The evolution of out-group altruism in Homo Sapiens via a dual kin selection/reciprocal altruism and group selection mode

Evolutionary psychologists and biologists have long puzzled over the phenomenon of altruism. Altruism has long been thought to have been arisen by kin selection, but  kin selection can explain true altruism up to several levels of genetic relatedness. Some people are clearly more altruistic than others and don’t only display in-group altruism, but also outgroup altruism. How could this kind of altruism have arisen, when it is so easy for altruistic genese to get hijacked by parasites?

FIrst let's track down potential genes for altruism.  In my mind, the most promising candidate is the OXTR gene (oxytocin receptor) rs53576 with its three genotypes GG, AG and AA. 

The following table provides a genetic study of allele frequencies.

		Frequencies
		Allele			Genotype
rs53576
Population	Number	A	G	Number	AA	AG	GG
African All*	1194	0.224	0.776	597	0.057	0.333	0.610
Americans of African Ancestry in SW USA	122	0.287	0.713	61	0.082	0.410	0.508
Luhya in Webuye, Kenya	198	0.211	0.789	99	0.052	0.320	0.629
Yoruba in Ibadan, Nigeria	216	0.193	0.807	108	0.045	0.295	0.659
Hadza, Tanzania	270	0.426	0.574	135	0.148	0.556	0.296
Datoga, Tanzania	388	0.302	0.698	194	0.077	0.448	0.474
American All*	524	0.343	0.657	262	0.116	0.453	0.431

The Hadza and Datoga are highlighted, because they have very different social organizations. The Hadza are monogamous, egalitarian hunter-gatherers (most frequent allele AG), whereas the Datoga are stratified, polygynous pastoralists (GG dominant) and personal wealth clearly correlates with reproductive success.The Dagota are more in-group cooperative and more kin-selected/reciprocal altruism type, who show a high degree of verbal and physical aggression (also towards women), whereas the Hadza are more out-group cooperative (hospitable) and more group-selected.

What is interesting to note, is that the relatively rare AA type can thrive only in a population with higher AG types. Else, there would be a high chance of GG parasitising AA. Surprisingly the AA type is often described als less empathetic than the other two groups (with AG being the most pro-social). Even though the AA type is typically described as less empathetic (and that is what makes things a bit confusing), my hypothesis is that the AA types are the true altruists? How is this possible?

Let’s have a look at the conditions under which true altruism can arise in group selection.

Randolph Nesse writes in his wonderful book “Good Reasons for Bad Feelings: Insights from the Frontier of Evolutionary Psychiatry” (2019)

“However, alleles for such [altruistic] tendencies can persist only when three special circumstances are met: groups with more cooperative individuals must grow much faster than groups with fewer cooperative individuals; individuals with alleles for helping must reproduce only a little less than others in the group who do not have such alleles; and finally, exchanges of individuals between the groups must be limited, otherwise non helping individuals will move into the group and their alleles will displace the ones for helping. These conditions rarely occur together. Group selection of this kind is weak and unable to explain costly traits. An essay by Steven Pinker explains why in crystal-clear detail.

I think there is one personality type that corresponds well to these conditions: introverted rationals and idealists. Their deep introversion and thinking is the mechanism that keeps them separated from the kin selected GG (in-group sociality) genotypes. They typically mate with extraverted Intuitives or introverted Sensors (presumably AG type). So the AG genotype acts as a buffer against potential GG parasites. AG generally can mate with both types.

How are AA beneficial to the group? Already Darwin hypothesised that extremely innovative individuals could benefit the group in extremely harsh conditions. Of course, this is only possible with a sufficient number of AG genotypes, who are willing to support the AA types. The most innovative personality type in Myers-Briggs terminology are INTX (although only 5% in the general population they make up the majority of Nobel laureates and 20% of all the people who work at Google). INTPs usually keep away GG not only by their apparent introversion, but also by their brutal honesty, which tends to hurt GG type feelings more than other AA types or AG types (e.g. telling a GG that country music sucks).

INTX types have reduced social cognition (memory for names, faces, are bad at recognizing emotions, etc.) in favour of increased general cognition (problem solving skills).

To name an example: Richard Dawkins (INTP, AA type) fights for scientific truth and is like most scientists not very motivated by financial reasons. AA types highly depend on the group for their survival, so their greatest pay-off is measured in social appreciation and integration and less in status symbols and financial rewards. This social recognition is the reason why most university professors share their findings for free and sometimes even pay for publication. Richard Dawkins hates traditions and wants to show people how they are blinded by their religious believes.  GG types, however, find innovation and reason much less important than social cohesion and feel threatened by Richard’s atheism, as religion is one important mechanism to keep their community together. By blatantly offending the GG types (without evil intentions), Richard makes sure his circle of friends only consists of other AA and AG types.

A second group of AA types are actually very empathetic. INFX types also have the very same reduced social cognition, however they use their general cognition on social matters and are extremely good at mediating severe conflict in the group even though they usually avoid most minor types of conflict because they incur high emotional costs (stress) on them. 

AA types are highly innovative individuals who sacrifice social cognition in favour of general cognition (zero interest in gossip and small talk, forget names, even risk autism, ADHD and prosopagnosia). Such a genotype can only thrive if the individual is integrated and appreciated for their innovative social contributions. If this is not the case these individuals develop a host of mental problems ranging from ASD, ADHD to depression and self-harming tendencies. This is exactly what we see with ASD and gifted orchid children who fade away. At a time when deep social connections are becoming increasingly rarer AA/AG types are bound to suffer from all kinds of mental illnesses.

To summarize: Group selected altruism increased during extremely difficult conditions in human history (think of the permanently persecuted Jewish people, who have high occurrences of AA/AG types and therefore innovative potential) and have a number of partial separation strategies:

• Introversion (makes them more cautious and reflective in social interactions)
• Heightened sense of (out-group) justice to detect intruders and protect each other
• Boost to general intelligence (at the cost of social cognition) to detect intruders, be innovative in times of hardship and to resolve conflicts in times of social crisis. 
• A buffer group (AG types probably extraverted intuitives and introverted sensors)
• Delayed onset of reproduction
• Typically invest more resources in fewer offspring than GG type.
• Potentially longer lifespans (reduced dopamine in introverts) 

Dedicated to my intuitive friends, Elke, Fabiana and Marius

Dedicated to Randolph Nesse and Steven Pinker, two of my heroes in Evolutionary Psychiatry and Evolutionary Psychology