If it were all due to biology, wouldn’t behaviour in different cultures be more similar? (comment by @MReyesZam)

Cultures are very similar within specific dimensions (reproductive mechanisms, care for young offspring, ways to obtain status, ways of feeding, etc.) and, as we approach specific, concrete aspects, they start to become more different. Biology does not contradict this. If we think of some wild animal (sparrows, brown bears, bullfrogs…), actually, we see that the behaviours of animals, which are determined in important ways due to their biology, are very diverse, when examined up close, of course. From further afar they are very similar (within the dimensions mentioned above, for example). That is to say, the importance of biology does not imply a reduction in variability of concrete aspects; those that are less variable are general aspects within a species.

One can observe this by analysing, at an individual level, the biological determinants that give us an indication of biological determination and variability. On the one hand we have the presence of alleles that determine our behaviour in a specific way (for examples see Soliman 2010; Tost 2010; Wallum 2008), which we do not all carry, and on the other, the genetic effects on behaviour, which often explain 50% of observed variability (Zietsch 2012; Rhee 2002; Ebstein 2010). Finally, we have the effect of hormones on behaviour, which reaches different levels in different people (Hines 2003; Kosfeld 2005; Ebstein 2012; Eisenegger 2010; van Honk 2012).

Aside from this, there are a series of features that appear in all cultures and are called cultural universals (there have been efforts to compile these, which is a topic of much debate, but there is a good collection of them in a book by D.E. Brown entitled Human Universals). The reason for these similarities could be evolutionary convergence, of course, but from my point of view it is more plausible that it may be the fact that there is a shared a common biology (as expected, there is debate about that: Brown 2004; Levy 2004). In addition, there is another series of traits in human cultures that, without being universal, are very generally present, i.e., they are present in many cultures, but not all. Two reasons for this are proposed here: the diffusion of useful cultural inventions, or the appearance in different places of identical inventions, due to the fact that we human beings often share needs and are subject to similar situations. In any case (that is, should either cause be valid), their existence lets us see that cultures are not that different.

In order to see whether something is biologically-based, analysing it within as many cultures as possible is fundamental, avoiding eurocentrism. In this sense, there are very interesting studies that show that behaviours that are absolutely frequent within a very concrete population are difficult to extrapolate to the entire species (Henrich 2010).

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