in the half siib category so it's similarity to self not cognitive awareness or anything like that but they behave as though they understand their own smell and do this compare and contrast so you looked at the biochemical signatures to generate these old factory responses have have we looked at the the biochemical basis of these old factory signatures um that's a tough one to do in mammals in general the people that have made a lot of progress have been looking at hydrocarbons in uh usocial insects and they have a pretty good handle on it what um has been done Jill Mato a um psychologist a former student of mine at the University of Chicago asks the ground squirrels to do an old factory assay so she will present to a subject an odor from and by doing controlled breeding she can create these odors an odor from a full sib or a half sib or a cousin and by breeding she can also create I'm not going to get it right a sib that is more than a sib if if a brother and sister inbreed the offer spring are full sibs they share more than half of their genes in common Jill has played around with this and what she discovers is the ground squirrels identify identify identify identify and when it gets Beyond cousin it stops so it looks like that's when uh less than 12 and a half% of genes shared in common that's when they start having problems so pretty fine uh discriminations based on the nose what the um actual basis of these signals is it may have something to do with the MHC system the major hist compatibility complex there's a lot of theorizing along that yes I'm not I'm I'm sorry I still can't hear ah in very intriguing question if you're interested you should volunteer to be a field assistant with Jill Mato because she's the question um is about mate Choice which is the other functional explanation for kin recognition mechanism is nepotism is one explanation the other is mate Choice um everyone knows that avoiding inbreeding is a good thing do and ground squirrels avoid inbreeding um there are other reasons why selecting certain mates would be beneficial like choosing a mate whose immune system will complement yours rather than be just like yours so old factory cues are important in mate Choice ground squirrels do uh avoid inbreeding and in some of the studies that Jill has done because she needs to create varying degrees of relatedness she does breedings where she will put males and females together who are relatives and they and they didn't grow up together and they won't mate with one another so they're using their recognition here to avoid inbreeding rather than to be nepotist yes I observed a colony of ants uh that's one that I don't have a good answer for it's certainly the case U that ants in colonies will remove debris including other dead ants and that's probably just about uh Colony hygiene um I don't know of any evidence that this is uh for food for cannibalism case of ground squirrels one of the functional explanations for cannibalism or approximate explanations is food um in ants I I don't think that it's that so this is theiry my yeah so this these ants were in her kitchen they weren't in their colony um your kitchen is a novel environment for an ant and it's perhaps not surprising that the behavior that has been part of their evolutionary past is manifested even in this environment that somehow isn't quite right that's the best I can do so you don't think this some honorable no I don't think it's some sort of honorable act and I'm very glad you didn't ask that about a primate because I don't know in ants I'm not worried about it um it gets more complicated yes medially orally how doav model do we assume that all behaviors are mediated through our gen or through the expression of our gen or or can they they OCC outside that realm and if so then behavior um there's no question but what studying Behavior if you want to link link it to genes uh is a real challenge um much more so than linking genes to Anatomy or physiology but one of the things that Darwin was very very clear about is he was Pres presenting a mechanism that could account for the evolution of anatomy physiology behavior and even psychology so while the link between genes and the phenotype in anatomy and physiology maybe we're starting to get a handle on it the connection to behavior is much more challenging although there are some dramatic uh examples especially of single Gene differences that cause real differences in Behavior um I would think that to me the answer to your question is yes Behavior evolves and is subject to the same laws of selection is anatomy and physiology and if you really want proof come back in 50 years lots of questions which I believe me I I'm happy to talk but well let me let me say this if anyone wants to leave do so at any time you can't because you're writing with me I'll two or three questions so in the back oh oh yeah um is evolution uh still going on today in humans and if so what what signs um my answer was going to be oh I talk about the sticklebacks and the HIV resistance and mosquitoes but you asked about humans the problem and this was a problem that Darwin confronted Evolution takes place across many generations so it's simply the case that we cannot see change over many generations given our lifespans I do think there is a lot of indirect evidence um one very clear example uh is the changes that have occurred in other organisms as a result of our choice to use antibiotics we are changing ourselves not not genetically but as a result of antibiotics that we use or don't use they're are different genes that are being transmitted than if we had not used them so I think that evolution by natural selection is still going on but I can't point to uh empirical evidence in the sense that were taller or smarter or behaving differently it it's more an argument based on the whole logic of Darwinism and part of what Darwin argued is we are subject to the same forces and laws of nature as our other uh organisms uh yes so the way I hear the question it's about competition uh between relatives I don't know that I heard you say competition but that's because they are Sim if individuals share genes in common and as a result share behavior in common could it be that two brothers are interested in the same woman because their genetics indicate interest they are competitors with one another and Hamilton was very aware of that in making his arguments about Inclusive fitness um in the case of fig wasps for example he knew that part of the problem was brother others were competing with one another and they were fighting to the death did that make sense he said it made sense because Direct Fitness is not devalued like indirect Fitness is by this coefficient of relationship so competition between relatives is is part of the story it's part of the model it hasn't been studied to the degree that the cooperation nepotism stuff has one more question Rel soal chimpanzees real straightforward that's yeah chimps so um the question had to do with larger uh groups societies communities uh Nations and how might selection work uh under those circumstances this is where it's very easy to start thinking in group selection terms and a lot of the times that'll take you in the wrong direction um when asking about large group group cooperation it isn't a bad idea to ask what do the individuals who make up that group get from large group cooperation um and there certainly are uh primate examples and I think chimps are a good one some of the citations uh whales and uh Dolphins as well where you have small groups that come together uh fuse and then fision and sometimes there are larger groups uh that are together so that kind of of stratification group size is part of species other than than humans uh trying to make sense out of their behavior in a functional framework is a real challenge that's why I like watching pairs of ground squirrels uh interact or why I like to watch them play that's just a lot of fun so thank you very much for your attention

Channel: University of Oregon

Views: 8,963

Keywords: the, evolution, of, cooperation, hi

Id: CYH0k7Nkons

Length: 91min 48sec (5508 seconds)

Published: Wed Jul 14 2010