December 14, 2009

Joan Roughgarden on social evolution

Second part in a series about sex, gender and nature. In this post I look at the social selection theory of Joan Roughgarden.

Joan Roughgarden is a professor in evolutionary biology over at Stanford. I found her via a review of her new book The Genial Gene in the New Scientist.

The Genial Gene is one of the most radical attacks on Darwin I have seen in a long time. Not that she is a creationist arguing against natural selection, mind you. She does not, but she finds that the biologist's obsession with sexual selection to be questionable, and she and her research team puts up a fascinating alternative, called social selection.

Sexual selection

Sexual selection is based on the idea that individuals battle for their gene's survival in a fierce completion to get laid and get as many descendants as possible.

If you watch nature programs on Discovery or National Geographic you hear the same story over and over again: The tail of the peacock is large and colorful so that the male can attract females and have sex with them.

This narrative also confirms the stereotypes of human gender roles. According to Darwin males are passionate and females are coy. Still, the females have one important sphere of power: They select which male to have sex with, which is why males compete so hard between them. The fast and furious gets the girl.

This is relevant for transpeople, because these theories strengthen the social stereotypes of what it is to male or female. Any deviation from these stereotypes are therefore easily defined as something unnatural (in the true meaning of the word) and therefore something negative.

Sex and roles

Roughgarden does not deny that there males and females have different roles in the animal kingdom. But she does two things that are important for our understanding of the natural basis for sex differences:
  1. She reinterprets the behavior of males and females according to a new overarching understanding of evolution. By doing that she kills some of the stereotypes.

  2. She adds variety to the behavior of both males and females. There is no ideal macho male or sexy chick out there. In some species there are even different types of males and females, types that look and behave differently from others of the same sex.
Choosing a mate

The social selection theory of Roughgarden and her friends downplay the role of aggression and completion and focus instead on collaboration. She argues convincingly that there is no way the peacock hen can determine which male has the best genes based on the look of his tail. Indeed, research shows that the female disregard male plumage (Roughgarden 2009, p. 37).

Instead Roughgarden believes the female chooses to mate with the one she reckons will be the best to help her raise her offspring. Actually how the hen determines the parental capabilities of the male is a bit unclear to me, but in this respect her theory is at least as plausible as the old one.

Moreover, her theory (as opposed to the sexual selection theory) does not rest on the female's capability of finding the best man. You see, there is no hierarchy of genetic quality:

"All males are equivalent in genetic quality, except a rare fraction that obviously contain deleterious mutations and are present in a mutation-selection balance" (2009, p. 240).

I can remember how I as a young man reading about evolution, found it so hard to make sexual selection fit with what I saw around me. Clearly, it was not just the Queen of the Prom or the sexy soccer player that got kids? Most of my class mates got offspring, regardless of their looks or the brand of their car.

And if only the "fittest" of animals get offspring, why don't they all look the same? Why is there so much variation between individuals?

Reading Roughgarden makes it all make more sense, even if I think she downplays the role of aggression and violence a bit too much.

Compassionate Darwinism

Roughgarden says:

"According to social selection, what each sex does is subject to negotiation in local circumstances and statistical regularities in sex roles reflect commonness of circumstance.... Natural selection arises from differences in the number of offspring successfully reared, and particular behaviors are viewed as contributing to producing offspring and to building and maintaining a social infrastructure within which offspring are reared (Roughgarden 2009, p. 239)."

It is not the one who gets laid most often that win the race, but the one that manages to help his or her offspring survive through childhood. The best way of ensuring that is through collaboration and the division of labor, and that requires other skills than aggression and deceit.


Roughgarden again and again points to the enormous amount of variety found in nature. Collaboration can take many forms, and the behavior also changes over time. This is why closely related species like the chimpanzee, the bonobo and homo sapiens behave so differently.

