Science Question from a Toddler: How ants evolve

Consider, if you will, the issue of sex and the single ant. Male ants are born into what is, essentially, a giant sorority house, vastly outnumbered by female workers. But that doesn't mean male ants are living out some Hugh Hefner harem fantasy. Most of those many, many females in the ant colony are completely uninterested in sex.

Only queen ants breed. During the course of their lives, they will produce all the baby ants born in the colony. In fact, in some (but, contrary to popular belief, not all) species, the drones' options are narrowed down to exactly one queen—effectively turning that sorority house into a sausage fest. A virgin queen goes on her mating flight, and the drones will get one shot to pass on their genetic material. Afterwards, the males die, and the queen uses their seed to give birth to daughters upon daughters ... most of which will be sterile workers.

On the surface, that system doesn't make a lot of sense. Evolution works because of natural selection, right? And that's based on sex—who manages to survive to adulthood and who manages to find a mate or mates. It's all about passing on your genes to the next generation.

So why would any species evolve a whole class of individuals who never have sex, and never have offspring?

That was basically the question posed by anonymous reader who asked, "If only the queen ant breeds, how does natural selection work for the other ants?" And it's a damn good question, something that confuses people far older than toddler age. In fact, that very conundrum stumped Charles Darwin himself and, today, it sits at the heart of a knock-down fight within the fields of evolutionary biology and social insect studies.

First, a quick reminder about how evolution works.

It starts with natural selection. Different traits improve an individual's chances of surviving to adulthood, finding a mate (or mates), and producing offspring. Other traits diminish those chances. Selection favors those randomly generated traits that help themselves be passed on to the next generation. Over time, some of those traits might prove beneficial enough that they get incorporated into a species gene pool in a fundamental way.

Environment matters, too, because natural selection is all about what works in your physical and social environment. The traits that help a fish survive and reproduce are different from those that help humans. Those that help humans in a desert are different from those that help humans in the Arctic. Selection happens at the level of individuals, but it can alter populations.

If you keep things this simple, then ants really don't make a lot of sense. How can natural selection happen, if the designated breeder is chosen by birth, and not by fitness? And how does not breeding benefit all the individual female workers enough to make that trait stick, as a fundamental aspect of a species?

The answer, of course, is that evolution is a lot more complicated than the simplified explanation makes it sound.

Kith and Kin

Ever since Darwin's time, scientists have looked for ways to reconcile the theory of natural selection with the weird lifestyles of bees, ants, and other social insects. Today, the generally accepted explanation goes something like this: When your relatives benefit, you benefit, too.

That's because, to some degree, you and your relatives share genes. If you don't have any children, but you help ensure that your sister's children survive to adulthood and have kids of their own, then you've scored a point or two in the game of natural selection. Some of your genes got passed down.

Sure, your score would be higher if you'd had kids of your own who carried more of your genes. But natural selection isn't all-or-nothing. Your nieces, nephews, and cousins are better than no genetic descendants at all.

That's kin selection, and it's the mechanism behind something called inclusive fitness theory. The idea there: Species will evolve traits for cooperation—even traits that force them to sacrifice themselves for others—if the benefit outweighs what they loose. So, you might forgo having kids of your own if, by doing that, you enable enough nieces and nephews to survive and breed. You can see already how this relates to the ant problem.

"Any gene that rendered you sterile but enabled you to make other copies of that gene would survive," says Jerry Coyne, a professor in the department of ecology and evolution at the University of Chicago. "If you become sterile but you help your mother produce more workers and make bigger colonies, that would have an advantage. It seems maladaptive but it would be actually adaptive."

Worker ants, the maiden aunts of the ant kingdom, make sense because they enable their mother, aunts, or sisters (remember, colonies often have more than one queen) to produce hundreds of other workers and drones, and to produce the next generation of queens.

But not everybody buys that explanation. One of the most interesting things about this particular Science Question from a Toddler is the way it ties into current events. The tiny ant turns out to be the perfect tool for reminding us that science doesn't happen by reputation alone. Even the biggest names can, and will, be called out if they publish easily disproven research.

Move That Rubber Tree Plant

Among the minority of researchers who think kin selection and inclusive fitness aren't the right way to explain the existence of worker ants: Edward O. Wilson.

You probably recognize that name, and with good reason. Wilson is one of the most well-known names in science, certainly the most well-known researcher of social insects. The man has two Pulitzers. When science journalists talk about "what E.O. Wilson thinks" we usually assume that he's right.

