Atomic Nerds

As I’ve often gone on about in the past, to a large degree research and science reporting is something like a game of “telephone”, in which the researchers get one result, attach a tentative conclusion after identifying several more questions that beg for answers, and the reporter reads the conclusion and reports it as a newly defined aspect of reality. It also goes to a deeper level in the structure of scientific publishing itself- while the peer review system has been widely and often justly criticized from within, one point that is relatively rarely brought up is that “peer review” is just that; genetics papers are reviewed by other geneticists, developmental papers are reviewed by other developmental biologists, papers done by social psychologists are reviewed by other social psychologists.

The New York Times brings us another classic example of the science-as-Telephone phemonenom, while the paper itself brings us what is perhaps another good example of the peer review system’s limitations.

The paper is about a gene in mice- also found in other mammals, including humans- that is affected by parental imprinting, an epigenetic phenomenon mainly involved in embryonic development in which the expression of alleles is specifically dependent on whether they were inherited from the embryo’s mother or its father. Imprinting is always the extreme minority special case for alleles, but mammals in particular are so dependent on developmental regulation through this process that it’s likely to be the reason why fish and reptiles can naturally evolve parthenogenetic lines, but mammals never do.

One of the major differences between the journal article and the New York Times article is that the journal article’s reason for excitement is that it (so the paper argues) is the first demonstrated example of an imprinted gene that produces a change in social behavior as well as a change in fetal development; possibly this angle is omitted in the NYT article because journalists love to make science articles more “relevant” to readers by concretely connecting genes to behavior even when researchers refuse to. (Or possibly I’m being genuinely unfair, and the NYT article didn’t make the connection because the reporter lacked the background to see that that’s why the article was exciting, rather than simply seeing the behavioral change as exciting.)

I’m going to add a major caveat here in that I have not read the entirety of the Nature article yet (though I intend to when I lay my hands on a full copy), and for that reason I’m going to skip most of the technical explanation of the gene, what it does normally, and what the researchers made it do in the laboratory in order to mimic the condition of the parental imprinting going the opposite of the way it normally does. Suffice to say the gene directly affects fetal development, but also continues expressing through adulthood and produces a notable change in behavior- the mice behave differently both in a group and when meeting a strange mouse under the conditions the researcher created. I’m going pretty much entirely off the direct claims and explanation in the abstract, and the quotes from one of the researchers in the NYT article.

From a purely genetic perspective, this is a very good study and a very good article: the relationship between the gene and both development and later behavior are clearly demonstrated, and this really is a unique example of an imprinted gene, which really does behave in completely different ways in different tissues. What’s there to quibble with is not the genetics, but the behavior.

Specifically, what the researchers are claiming changes when the direction of imprinting changes about the behavior of the affected mice is social dominance. What did they see that told them the affected mice were more socially dominant than other mice? The mice with the altered gene engaged in more allogrooming- taking the initiative to groom mice within their social groups more often- and also more of what those who are conversant with mouse behavior call barbering, which is not just grooming but actually nipping off some of the fur and whiskers of other mice. Also, when placed inside a tube with a strange mouse, the affected mice were less likely to back away or retreat.

The interpretation of barbering as an expression of social dominance seems to be not terribly uncommon- from people who keep caged mice or otherwise study mice in laboratories, not behaviorists or ethologists who have studied mice, because the behavior doesn’t appear in the wild. To those who study such things, the consensus seems to be that barbering is abnormal behavior*, not dominance behavior; it makes absolutely no sense in the context of social grooming behavior across multiple species in the wild. Grooming behavior serves a group-bonding, stress-lowering** function, and to the extent that social dominance plays a role, it’s that dominant animals tend to get groomed more, not groom others more. Like getting smiles and waves more often, the bosses and the beautiful people tend to benefit more from initiation of interaction by others. Holding someone else down and pulling out some of their hair for no particular reason or provocation neither benefits the initiator nor sends any message to the recipient. (In the case of mice and whiskers, this could be interpreted as actively harming them- a lab or captive mouse doesn’t need its whiskers for much, but a wild mouse certainly does.)

The geneticist, to whom mice are mostly a living Lego kit, looks at a behavior and tries to put into a context: it must mean something, so social dominance is as good a theory as any, since going up to someone and chewing off their hair seems like behavior unlikely to be tolerated without a compelling reason. Since parental imprinting has evolutionary implications and is often studied in the case of intersex conflict and mother-fetus conflict, it seems sensible to try and put the interpreted behavior in an evolutionary context, as one of the researchers does in the NYT article:

We’ve shown the extreme,” he said. “But you might have a more subtle variation in how much this behavior is expressed.”

Males may be passing on versions of the gene that vary in strength to different offspring as a means of guaranteeing their legacy.

“It’s a risky strategy to set yourself up as a leader of the pack,” he said. “It’s a good idea to disperse these characteristics through your offspring where some could be regular members and others could be leaders of the group.

A behaviorist familiar with the behavior of the species would look at the same mouse, note the behavior in question doesn’t occur in the wild but does occur in captivity among a population that varies from somewhat to extraordinarily inbred and that has no choices regarding the identity and number of its cagemates, and and come to the conclusion that the behavior is not necessarily a valid case for considering the evolution of wild mice- particularly in the case of testing mice by sticking them in a tube with a strange mouse. Behaviorists know now that captive animals behave very differently than wild animals; one of the more infamous examples involves the social behavior of wolves and the “alpha-beta-omega” rigid pack order David Mech originally helped lay out during the study of captive wolves- which Dr. Mech is now trying hard to undo following extensive research on wild packs, which are mostly family groups with a social order that only barely resembles that of captive wolves.

Wild rodents living in tunnels communicate extensively by urine markers and smell; two strange mice would easily be able to avoid one another, and would prefer to do so. The “two mice in a tube” represents a potential wild encounter about as well as dumping two humans that were strangers to one another into a featureless and inescapable cube*** would represent normal human interaction. Mice aren’t Legos; they’re social, complex animals whose behavior normally has a context that is mating, foraging, and living socially in the wild rather than cages with food pellets and water bottles. Knowing what we do about normal human behavior because we ARE humans, how would you interpret a human in the case of a hypothetical cube experiment that immediately stood in the middle of the cube and refused to give ground rather than retreating to a corner and then potentially making careful approaches after evaluating their cube-mate- a dominant, confident individual… or one that had a screw loose? Confident people used to social dominance will probably be the first to make an approach- but that doesn’t mean they casually stand within the bad-breath zone of total strangers. That’s generally the behavior of weird people, and is often defined as creepy beyond that.

Mice that chew their cagemates’ hair off and don’t have the instinctive response to give space to a completely unknown stranger in a tight space aren’t necessarily socially dominant, they’re socially wrong. And while that is most certainly worth studying, it’s worth studying within the context of mouse behavior AND neurobiology rather than neurobiology and guesswork, let alone guesswork about the evolutionary implications.

*Thanks to Bernard Crespi, whose comment on the article in question led me to that very good source. He seems to have written an interesting post for the Evolution and Medicine Review blog that is no doubt better than mine, but my virus software is warning me the link holds a Trojan, so I’m not going to link it for now- hopefully later it will be cleaned and I can link it then.

**Do you have a cat, dog, or horse? Do you pet them? Do they sometimes lick or rub or nibble you while you pet them? Congratulations on your mutually rewarding allogrooming. It tends to be a little compulsive for social species.

***Insert your own Dilbert- like joke about corporate life here.

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