There are, however, logical -- yes, even mathematical -- models that explain why such models of collaboration helps the survival of the species. I am not going into the details here, but if you have a mathematically inclined mind, take a look at The Genial Gene. In that book she demonstrates through game theory that collaboration is more effective than cheating for the survival of your own genetic lineage.

Sex and collaboration

According to the sexual selection narrative, male and females are in conflict and cooperation is at best a secondary development.

In Roughgarden's world things are different:

"According to social selection, male and female mates begin with a cooperative relationship because they have committed themselves to a common 'bank account' of evolutionary success. Their offspring represent indivisible earnings from a common investment. As such, conflict develops only secondarily if a division of labor cannot be successfully negotiated."

Roughgarden takes this propensity towards collaboration so far that she argues that males are not promiscuous by default. Male promiscuity is a strategy of last resort that occurs when males are excluded from control of offspring rearing. (I am not so sure about this one, especially when it comes to the males of homo sapiens, but I am willing to go give her -- and men -- the benefit of doubt.)

Sexual selection theory on the other hand describes monogamy as an entrapment of males by females. Males do not want all the hassle of rearing kids, but they accept it anyway in order to get laid.

Roughgarden takes the logic of collaboration down to the level of sperm and eggs.

In biology the difference between male and female is determined on the basis of the size of the gametes (sex cells). Following the logic of sexual selection the sperm seem to be cheating on the egg by forcing "her" to do all the hard work. In social selection the difference in sizes is a practical way of ensuring a successful conception. The big egg is easier to find for the sperm. Moreover, it contains the provisions needed for the first period of growth.

Power cliques

So what about the peacock's tail?

Well, Roughgarden does not think male ornaments (feathers, antlers etc.) are there for the female to judge the genetic quality of the male. She believes male and female ornaments serve as "admission tickets" to "power-holding cliques" that control the opportunity for successful rearing of offspring.

Again, this makes sense to me. A man doesn't buy an expensive car just to impress the girls. He buys it to impress his mates. He signals that he is successful and that he is one to be invited to the parties of the in-crowd.

Again and again I have been told that women dress up etc. to attract males, but the fact is that most men (apart from cross-dressers, that is :-) are unable to distinguish one brand of make-up, clothing or perfume from another. They will find a decently dressed woman attractive without knowing the secret language of women. The reason women put so much effort into shopping and brands, is first of all that they want to fit in with their fellow sisters, i.e. "the power cliques" of Roughgarden.

All right, but if this is the case, why doesn't the peacock hen have colorful plumage? The hens should, like human women, also strive to join cliques, right?

This is where Roughgarden gets a little vague. She has no general explanation of why male animals, as Darwin argued, seems to have more ornaments in general. In the case of the peacock, however, the explanation is simple: The female protects the eggs, so she has developed camouflage colors. I guess all the blue hens were killed off before their eggs hatched.

Another obvious argument would be that our tendency of interpreting blue feathers as more sexy than brown feathers, or big antlers as more impressive than no antlers, is biased. The male peacock clearly find the brown hen amazingly attractive.

Why is woman more ornamental?

As you probably have understood by now, I find this immensely fascinating, and again I am reminded of discussions I had when I was younger.

I guess it was the crossdreamer in me that had to ask the obvious question: If the male is the one with the colorful feathers, why is it that it is the human males who are grey and bland and the human females who are beautiful, colorful and have the more prominent curvy "ornaments"?

I admit I am a bit gynephiliacly biased here, but my impression is strengthened by the fact that in most cultures women also wear more ornamental and colorful clothes.

Believe it or not, but evolutionary biologists have taken the lack of male plumage seriously. Some of them argue that the human male ornament (the one used to impress the girls) is not their body but their brain. Men have developed huge brains to outsmart other men and thereby win their way into a girls heart. (No, I am not making this up!)

This immediately leads to the question: Why have females developed equally smart brains? Well, to appreciate the genetic quality of the male brain, of course!