But I can't do that this time.

In August of 2010, Wilson published a paper with two other colleagues that aggressively dismissed inclusive fitness theory entirely. The paper was, to say the least, not well received. The formal rebuttal, published in March, was co-signed by no fewer than 103 different scientists, including Jerry Coyne. I'm not sure whether that's the most people to ever co-author a rebuttal together in a scientific journal, but it's got to be close to the record. Clearly, E.O. Wilson has hit a nerve.

Why? Thats where things get complicated. Nearly everybody agrees that E.O. Wilson was wrong, but there's some disagreement on why he was wrong and just how wrong he was. Meanwhile, Wilson's co-author, Martin Nowak, thinks the people critiquing the paper aren't actually understanding his and Wilson's point very well. This is not a particularly easy debate to summarize.

"I think, honestly, no one understands their arguments, including themselves," says Terry McGlynn, associate professor of biology at California State University Dominguez Hills, and the current president of the North American section of the International Union for the Study of Social Insects. He didn't co-sign the rebuttal, but agrees that Wilson's paper was worth rebutting.

As McGlynn sees it, there are two key problems with the Wilson paper: First, it makes claims about the scientific research surrounding kin selection and inclusive fitness that are demonstrably false.

One of the key mistakes is that the paper claims there's no empirical evidence to support inclusive fitness theory at all. That's blatantly wrong, say McGlynn, Jerry Coyne, and all those co-authors on the rebuttal paper. The truth is that inclusive fitness has been an important part of understanding a range of real-world behaviors, from cooperation to cannibalism.

However, that doesn't mean it's perfect. The Wilson paper stresses that predictions made about ant societies based on inclusive fitness—i.e., how related a group of ants ought to be in order to make the workers' sacrifices make sense—aren't usually correct.

That's true, say McGlynn and Coyne, but it's a matter of degrees, not a matter of the ants turning out to be completely unrelated.

"Inclusive fitness works. Relatedness matters. What you see is that we theoretically expect the ants to be 66% related, but they're only something like 14% related," McGlynn says. "There are clearly benefits to relatedness or these colonies wouldn't be even that related.

This is what brings us to the second problem. The Wilson paper sets up inclusive fitness as a stone fortress to be assailed. It assumes that most other researchers think inclusive fitness is the only explanation you could possibly need for how social systems like those of ants evolved. Then, the paper says that because inclusive fitness doesn't explain everything about ant society, it must be fatally flawed.

And that's just a straw man argument, McGlynn says. Because nobody denies that there's more going on than just relatedness.

For instance, he says, the ants that share a colony have more in common than genetics. "They're living in defensible, constructed nests. The fact that they all live together and have shared defense and shared the benefits of foraging matter," McGlynn says.

Without those things, eusociality—the scientific term for cooperative social systems where labor is divided into strict castes and some of those castes don't breed—doesn't evolve. Kin selection is important, McGlynn says. But it's likely that these shared risks and benefits mattered a lot, too.

Of course, not everybody would agree with McGlynn, either. The last thing you really have to to understand about this debate is that it's really rooted in another—between researchers like McGlynn, who think that the evolution of eusociality has a lot to do with both kin selection and the shared risk/benefit scenarios of what's called "group selection," and researchers like Jerry Coyne, who think that group selection doesn't explain anything that isn't already explained by kin selection. Coyne, and a lot of other evolutionary biologists, pretty much wrote off group selection a long time ago. In fact, that position is well-established enough to often be the default in college classes. But, in recent years, there have been plenty of other researchers—particularly social insect researchers—who've challenged that status quo.

And, while it's very clear that E.O Wilson's paper is wrong—kin selection is important and has not been disproven—it doesn't look like we can say, with as much certainty, that the idea of group selection is wrong.

This should give you the basic overview of the debate. In future stories, I hope to delve more deeply into why group selection is a controversial idea, and why it refuses to die. For now, tell your toddler about kin selection. There's plenty of time to add complexity to the explanation when they're older.

Special thanks to the awesome Zach Shaffer at Arizona State University for turning me on to this debate.

Image: Adrian A. Smith, used with permission and deep gratitude.


  1. I love these science posts! Thank you Maggie! My uncle bought me Anthill by EO Wilson, maybe if I read it now I will find some evidence of his disdain for inclusive fitness.. I have always had a soft spot for ants since my childhood when i used to follow the diplomatic relations of the different colonies in my yard & their skirmishes. As well as SimAnt. Lots of SimAnt.

