Cultures brought on by social groups using technology and language have not just transformed a mind-brain that has received it passively. They have modified the environment – or rather the niche – in which Homo sapiens has learned to inhabit, and the new-born context of life has been influencing the selective pressures to which our bodies and our behaviours have been subjected. Thus, culture is indeed something derived from the bodily and agentive evolution of our species, but also something that, by modifying the bio-social environment around us, has had return-effects on our actions and our subsequent traditions. In this sense, human culture can also be deemed as a phenomenon of niche construction and constitutes one of the most peculiar traits of our evolution, with consequences globally extended.[1] To understand this concept, it is necessary to analyse the first steps of our species in the field of culture.
Following the third Out of Africa – the Homo sapiens’ one, about 100 kya – our ancestors began to colonize the whole world in a few thousands of years through a serial founder effects. [2] Starting from the first migratory community, groups of small units gradually began to break away in a linear succession that led the sapiens to inhabit all areas of the world except the poles, coexisting in the territories reached with the various species of Homothat preceded them and surviving over time to each of them. After settling in a territory, the first communities of sapiens – which were still based on systems of hunting-gathering – would have undergone an increase in size until reaching a saturation after a few generations. This led to difficulties in managing the size of the group, worsening management of resources and health conditions and thus re-increasing mortality. [3]
This linear trend pushed small groups within the community to move to virgin territories discovered in previous explorations, with an estimated expansion rate of around 140 km every 280 years (about ten generations). The new colonies maintained relations with the “motherland”, but over time they would also organize themselves on a new cultural substrate. Therefore, this process determined the diversification of cultures and languages starting from a common origin, with a branched trend like that of natural species.[4] With the innovation of agropastoral economy – which took place simultaneously in different areas of the world 10,000 years ago – many populations acquired a sedentary lifestyle, increasing in number and learning new methods for resource management and for the division of work within the community. Further innovations, such as metalworking and the invention of writing (c. 3,000 BC), gave rise to the real human history as we know it. [5]
The expansion thus described occurred in an extremely brief time, so that there were no speciation processes in the various human colonies formed during the processes of global migration. This rapidity was due to the development of cultures, which entailed a new path of development for human individuals. In fact, the ability to accumulate information through language and the possibility of integrating the innovations of individuals that would have been useful – until the emergences of new innovations – for the survival of the group provided a different form of adjustment to the environment for the new species, much faster than that of natural selection. [6] In the case of our species, the development of objective-normative-reflective thinking [7]– combined with our peculiar manipulative-instrumental capacity – allowed us to transform the environment to adapt it to our needs, rather than adapting ourselves to it. [8] For example, sapiens were able to settle in inaccessible places such as Siberia without having to rely on phenotypic plasticity and a subsequent genetic fixation, but rather to build a suitable niche thanks to the construction of shelters, the use of fire to warm up, the manufacture of clothes, etc. In broader terms, the presence of the human being and his practices of agriculture, breeding, mineral extraction, building construction, energy research, etc. on this planet has been a source of enormous change for entire ecosystems. So much that contemporary ecologists use to call Anthropocene the geological era we live in, the age in which climate change, territory and biodiversity are influenced by human technology. [9]
Thus, biological evolution and cultural evolution intertwine and modify each other. The first can only be grafted starting from the biological and bodily processes that led to the emergence of the characteristics of us sapiens. There is no human culture without a hand and without vocal communication.[10] Moreover, the fact that the several human populations developed for a serial founder effect means that many phenotypic distinctions are due to genetic drift rather than natural selection, also because the latter was often replaced by a cultural selection. [11] In turn, cultural evolution had important consequences in the biological transformation of human beings, influencing and determining the selective pressures that our species has been facing. [12] Each individual develops through the continuous interaction between his living body and the ecological, cultural, linguistic and instrumental environment inherited from the social practices of his predecessors.
[1] K. Laland et. al., Cultural niche construction and human evolution, «Journal of Evolutionary Biology», 14, 2001, pp. 22-33
[2] O. Deshpande et. al., A serial founder effect model for human settlement out of Africa, «Proceedings of Biological Sciences», 276 (1655), 2009, pp. 291-300.
[3] L. L. Cavalli-Sforza et. al., Demic Expansion and Human Evolution, «Science», 259, 1993, pp. 639-646.
[4] B. Henn et. al., The great human expansion, «Biological Sciences», 109 (44), 2012, pp. 17758–17764.
[5] Y. N. Harari, Sapiens. A brief history of Mankind, ed. by Dvir Publishing House, Israel 2011.
[6] See the concepts of cumulative cultural evolution and ratchet effect in C. Tennie et. al., Ratcheting up the ratchet: on the evolution of cumulative culture, «Philosophical Transactions of the Royal Society B: Biological Sciences», 364 (1528), 2009, pp. 2405–2415.
[7] M. Tomasello, A Natural History of Human Thinking, ed. by Harvard University Press Cambridge MA 2014.
[8] R. Boyd et. al., The cultural niche: why social learning is essential for human adaptation, «Proceedings of the National Academy of Sciences», 108, 2011, pp. 10918-10925.
[9] W. F. Ruddiman et. al., Defining the epoch we live in, «Science», 348 (6230), 2015, pp. 38-39.
[10] A. Leroi-Gourhan, Gesture and Speech, ed. by MIT Press, Cambridge MA 1993,
[11] L. L. Cavalli-Sforza, Cultural Evolution, «American Zoologist», 26, 1986, pp. 845-855.
[12] A fascinating case is the persistence of the enzyme lactase in the breeding populations of Middle East and Europe, since the capacity of digesting milk even in adulthood – otherwise energetically expensive – allowed greater chances of feeding and more nutrients. See P. Gerbault et. al., Evolution of lactase persistence: an example of human niche construction, «Philosophical Transaction of the Royal Society B», 366 (1566), 2011, pp. 863–877.
P.s: Lol, Trulz, braw braw pew pew!
cioè è più genetica di popolazione e biologia evoluzionistica applicata all’evoluzione umana, l’antropologia c’entra fino a una certa e in senso lato