Evolutionary psychologist Geoffrey Miller puts it this way:

"If hominid females happened to develop a sexual preference for creative intelligence, then males with more creative intelligence would attract more sexual partners and would produce more offspring. Those offspring would inherit both the taste for clever courtship and the capacity for producing it. Over many generations, average creative intelligence in the lineage would increase rapidly, perhaps explaining why brain size tripled in just two million years."

Note that Miller doesn't make the obvious conclusion: that the females' have gotten bigger brains in order to attract males. Males are clearly not able to appreciate female intelligence! We go for tits and asses, and not for the woman's ability to help us raise our kids. So much for the big brain!

Seriously, I don't know where to begin...

Why am I telling you all this? Because we have to read all of this "authoritative" science for what it is: stories told by men and women like you an me: people who have their own hang-ups and prejudices.

Sexual differences

Let's get back on track:

Sexual selection theory find it hard to explain why some species have no or only small visible differences between the sexes (cp. penguins, sparrows or wolves). They normally explain this by saying that this happens when females lack a sense of aesthetics (!). This very argument does, of course, weaken the whole sexual selection theory.

For Roughgarden "sexual monomorphism" signals the absence of same-sex power cliques: "This should occur in ecological situations where the economically efficient coalition is the coalition of the whole," she says (p. 243).

Sex-role reversal

In some species we see sex-role reversal: The male provide more parental investment than the female.

This should not happen according to the sexual selection narrative. This narrative says that males should do less parenting, because the sperm is smaller than the egg (long story!). According to Roughgarden, this kind of natural feminism makes perfect sense. It is just another type of useful contract based on negotiations in that particular ecological niche.

Transgender animals

It is when Joan Roughgarden goes on to describe "gender multiplicity" it gets really interesting for a transgendered person. That's the topic of my next post.

Postscript on Joan Roughgarden

As I noted earlier, most scientist do not rock the boat. They do not challenge the ruling paradigm for a lot of reasons, the main one being probably that it was the dominant mentality or belief system of a discipline that attracted them to it in the first place.

That leads to the question of why Roughgarden has made such a radical stance.

I didn't read her own history until after having read The Genial Gene. Then it all became clear. Roughgarden is an M2F transsexual.

So far I haven't seen any serious attempts at debunking her theory on the basis of her personal history. It seems her position in the academic world is too strong for that to happen.

[Photo of Roughgarden: Nature]

She did not have to leave Stanford after her transition, partly because of strong support from Condoleezza Rice, the university provost. Yes, we are talking about the Condy Rice! Some times real life is much stranger than fiction.

Anyway, we must be as critical towards her science as we are towards the traditionalists. She openly admit that she has an agenda: to develop a theory with room for outsiders like gays and transsexuals. That might lead her to ignore findings that go against her theory of collaboration.

See also:
Roughgarden on transgender animals


Roughgarden, Joan: The Genial Gene, Berkely 2009. Click here for Google Books excerpt.
Nudging Darwin over the rainbow SFGate on Roughgarden


  1. I've spent a good deal of time reading about biology purely for my own enjoyment, particularly birds, although my interest is in raptors and not game birds. Raptors, by the way, have subtler, but really fascinating sexual dimorphism. But that's beside the point I'm posting here to make. My main point is that if you spend time getting seriously into the subject, you will find that sexual dimorphism is really, really complicated. The number of obscure factors that can affect it, and affect it in ways you'd never assume, is amazing.

    That is why most of that stuff you relayed in your post above comes across as grossly oversimplified or incoherent to me. Either you are leaving a lot out, or the theories in that book leave a lot out. What surprised me most was that you make no mention of The Handicap Principle, which would need to be at the forefront of the discourse in "The Genial Gene" in order for it to be relevant. The picture of the book you are presenting is that it was written by a person not even aware of those more straightforward aspects of sexual dimorphism that can be read about on Wikipedia.

    I find the suggestion that there are "power-holding cliques" among animals like bullfrogs and stag beetles absurd.