    1. I always liked SimAnt better than SimCity – it always seemed easier to meet the needs of the ants than those fickle Sims. The Sim games were actually a pretty good balance of fun and education, tho. While I was learning about city planning or basic ant science, I made sure to take a break and occasionally sic a monster on the city or become a spider and chase down unsuspecting ants. Ah, memories.

  2. Maggie, this is wonderful! I’m writing a lecture right now for my freshmen undergrads and I learn so much from your writing about how to explain complex issues simply and effectively. You’re one of the reasons I keep coming back to Boing Boing.

  3. You’d think Wilson would know better than to try a !A = B argument.  Then again, I’ve never heard of the guy so I don’t know what he knows.

  4. For anyone interested in more, a few months back I created an Xtranormal video dramatizing the criticism of the Wilson & Nowak paper. It can be found here: 

    I also followed up with an explanation of what I perceive to be the context in which a paper by Wilson and Nowak generated so much drama (in contrast to the many equally wrong papers published in all sorts of fields every week. That one is here:

    NB: I’m a theoretical evolutionary biologist, and part of my work uses the kin-selection framework, so I’m not an entirely unbiased commenter.

  5. In fact, in some (but, contrary to popular belief, not all) species, the drones’ options are narrowed down to exactly one queen..

    Is this the popular belief? Every book I have seen on ants only mentions colonies releasing many new drones and queens. It would be interesting to know what the exceptions are; they can’t be too common.

  6. This scientific disagreement is also a political one.  E.O. Wilson, eminent as he is, has been known for decades to allow his right-wing politics to drive his scientific conclusions.  He’s the foremost contemporary scientist willing to lend his prestige to what amounts to prettified ‘social darwinism’ – the pseudo-science that would have us believe that everything from rape and racism to war and capitalism is biologically ‘hardwired’ into humans by a version of natural selection that excludes cooperation and mutual aid in any form.  This “selfish gamete” version of evolutionary theory is not only demonstrably false – as the rebuttal to Wilson’s recent paper illustrates – it’s a betrayal of scientific principles in the service of folks in power.  Despite the solid work he’s done in the past, Wilson is now the evolutionary biology equivalent of the climate-change denialists, and should be listened to about as much as they are.

    On the other hand, the broad repudiation of Wilson’s falsifications may help make more visible another strain of evolutionary thinking that’s been around for as long as ‘social darwinism': the one that investigates the myriad ways that cooperation and mutual aid within species and between species are a factor in evolution even as it acts on the basis of individual organisms.  Stephen Jay Gould’s classic essay on the subject – available online here: – was written partly in response to an earlier round of crap from E.O. Wilson. It’s aged better than Wilson’s writing will.

    1. While you are absolutely correct that a scientist should not be influenced by their biases and Wilson clearly would, you can’t really fault him for his beliefs in social Darwinism.  On the low end it’s just a biological justification for a meritocracy and I agree that if you take it to its outermost limits it becomes very dark and unpleasant… but that alone does not make it untrue.  I happen to think there are other reasons it’s untrue and other reasons that maybe we shouldn’t rape smaller people than ourselves, but we cannot reject a theory merely out of fear of its implications. 

      Otherwise we’d all agree climate change isn’t real.  It’s scary.

      1. Using Social Darwinism as a justification for one’s actions is the equivalent of throwing things at the ground because you believe in gravity.

    2. “E.O. Wilson, eminent as he is, has been known for decades to allow his right-wing politics to drive his scientific conclusions.”

      It’s strange, then, that this is the first time I’ve ever heard this accusation.  Especially since I used to work at the Academy of Natural Sciences in Philly!   I worked daily with people who knew Wilson personally and who were definitely not “right wing”… it’s odd that they never mentioned any such thing.

      Can you support this statement with a links to Wilson’s works that you find offensive?

  7. Alright Maggie, another awesome post that enlightens my dearth of science knowledge.  Where can I find more about ant evolution that a nonacademic can understand.

  8. If we’re talking ants and evolution, it seems important to note that ant relatedness is a bit more complicated than human relatedness, since they’re haplodiploid:
    A female ant is actually more closely related to her sisters than to her children, so from a raw self-interest point of view it makes more sense for a female ant to help her mother produce children than to produce children herself.

    I don’t know exactly how this relates to the debate (though they mention that a bit in the Wikipedia article) but it seems like an important bit of context.

