One of the best things about being a celebrity is you get messages from other celebrities on twitter and yesterday to my delight I got a message from the fabulous HBD Chick sharing her latest thoughts on inclusive fitness since this is a topic we’ve discussed in the past.  Most people have to go to HBD Chick’s blog to see her opinions, but when you’re a celebrity, HBD Chick comes to you.  Not that I consider my fame to be in the same league as HBD Chick’s (who get’s referenced by some of the most iconic figures in society, including Charles Murray who I saw referencing her on twitter the other day).

Now when a celebrity sends you a message, you want to respond immediately but unfortunately I can only access twitter from my home computer and I’ve been away from home a lot lately, but seeing as we’re both celebrities, I’m sure she’ll understand.

Now here’s what she writes about inclusive fitness:

there’s some amount of confusion out there in the hbd-o-sphere (and beyond!) about inclusive fitness, which is understandable since the concept is not that straightforward — especially for those of us who are not scientists. i thought it’d try to dispel some of that misunderstanding by sharing my layman’s understanding of the concept — i think i grok the idea pretty well now (in a basic sorta way) — hope i don’t add to the confusion!

Notice the humility in HBD Chick’s tone.  Us celebrities learn early that it’s always good to be humble, because our fame and the authority that comes with it attracts a lot of jealousy, and anger from those who think us unworthy of the power we wield.  Being a woman in a male dominated science field, HBD Chick likely faces additional resentment, but the high social IQ of the female brain makes her especially aware of it, and able to deflect it.(UPDATE FEB 7, 2015: HBD CHICK IS NOT A SCIENTIST AND DOES NOT HAVE A STEM BACKGROUND, BUT MY POINT WAS SHE BLOGS ABOUT SCIENCE RELATED FIELDS. HBD CHICK TELLS ME SHE HAS NEVER EXPERIENCED ANY SORT OF RESENTMENT OR HOSTILITY FROM MALE COLLEAGUES OR ANY ACTUAL SCIENTIST SHE KNOWS.)

She continues:

to start with, inclusive fitness is NOT some sort of biological law that organisms (including humans) will automatically be altruistic towards other individuals with whom they share a lot of genes (or vice versa if vice versa). if you hold that idea — and i get the impression that a lot of people do — get it out of your mind right now! you’ll feel better for it, trust me.

inclusive fitness is simply a concept or model which explains HOW certain social behaviors — especially altruism — might’ve evolved at all. period. full stop…

She goes on to say:

….everybody gets half of their dna from each of their two (for now, anyway) parents. but we also share dna with siblings and (blood-related) aunts and uncles and (wait for it…) cousins. given this inheritance pattern, probability says, for instance, that, in a randomly mating population, an individual should share 12.5% of their dna with a first cousin. so, if an individual with certain “genes for altruism” behaves altruistically toward their first cousins, odds are not bad that those first cousins might also have those same “genes for altruism.” here, then, we have a mechanism for how apparently self-sacrificing social behaviors can be selected for: since the altruistic individual 1) aids close kin with whom he shares much of his dna AND 2) probably in many instances shares the same “genes for altruism,” his being altruistic toward those kin 1) does not reduce his fitness AND 2) the “genes for altruism” get selected for, too. mystery solved. (see also: kin selection.)

I think most of us would more or less agree with what HBD Chick is saying.  But then one of my other celebrity friends Jayman makes an appearance in the comment section of HBD Chick’s blog.  It’s always a thrill for the little people when one of us celebrities shows up in the comment section of random blogs with the commoners.  I try to do it at least once a week, just to show you regular folks I haven’t forgotten where I came from.  Here’s what Jayman writes:

No description of inclusive fitness would be complete without Hamilton’s rule (lifted from Wikipedia):

rB > C


r = the genetic relatedness of the recipient to the actor, often defined as the probability that a gene picked randomly from each at the same locus is identical by descent.
B = the additional reproductive benefit gained by the recipient of the altruistic act,
C = the reproductive cost to the individual performing the act.

When this is inequality is true, the altruistic trait is selected for.

This formula, along with this table of the coefficient of relationship between human relatives (also lifted from Wikipedia):

Degree of
relationship Relationship Coefficient of
relationship (r)

Inbred strain 99%
0 identical twins; clones 100%[4]
1 parent-offspring[5] 50% (2^−1)
2 full siblings 50% (2^−2+2^−2)
2 3/4 siblings or sibling-cousins 37.5% (2^−2+2⋅2^−4)
2 grandparent-grandchild 25% (2^−2)
2 half siblings 25% (2^−2)
3 aunt/uncle-nephew/niece 25% (2⋅2^−3)
4 double first cousins 25% (2^−3+2^−3)
3 great grandparent-great grandchild 12.5% (2^−3)
4 first cousins 12.5% (2⋅2^−4)
6 quadruple second cousins 12.5% (8⋅2^−6)
6 triple second cousins 9.38% (6⋅2^−6)
4 half-first cousins 6.25% (2^−4)
5 first cousins once removed 6.25% (2⋅2^−5)
6 double second cousins 6.25% (4⋅2^−6)
6 second cousins 3.13% (2^−6+2^−6)
8 third cousins 0.78% (2⋅2^−8)
10 fourth cousins 0.20% (2⋅2^−10)[6]

…demonstrates why “ethnic genetic interests” do not exist. Ethnocentrism cannot evolve via kin-selection because the coefficient of relationship falls off so much once you go past 2nd cousins.

However the late scientist J. Phillipe Rushton (who I also knew) would disagree strongly with Jayman’s last paragraph, and argues that racism and ethnocentrism evolved to enhance our genetic fitness and that “in comparison to the total genetic variance around the world, random co-ethnics are related to each other on the order of first cousins”

I don’t know enough about genetics to know whether Jayman’s right or Rushton’s right, but it would seem logical to me that people evolved to be nice to people who look like themselves or their relatives, because (1) people who look like you have a better chance of being related to you, and (2) even if they’re not related to you, they still share some of your genes.

I also don’t see why there wouldn’t be genes for certain traits (i.e. skin color) that might cause people to be especially nice to others with the same trait even if they’re not especially related or related at all.  This is known as the green beard effect, where a certain allele causes (1) a green beard, and (2) a tendency to be nice to others who have green beards.  If everyone with a green beard had a tendency to help one another, then pretty soon alleles for green beards would replace alleles for beards of other colours that were not associated with such behavior.  And those with green beards would not have to sacrafice themselves to help other green bearded strangers, but simply helping someone get a job to support a family or other acts of friendship would be enough to enhance the probability of other green bearded people passing on their green bearded alleles.

I’ve long noticed that best friends tend to look alike, have similar heights and body types.  I’ve even speculated that green beard effect might explain why suspected alleles for homosexuality might persist despite leading to low reproduction.

Rushton has assembled enormous evidence that people tend to befriend and mate with others who resemble themselves, especially on the most heritable traits, even on the most unexpected of traits like the size of ear lobes, and a lot of these traits could be ethnic too.

Another mechanism by which ethnocentrism could have evolved is group selection, but HBD Chick is skeptical, writing in the comments:

there’s no good evidence for group selection in humans, and the population geneticists (like greg cochran) say that the math doesn’t work. also, to date, none of the pro-group selection arguments that i’ve seen have included the math for individual selection — which makes me think that they are probably overlooking it (individual selection).



However I’ve been personally told by a highly competent scientist that group selection is indeed quite plausible, though even competent scientists can be wrong.