  2. Needless to say, any attempt to present two complex books on evolution (and then some) in a blog posts means that I have left a lot out. Roughgarden has also written several peer reviewed papers on these ubjects. I'll take the blame for any misunderstandings or misrepresentation.

    As for the handicap principle, I will just have to conclude that Roughgarden seems to buy the argument "that animals of greater biological fitness signal this status through handicapping behaviour or morphology that effectively lowers this quality", but they do so not to attract the opposite sex, but to gain status in a complex social structure.

    If they were to do so for sexual selection, the hens would have to be able to distinguish between small variants in the "quality" of plumage, which they don't. For acceptance into cliques, such a refined perception is not necessary.

    It can also be that Roughgarden finds the handicap principle besides the point as she argues that there is no "optimal set of traits". You will have to read the Genial Gene to find out more. There are a large number of hypothetical payoff metrices for various social organisations there.

    I am not sure whether Roughgarden is right or not. As I said, she has a tendency of oversimplifying in the same way as her opponent. (But then again, you have to do that in science).

    My point is that her narrative is as coherent and rational as the other, which means that we have to seriously question whether sexual selection theory is born out of cultural prejudices as not based on "objective" scientific observation.

    As you probably will have guessed by now, I do not believe in objective science, only in the benefit of a rational open discourse based on a willingness to listen to the arguments of others and consider observations in a new light. It seems to me that evolutionary biology seems locked into a paradigm that hinders, rather than encourage new discoveries.

  3. Given that there is a chance I have presented Roughgarden in such a way that she will be mistaken for a charlatan, I will add a few quotes regarding her dismissal of sexual selection (2009, pp. 48)

    One of her main arguments is the paradox of the lek.

    She refers to Miller and Moore 2007: "Over time directional selection should erode the genetic variation for secondary-sexual traits [like the peacock's tail], so that females will no longer profit from discriminating among males based on these traits and such preferences should eventually disappear. Yet, females continually display strong preferences for males with relatively elaborate traits."

    Roughgarden points to several attempts at solving this paradox, including a 2007 study where the authors hypothesize that beautiful ornaments in a male do not indicate anything about the male himself, but indicate instead that the male has a good mother; therefore, a female should choose a beautiful male as a mate to endow her daughters with good maternal capability.

    But, as Roughgarden points out, "after several generations all the females should be equally good mothers, again erasing any grounds for females choosing their mates on the basis of genes."

    Roughgarden uses the collared flycatcher as an example:

    "...the male badge is meaningless as an indicator of good genes, because all the genes are equally good by now, and so no inherited female preference for the badge is sustained through evolution." (p. 50)

    Roughgarden asks: "No doubt the gene pool does accumulate small-effect deleterious mutations, but can female choice cleanse it? According to her calculations there is a 1 percent difference between a genetically good and a genetically bad male: "There is simply no way a female in the field can perceptually discern a one percent difference in the fitness of two males."

  4. There are many who have criticized Roughgarden. I take the liberty to quote a letter to Science ( ) by Tommaso Pizzari of the University of Oxford:

    "The problems in the Review are numerous and profound. For example, all 17 points in the Supporting Online Material contain major errors of omission and interpretation. Roughgarden et al. fail to provide either a scholarly review of sexual selection research or a genuine alternative to sexual selection theory. In particular, unlike models of sexual selection, those proposed by Roughgarden et al. cannot apply to most sexually reproducing organisms and crucially are not at all novel, being instead entirely consistent with current sexual selection theory."

    He refers to the Roughgarden article "Reproductive Social Behavior: Cooperative Games to Replace Sexual Selection" (Science Feb 2006 subscription required )

    If you are a member of AAAS or subscribe to Science you can read the extensive debate following Roughgarden's paper, and read Roughgarden et al's comments to this criticism.