  9. As I was reading this, it seemed to make sense to me. Fitness for species is based on the ability to adapt and survive in the environment. Once they have evolved the methods to achieve this in the genetic pattern, combined with the social skills of the colony, the breeder would be as equal as the workers. Though we view the ants as a caste system, the ants may not have the same point of view. It’s a genetic group-think based on the sustainability of the species. Which comes down to many random choices occurring in certain ways. Just thinking out loud here. Then again, I could be wrong. :)

  10. The way I’ve reconciled the question is that an entire colony is like a single organism; the emerging queens are merely like a reproductive vector which confers the genetics of the entire organism.

    New generations of queens are created one to several times each year depending on species, so even though colonies are lesser in numbers than other individual organisms, there is still a lot of room for natural selection.

    Btw, the ants in the picture look an awful lot like California Harvester Ants, who are presently as a species, under attack from the invasive Argentine Ant (not to mention the continual predation by Uncle Milton). Argentine Ants in their new foreign homes are thought to have all descended from a very similar genetic stock which allows them to form super-colonies spanning thousands of miles, which poses ever more amazing questions about the nature of natural selection, social insects, and the environment.

  11. I’m probably missing something, but shouldn’t the question be “how do queen ants evolve?” The worker ants are just an adaption on the part of the queen. 
    oops Joseph V. Kelly just beat me to it , Queen , colony , same thing I think.

    Is it chickens laying eggs to reproduce more chickens, or eggs hatching into chickens to reproduce more eggs ?

  12. It seems that the inclusive fitness idea can make a lot of sense, but not 100% in the way that it’s described above.

    If you say “What does a sterile uncle gain from helping raise his nephews and nieces?” then you have to do some math and odd jumps to say that some of his genes get passed down, and so it benefits *him* in some slight way.

    But if you turn the question around and say “What does a grandmother gain by having two offspring, one of which is sterile but greatly helps in the raising of the grandkids to reproductive age?” then the answer is a lot simpler: If the grandmother can have more viable grandchildren, then more of *her* genes get passed down.

    I think it confuses the matter to say that the sterile uncle helps in order to get his genes passed down. Instead the uncle is helping the grandmother’s genes get passed down, and the grandmother’s genes have been selected such that producing the occasional sterile helper gives them a better chance of reproducing down through the generations.

    So the question isn’t “what do the worker ants get out of being sterile, and how could evolution select for them?” it’s “what does the queen get out of producing hundreds of sterile, obedient workers, and how does evolution select for *her*?” That answer seems to be much simpler.

  13. Move over, Darwin. Take a hike, Creationists. We’re going LAMARCKIAN here.

    Animals respond to adult stresses by helping their offspring pick which alleles to express.

    That’s how a queen ant can produce servants fit for a given situation, even if its sperm donor died long before the situation started.

  14. Just wanted to chime in again about the the awesomeness of this post. Science has never been my best subject and it’s not usually the one I’m most interested in, but Maggie’s posts are incredibly attention-holding and intriguing.

  15. how did I miss the hard evidence that EO is a social darwinist right winger? (not sure Gould is best choice for challenge– esp since he’s not here to defend against his own charges of political desires driving data outcomes)
    I thought EO was an environmentalist & social liberal and that his research on hardwired reasons for behavior was about exploring why, not proving that such things should be. re: the actual topic of ants– didn’t he propose a super organism idea (as mentioned above) which jibes with how relatedness is among ants (also mentioned above– sisters v. children)? Doesn’t that rather fit in with the picture of altruism/cooperation acting at individual & group level (ie, Sapolsky, de Waal, etc)– but with an insect twist?

    1. You missed it because it’s not true. Sociobiology was picked up on by social-darwinist right wing types, but Wilson himself never pushed a political agenda. Attacks like the one above are sort of like saying Einstein advocated the use of nuclear weapons because of his work on relativity. A profile in the Guardian might add some clarity for those unfamiliar with the controversy Sociobiology stirred up.

  16. Maggie, I am disappointed that your post does not accurately present any part of Wilson’s view.  You’ve presented some links, but you’ve also trashed the man’s work as “clearly wrong” without establishing any evidence of error.  The thread your post engendered is spotted with unsupported character assassination as well.

    The loudest of Wilson’s critics have been those who insist that there is no source of altruism other than that rooted in kin selection.  Wilson rightly rejects this view as inconsistent with empirical observation.

    In ancient Britain, fostering and adoption were commonplace.  The descendants of those people built a mighty empire, that could absorb vastly different cultures and races within itself.  These facts may be related; Ruth Patrick once said “Diversity, to me, is the hallmark of a healthy ecosystem”.  Group selection theory explains why genetically unrelated individuals can benefit from co-operation and altruism in a way that explains both history and evolution better than kin selection theory does.

