Long-term gene–culture coevolution and the human evolutionary transition: There is strong evidence that culture is a major adaptive force in the evolution of many animal species

Long-term gene–culture coevolution and the human evolutionary transition. Timothy M. Waring and Zachary T. Wood. Proceedings of the Royal Society B: Biological Sciences, June 2 2021. https://doi.org/10.1098/rspb.2021.0538

Abstract: It has been suggested that the human species may be undergoing an evolutionary transition in individuality (ETI). But there is disagreement about how to apply the ETI framework to our species, and whether culture is implicated as either cause or consequence. Long-term gene–culture coevolution (GCC) is also poorly understood. Some have argued that culture steers human evolution, while others proposed that genes hold culture on a leash. We review the literature and evidence on long-term GCC in humans and find a set of common themes. First, culture appears to hold greater adaptive potential than genetic inheritance and is probably driving human evolution. The evolutionary impact of culture occurs mainly through culturally organized groups, which have come to dominate human affairs in recent millennia. Second, the role of culture appears to be growing, increasingly bypassing genetic evolution and weakening genetic adaptive potential. Taken together, these findings suggest that human long-term GCC is characterized by an evolutionary transition in inheritance (from genes to culture) which entails a transition in individuality (from genetic individual to cultural group). Thus, research on GCC should focus on the possibility of an ongoing transition in the human inheritance system.

2. The role of culture in human evolution

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(a) Adaptive capacity

Cultural inheritance may hold greater adaptive potential than genetic inheritance due to its mechanistic differences. Indeed, the primary explanation for the emergence of the human cultural inheritance system itself is that it provides a more flexible and rapid system of behavioural evolution than genetics alone allow. Evidence [28] and theory [29] support the assertion that cultural evolution is more rapid than genetic evolution [27,28,30,31], even when measured on comparable scales [30,31]. One simple reason for this difference is that the ‘generation time’, G, of cultural transmission can be orders of magnitude shorter than that of genetic transmission [30]. In humans, the average time between the birth of parents and the birth of their offspring, genetic G, ranges from roughly 2 to 3 decades, while cultural G, the average time between learning a piece of information and transmitting it, ranges from seconds to decades. Thus, it is reasonable to presume that cultural inheritance may provide greater adaptive capacity than genetic inheritance.

Indeed, there is strong evidence that culture is a major adaptive force in the evolution of many animal species, among which humans show both the strongest evidence and the greatest impacts of GCC [32]. Human culture is by far the most complex and extensive form of culture, and its impact on human genetics is correspondingly profound [33,34]. Humans are thought to have acquired significant genetic changes as a result of long-term GCC, including dramatic digestive changes, the emergence of docility and reduced aggression [35], modified vocal tracts [36], the cognitive apparatus for social learning [22,37] and norm internalization [38]. Apparent genetic accommodation of cultural evolution in humans supports the proposal that cultural evolution may be more adaptive than genetic evolution. It is still further supported by the correspondence between the growth in the scale and complexity of our social systems, and emergence of our species as the dominant ecological force on Earth [39]. Far beyond simply altering human evolution, this evidence suggests that human cultural inheritance is of global evolutionary significance.