Editing Kin selection (section)

=== Kin recognition and the green beard effect===

[[File:BeardGreen.jpg|thumb|upright|[[Kin recognition]] theory predicts a selective advantage for the bearers of a trait (like the fictitious [[Green-beard effect|'green beard']]) behave altruistically towards others with the same trait.]]

First, if individuals have the [[kin recognition|capacity to recognise kin]] and to discriminate (positively) on the basis of [[kinship]], then the average relatedness of the recipients of altruism could be high enough for kin selection. Because of the facultative nature of this mechanism, kin recognition and discrimination were expected to be unimportant except among 'higher' forms of life. However, as molecular recognition mechanisms have been shown to operate in organisms such as slime moulds <ref>{{cite journal |doi=10.1038/ncomms8144|last1=Ho |first1=Hsing-I |last2=Shaulsky |first2=Gad | journal=Nature Communications |volume=6  |pages=7144 |year=2015 |title=Temporal regulation of kin recognition maintains recognition-cue diversity and suppresses cheating. |doi-access=free |pmid=26018043 |pmc=4448137 |bibcode=2015NatCo...6.7144H }}</ref> kin recognition has much wider importance than previously recognised. Kin recognition may be selected for inbreeding avoidance, and little evidence indicates that 'innate' kin recognition plays a role in mediating altruism. A thought experiment on the kin recognition/discrimination distinction is the hypothetical [[Green-beard effect|'green beard']], where a gene for social behaviour is imagined also to cause a distinctive phenotype that can be recognised by other carriers of the gene. Due to conflicting genetic similarity in the rest of the genome, there should be selection pressure for green-beard altruistic sacrifices to be suppressed, making common ancestry the most likely form of inclusive fitness.<ref name="Hamilton 1964 1–16"/><ref name=Grafen>{{cite journal |last=Grafen |first=Alan |title=Green beard as death warrant |journal=[[Nature (journal)|Nature]] |volume=394 |pages=521–522 |date=6 August 1998 |url=http://users.ox.ac.uk/~grafen/cv/grbeard.pdf |doi=10.1038/28948 |issue=6693 |s2cid=28124873 |doi-access=free }}</ref> This suppression is overcome if new phenotypes -other beard colours- are  formed through mutation or introduced into the population from time to time. This proposed mechanism goes by the name of 'beard chromodynamics'.<ref>{{cite journal |doi=10.1038/nature04387|last1=Jansen |first1=Vincent A.A. |last2=van Baalen |first2=Minus | journal=Nature |volume=440  |pages=663–666 |year=2006 |title=Altruism through beard chromodynamics. |issue=7084 |pmid=16572169 |bibcode=2006Natur.440..663J |url= https://www.nature.com/articles/nature04387}}</ref>