    Does it not seem odd that the proponents of “kin selection is everything” are ignoring experimental results that show they are vastly incorrect?  I mean seriously,  14% instead of 66%?  You are OK with that level of inaccuracy?  If somebody said “my theory predicts this object will measure over 300 degrees centigrade” and you measured it and found it was only 72 degrees, wouldn’t you assume that the theory was no good?  I certainly would; in my world, empirical evidence trumps hearsay every time.

    Also, “lose” is spelled with only one “o”, not two.

    1. Altruism, I made a huge mistake making it the center of an argumentative paper. But it lead me to research the word itself. Altruism and Animals aren’t spoken in one sentence by some  scientist/behaviorists. Some of them even still believe that “animals are incapable of suffering” so they don’t have the capacity to be altruistic because that takes “conscious choice”. 

      I agree with you, altruism and self preservation and passing on the best gene’s are not in the spirit of Comte’s beliefs. Therefor, ants are  BORN to perform everything they do, it’s in their DNA code, they can’t help it, there is no decision making, it’s called instinct. 

      I created a lot of enemies in that course. I argued that all doctors, firefighters, priests and so forth were not living altruistic lives because they were receiving paychecks, it was a career choice, not an altruistic one.  

      I finally came to the conclusion that any truly altruistic act becomes bastardized by the media, they remove the altruism aspect of it and call the doer a “hero”. Altruism is a very selfless act, almost always unrecognized and no satisfaction on the doers part. 

      However, I discovered one thing; witnessing an act of altruism is absolutely life changing and amazing. No article, paper, news report or novel could ever replace witnessing such an event. If it’s filmed, it can only be trusted if it was remotely filmed by something like a traffic camera. 


      Keep Commenting. 

    2. I work in the field, and I’d say from speaking with many of the “critics” that they have a tremendous respect for E. O. Wilson, his early work in the field was inspirational and led many, including myself, into the field of social evolution. 

      But the point is that Nowak and Wilson misrepresented the literature by 1) picking a few, non-representative papers rather than address the body of literature as a whole (see the many replies and critiques of the Nowak paper) and also 2) setting up a straw man argument against the haplodiploidy hypothesis, which although initially compelling was discounted decades ago.

      1. Following the links, I do not see this evidence.  Presumably this is because I can’t afford to spend $64 US on articles behind paywalls, but in the portions of the papers I can read for free, I see that Nowak and Wilson do not deny that inclusive fitness theory fits a subset of empirical evidence, they claim that other explanations are also available and that therefore inclusive fitness theory is unnecessary.  That’s a far cry from denying empirical evidence!  If you can supply me with free access to the papers in question I will be happy to read and discuss them in greater depth.

  17. Wonderful article, very clear.

    Also, Ito the article did in no way trash Wilson, if anything it could be criticised as hero worship, who else has their honours mentioned, the fact is most knowledgeable folks in the field rejected Wilson’s paper. You claim she doesn’t provide any evidence of error but disregard the links that lead you to empirical evidence supporting inclusive fitness theory. You can’t really request evidence besides the evidence that is evident, without appearing a little silly.

  18. I find evolutionary theory interesting but I’m not sure if I get what’s going on here. So I’ll dive rght in and see if people can put me right.

    SO in answer to your initial question “If only the queen ant breeds, how does natural selection work for the other ants?”
    My answer would be – It doesn’t – They don’t breed therefore don’t pass on their genetic code. Full stop. The base line is that any mutations they might have (as separate from those conferred to themselves and their siblings) are lost.For exampleIf there was a genetic mutation in the mother that meant that all her (non-breading)  offspring had lasers on their heads and this meant that the colony survived and prospered then future ants would have lasers on their heads. If 1 single (non-breading) ant has a genetic mutation that means it has a laser on its head it may well help the colony survive but it has no means to pass on this mutation and so the next colony will have no laser ants.

    “How can natural selection happen, if the designated breeder is chosen by birth, and not by fitness? “The designated breeder IS chosen by selection – If the colony fails the Queen dies – no more ants from that line.  The workers weren’t up to the job – it’s the breeders genetics that were responsible for their inability. 

