The authors say:
biological altruism cannot be conceived as arising from a process of gene–culture coevolution...and...
Culture does not change the selective pressure on genesOn the face of it, these statements are completely mistaken. What is going on with these authors? They say:
cultural evolution solves the problem of altruism only to convert it into another problem: the fact that individuals learn from others in a way that eventually leads them to acquire maladaptive behaviours.
We already understand this second "puzzle", though. Cultural transmission is adaptive overall - or at least it has been historically. It's what has enabled humans to conquer the planet. It does sometimes lead to humans acquiring maladaptive behaviours - but that's the price you pay for a package that has been positive overall, so far.
The paper is mainly concerned with trying to to make sense of the literature on cultural group selection. The paper argues that much of this literature is rather muddled. That is something that I can agree with.
The paper insists that altruism resulting from cultural transmission must be maladaptive from the perspective of the host.
However, just because something is bad for an agent, that doesn't necessarily mean that it will be bad for populations containing those agents. The classic example of this is smallpox. Smallpox isn't good for you when you get it. However populations carrying smallpox conquered the world - systematically obliterating populations without smallpox. This was no accident - the European colonists won, in part, because they were smallpox carriers.
Culturally-mediated cooperation that harms donors could be like that - causing individual harm and group benefit simultaneously.
The authors close with an argument that altruism caused by cognitive mistakes (e.g. heuristics) is a lot like altruism caused by cultural transmission - which the authors treat as another way of making cognitive mistakes. There's certainly some similarity there.
However, I would point to a significant difference: with most cognitive mistakes, there's no opponent. No other agent is actively trying to manipulate you into making those mistakes. With cultural transmission, though, agents face an evolutionary process with a conflicting optimization target and a rapid pace. Meme evolution is actively working against their own interests - memes are working to get them to make mistakes. This results in significant differences between the dynamics of the processes involved. This is part of the reason why meme-based hypotheses are more fertile as sources of cooperative behaviour than hypotheses involving cognitive resource limitation or over-generalization.