Green-beard effects are genes that:
- Produce an effect that can be detected
- Produce preference to others with the same effect
Are there any examples of this in humans?
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2$\begingroup$ Could you expand you question to make it more accessible to users, and thus easier to answer? What 'samples' are you interested in? Do you have an example? Thanks. $\endgroup$– LukeCommented Jun 20, 2012 at 11:10
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1$\begingroup$ So... essentially you are looking for examples of dominant alleles with a clear phenotype? I do not understand your examples, though: racism, wars etc. are all but "easy" situations that definitely cannot be explained [just] in terms of genetics. Also, when you write "sample" do you mean "example"? I am asking because sample has a different meaning. $\endgroup$– nicoCommented Jun 20, 2012 at 16:33
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$\begingroup$ Essensially I am still confused. I feel that altruism toward those who are similar are very much a like altruism toward family members. Yes, it may not be pure genetic. Then what? How, mathematically, those traits reproduce? Does every such traits come with a complementary trait to like those with the traits? Still some part is mathematically missing. $\endgroup$– user4951Commented Jun 20, 2012 at 16:37
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1$\begingroup$ You cannot reduce everything to genetics. Ambient plays a role of paramount importance in all those situations. There are certainly a series (definitely not one) of genes that can influence how much altruist or racist or violent you are, but the education you are given and the culture in which you grow in are much more powerful in shaping your behaviour. $\endgroup$– nicoCommented Jun 20, 2012 at 20:46
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2$\begingroup$ I've reverted all the later changes, they confused the matter more than they helped in my opinion. $\endgroup$– Mad ScientistCommented Jun 21, 2012 at 12:48
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1 Answer
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Your examples are way too broad. A green-beard effect only applies to the effects of a single gene or group of linked genes, not to just any trait. Racism and your Mongol war example are too complex to be explained by this effect. In reality examples will mostly be found in single-celled organisms where expression of a single protein can have whole-organism effects such as causing aggregation, or in larger organisms where some highly visible effect is possible such as a colour change.
There are very few real known examples of the green-beard effect, but four are listed on the Wikipedia page:
- The killing of red ant queens carrying a particular allele by workers with a different allele (Keller & Ross, 1998)
- Altruism in social amoeba resulting from homophilic adhesion of a protein (Queller et al., 2003)
- A multi-locus example in which similarly-coloured male lizards protect one another (Sinervo et al., 2006)
- A neat example in yeast whereby individuals sharing an allele for a particular locus selectively aggregate, preventing those without the allele from benefiting by proxy from their trait (Smukalla et al., 2008)
References
- Keller L, Ross KG. 1998. Selfish genes: a green beard in the red fire ant. Nature 394: 573–575.
- Queller DC, Ponte E, Bozzaro S, Strassmann JE. 2003. Single-Gene Greenbeard Effects in the Social Amoeba Dictyostelium Discoideum. Science 299: 105–106.
- Sinervo B, Chaine A, Clobert J, Calsbeek R, Hazard L, Lancaster L, McAdam AG, Alonzo S, Corrigan G, Hochberg ME. 2006. Self-recognition, color signals, and cycles of greenbeard mutualism and altruism. Proc Natl Acad Sci U S A 103: 7372–7377.
- Smukalla S, Caldara M, Pochet N, Beauvais A, Guadagnini S, Yan C, Vinces MD, Jansen A, Prevost MC, Latgé J-P, et al.. 2008. FLO1 Is a Variable Green Beard Gene that Drives Biofilm-like Cooperation in Budding Yeast. Cell 135: 726–737.
answered Jun 20, 2012 at 22:51
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$\begingroup$ Nice answer, just wanted to point out that obviously "altruism" in the amoeba cannot be extrapolated to altruism in men (not that you are saying that, but I can see such a comment coming) $\endgroup$– nicoCommented Jun 21, 2012 at 5:15
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$\begingroup$ @nico yes that's a good point, in this case it literally means sticking together $\endgroup$ Commented Jun 21, 2012 at 6:31
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$\begingroup$ I asked why people are altruistic toward those who are similar to them, and they said green beard. Then here you said green beard don't work for humans. $\endgroup$– user4951Commented Jun 21, 2012 at 12:57
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$\begingroup$ Who is 'they'? The green beard effect simply describes one possible explanation for evolution of simple cases of altruism. It may or may not apply to humans, but no human example is known. $\endgroup$ Commented Jun 21, 2012 at 13:00
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$\begingroup$ Perhaps you're talking about Winawer's answer here?. He doesn't mention humans, and specifically says it's more likely in bacteria, and that it probably isn't that widespread. $\endgroup$ Commented Jun 21, 2012 at 13:05