    “And how does not breeding benefit all the individual female workers enough to make that trait stick, as a fundamental aspect of a species?”In the case of ants how could it possibly not stick? If you evolve to the point where you create so many eggs that you need an army of workers to keep them alive, if you then have a mutation that confers breeding powers on all those offspring, both the original colony and all of the offspring’s colony’s will fail – they will have no worker’s left- all the workers are now breeders.

    “how does not breeding benefit all the individual female workers” The answer is that it doesn’t, they have no choice in the matter, it benefits the queen – who does the breeding and therefore get’s to breed again –  they whole basis of natural selection.If the individual workers didn’t work for the good of the queen/colony she/it couldn’t survive therefore the queen/colony is naturally de-selected. So only queens with offspring inclined to help her survive.

    Asking – how did it get to the stage that there are all these non breeding female workers is a different question.

    1. “”And how does not breeding benefit all the individual female workers enough to make that trait stick, as a fundamental aspect of a species?”In the case of ants how could it possibly not stick? If you evolve to the point where you create so many eggs that you need an army of workers to keep them alive, if you then have a mutation that confers breeding powers on all those offspring, both the original colony and all of the offspring’s colony’s will fail – they will have no worker’s left- all the workers are now breeders.”

      Yes, but that doesn’t really answer the question of how co-dependency to such an absolute degree evolved in the first place.  Evolution is a gradual process as well, so the more immediate logic of colony survival is less compelling over greater time scales.  Ant evolution could just as well trend towards de-colonization if co-dependency was the only thing in the way of gene propagation.  

      The short answer to the question is that female ants are more related to their sisters than their offspring.  That creates a logic of kinship.  That logic is expressed through a colonial lifestyle that confers greater reproductive success to the queen and by extension to each individual worker.  Even if a mutation gave breeding powers to workers it would represent little individual advantage, not just a collective disadvantage.

  19. This article was interesting and generally clear, but there’s one place where I feel like the phrasing might actually confuse certain people.   Phrasings like ” you might forgo having kids of your own if, by doing that, you enable enough nieces and nephews to survive and breed” suggest an evolution that is driven by conscious thought as opposed to being an outcome of random processes.  It might be better to say things like “a gene that causes some individuals not to breed, and instead help other carriers of the gene to survive and breed, may well survive better than a gene that just helps all its individual carriers to breed.  It’s the genes, not the individuals, that are the focus of the natural selection phenomenon. 

  20. I am certainly a layperson when it comes to arguments such as this. However, my viewpoint is that colonized insects really are more akin to cells within an organism, rather than individual organisms. With that perspective, it is really the same status as a multi cell organism. The neurons in my brain cannot reproduce my genes like my sperm can, yet it is still necessary for the propagation of my genome. This is true of worker ants as well, just at a different level.

  21. The analogy to a multi-cellular organism is almost, but not quite appropriate.  Somatic cells (those of the body) are exact clones.  They share 100% of the genetic information passed on through gametes.  There is no mystery as to why they don’t break from the organism to reproduce on their own.  Ants, and other eu-social insects are only partially related to their colonial counterparts.  As such, the altruistic explanation leaves some room in the genetic deficit for alternative theories.  And that’s what’s so interesting about the question.  What’s the logic here?

    1. “Somatic cells (those of the body) are exact clones.  They share 100% of the genetic information passed on through gametes.”

      Actually, that turns out not to be universally true. People are often chimerae – statistically, far more women than men, though I don’t know if anyone knows why. Other animals absorb eachother (eg anglerfish, spliced trees, etc). There are a number of other interesting cases where an organism can be made of disparate cells.

      1. Actually, that turns out not to be universally true. People are often chimerae – statistically, far more women than men, though I don’t know if anyone knows why.

        Cell transfer back up the umbilical cord from the fetus causes chimerization in adulthood, although usually just of blood cells. Essentially the mother receives the “cord blood” stem cell transplant, which then goes on to colonize her bone marrow and do its usual thing. This may be to the mothers advantage, in that she has a chance to benefit from any genetic imrovements from her mate, while still retaining her own immune system. The two cell lines cover for each others faults, basically.

  22. To put it the Dawkins way, the workers are part of the queen’s extended phenotype.
    Queens who make sub-standard workers suffer just as surely as beavers who make sub-standard dams.

  23. well, if you think organisms “just” as ADN defense and replication systems, nothing says that that system must be only one organism. if you thing about it, multi cellular life forms are exactly that, a lot of cells, some of them in charge of procreation and other in charge of fetching and processing food (ants are know to actually fetch things that they use a “fertilizer” for the fungii they actually eat) and others defending.

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