In the March 4th issue of Science Vol. 351 Page 1074, there is an enlightening article entitled, “The brain’s network architecture reveals human motives,” by Grit Hein (Switzerland), et al. The specific motivation that is studied here is none other than the venerable old thorn-in-the-side of classical Darwinism: *ALTRUISM*
From an accompanying article (page 1028):
To induce different motives for altruism, Hein et al. developed a clever experimental design in which a participant first interacts with two partners (who received specific instructions from the authors) in one of two scenarios. In one experimental group, a participant observes one partner receiving painful shocks, thereby eliciting an empathic response in the participant (empathy group). In the other group, a participant observes a partner sacrificing money to save the participant from receiving painful shocks, thereby eliciting a desire in the participant to return the kind behavior (reciprocity group). In both groups, the participant is also paired with a second partner who serves as a control—that is, a second person who does not receive painful shocks in the empathy group, or who does not sacrifice money to relieve the participant’s shock treatment in the reciprocity group.
Following this phase of motive induction, all participants performed a money allocation task. They chose between maximizing a partner’s monetary payoff by reducing their own (prosocial behavior) or holding on to the money at a cost to the other person (selfish behavior). During this task, the participants’ brains were scanned by functional magnetic resonance imaging (fMRI)—which uses changes in local blood flow as an indicator of neural activity changes—while they chose how to allocate the money. As expected, participants sacrificed more money to the empathy or reciprocity partner than to the control partner. Critically, this increased altruism did not differ between the groups, so that the hidden motive could not be accurately inferred from behavior alone. Hein et al. analyzed the neural data using a conventional contrast of brain activation during altruistic decisions toward the empathy/reciprocity partner versus the control partner. In line with previous work, a brain network including anterior cingulate cortex (ACC), anterior insula (AI), and ventral striatum (VS) was identified. But again, this analysis did not reveal any differences between the two motives. However, when the authors examined how these brain areas interact with each other during altruistic decisions using dynamic causal modeling (DCM), they observed a distinction. The connectivity patterns differed remarkably between empathy and reciprocity, and, by using a novel DCM-based classification technique, the authors successfully categorized participants to their motive-induction treatment (see the figure). Hence, the reasons for being gracious to someone appear to be hidden in how cortical and subcortical structures communicate with each other.
The premise of this blog is that, between the time that hominins arose from apes six million years ago and 200 thousand years ago when Homo sapiens appeared, all hominins mentally existed within a common collective consciousness resulting in an extremely high degree of empathy in which altruism was the norm. The findings in the study support this hypothesis because the neural pathway for empathetic motivation for altruism is the simpler baseline pathway, whereas the reciprocal altruistic motivation is clearly more complexly modulated and derived from it (see the figure). In the blog’s scenario, reciprocal altruism would pertain to a specific and derived form of altruism aimed at promoting fairness in line with the principal overall hominin adaptive agenda of natural selection for the productivity and fertility of relationships as opposed to the fitness of individuals.
The currently accepted paradigm for the evolution of altruism (exclusively via selection for individual fitness) is the priming effect of altruism among kin relationships due to shared “selfish” genes (kin selection), which is later supplemented by reciprocal altruism (you scratch my back and I’ll scratch yours) when evolved cognitive abilities permitted it. In order to fit these data into that scenario, one would have to assume that a fundamental effect of sharing random genes is an increase of empathy, which, in both my clinical and personal experience, does pertain (see below).
Keep in mind that the blog’s paradigm does not exclude the individual fitness paradigm, but merely assigns it a subsidiary role in human evolution.