    There is far too much for me to go through here, but here is a quote from Roughgarden & Co's final comment:

    "Lessels et al. and Pizzari et al. both argue that the theory we proposed does not constitute a novel approach and is instead entirely consistent with existing sexual selection theory. In support of this claim, Lessells et al. make the distinction between sexual selection as a process and as a theory. We think that even if one accepts this seemingly pedantic distinction, one has to require the authors to select different names for the two concepts they are distinguishing. As is, we are left with sophistry such as “Social selection is a theory of the sexual selection process, therefore it is part of the sexual selection theory,” as the last sentence of Lessells et al. asserts. We believe that nothing will be gained from dithering with such semantics.

    "The difference between our theory and sexual selection is that we claim selection in relation to sex operates through direct ecological benefits and exchange of these through social interactions. On the other hand, sexual selection theory stipulates selection occurs for genetic benefits and says almost nothing on sociality, and what purpose it should serve. Instead, animals are assumed to operate alone, as if in a Skinner’s box, observing only some indirect clues about the other animal’s motives and properties. Our framework is motivated by available empirical evidence and generates testable predictions on the evolution and functioning of reproductive social behavior different than sexual selection. Therefore, social selection is a new hypothesis, whose truth is subject to empirical confirmation or negation."

  5. And, in order to make sure Roughgarden's view is properly presented, here are her and her colleagues' conclusions from the Science paper:

    "Cooperative game theory is the mathematical basis for social selection, an alternative to sexual selection theory (1). The key elements to social selection are: (i) Reproductive social behavior and sexual reproduction are cooperative. Sexual conflict derives from negotiation breakdown. In sexual selection, sexual conflict is primitive and cooperation derived, whereas in social selection sexual cooperation is primitive and conflict derived. Hence, sexual selection and social selection are mutually exclusive theories. (ii) Within reproductive social groups, organisms bargain and trade direct ecological benefits to maximize number of young reared. (iii) Reproductive groups are coalitions of one or both sexes that may include prezygotic "helpers," such as the white-collared male ruff and feminine male bluegill sunfish who assist in courtship, together with postzygotic helpers who assist in raising offspring. Families are reproductive groups whose participants share kinship. (iv) Secondary sex characters are social-inclusionary (SI) traits that permit participating in the species' social system, and exclusion is reproductively lethal. Two types of SI traits include (i) cooperation facilitators like mutual grooming and preening, interlocking vocalizations, between-sex and same-sex sexuality, and other intimacies promoting coordinated team play and the perception of team fitness and (ii) expensive, functionally useless badges like the peacock's tail that are admission tickets to monopolistic resource-controlling coalitions. Any imperfection in an admission ticket is the target of prejudice. In social selection theory, cooperation and team play coexist with prejudice and exclusion."

  6. Thanks Jack! I like the fact that you are exploring the science behind this. This is a very interesting post - and while obviously it's a very complicated theory, the bit about the power groups really stood out to me. I think it deserves more thought and indepth exploration.

    William and I had an experience recently that I just blogged about yesterday. I ended the blog with several questions for AGP's and feelings of "power" vs. "inadequacy" are key in my questions. I would appreciate it very much if you have some time and could read my post and let me know what you think.

  7. More fascinating stuff as always. It's a shame you spoiled it by revealing your own prejudices about Condoleezza Rice. A genuine Conservative is the true liberal--one who believes in individual liberty. Her actions are strange only in that they contradict the typical human behavior to control others displayed beautifully by both Bush and Obama. I was all for America having its first black President and first woman too. Condoleeza Rice is a genuine amazing person. She was just too smart to get into the fray and let herself be savaged by the ignorant masses.

  8. You might be right about my prejudices about Condoleezza Rice, although I am not like so many Europeans you meet these days: you know, the ones who hated everything about Bush and now seems to turn Obama into the Messiah.

    I like Colin Powell as well as Obama!

    Anyway: I did tell the story about Rice helping Roughgarden. Maybe it can help others besides me reconsider their attitude towards Rice.


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