Physicist Isaac Newton once said of the importance of his scientific accomplishments: "I could only look so far because I was standing on the shoulders of giants." By that he meant that he was relying heavily on the knowledge of his predecessors, and only by doing so could get to his own findings.
Consider for yourself how many things you use in your everyday life - how you live, how you move, how you communicate with others, what you eat - and how much knowledge you have accumulated in the course of your life. How easy would it be for you to make these things yourself through independent learning, or to acquire this knowledge only through your own observations and experiences?
Even the manufacture of a seemingly simple thing like a pencil would be impossible for us without any further cultural technology, or could only be done by a massive expenditure of time and energy. Even something as simple as a cloud, without access to the accumulated cultural knowledge of the generations before us, would be a strange creature living in the sky. Maybe our own lifetime would not be enough until we finally made a single pencil. Surely, from our own daily observations, we would hardly realize that clouds are made of water vapor.
So a peculiarity of human culture seems to be that a person born today could not invent many of the important technologies during his life and acquire important knowledge through his own experience. Based on this fact, anthropologists distinguish human culture from the culture of other species. They call this form of culture cumulative culture, from the Latin cumulare, which means as much as "accumulating", "piling up".
Anthropologists think that the cumulative culture of humans is made possible because of an increased capacity for social learning and teaching in our species, as well as an increased ability to innovate. Other species, especially primates, also pass on many behaviors through some form of social learning. However, in our species these skills were especially tuned and elaborated. This allows new ideas, new knowledge, new technologies to spread in our populations. Others in the population, in turn, can build on this knowledge and technologies, expand, enhance, and add new things. All this in turn is passed on to everyone in the population, and so on.
However, not all knowledge, technologies or behaviors that appeared in the populations of our ancestors were being passed on and accumulated to the same degree. Some of these things were copied or transmitted more than others, some things disappeard again. This is called cultural evolution.
Michael Tomasello (former Director of the Research Group for Comparative and Developmental Psychology at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany) talks about the importance of cumulative culture in our species and uses the metaphor of a ratchet.
How could we test the hypothesis that accumulated cultural knowledge was and is essential in the evolutionary success (survival, reproduction, population growth) of our species? After all, it would be unethical to run an experiment in which we deprive a group of humans of cultural knowledge and then compare them to another group of humans that has been taught a lot of knowledge and skills, to see who survives better and has more offspring in a particular environment.
What we can do is look for "natural experiments" throughout history of human groups being cut off from cultural knowledge that would allow them to survive in a particular environment. Evolutionary anthropologist Joseph Henrich has collected a number of such stories. They tell us about the importance to our survival of social interactions and transmission of accumulated cultural knowledge through teaching and learning.
Causal map on cumulative culture
What might be the additional role of group size, or the number of humans interacting, in allowing the transmission and accumlation of cultural knowledge?
How could we add the factors "Group size" or "Social network size" to the causal map on cumulative culture?
- Boyd, R. T., Richerson, P. J., & Henrich, J. (2011). The cultural niche: Why social learning is essential for human adaptation. Proceedings of the National Academy of Sciences, 108(Supplement_2), 10918–10925. https://doi.org/10.1073/pnas.1100290108
- Dean, L. G., Vale, G. L., Laland, K. N., Flynn, E., & Kendal, R. L. (2014). Human cumulative culture: A comparative perspective. Biological Reviews, 89(2), 284–301. https://doi.org/10.1111/brv.12053
- Henrich, J. (2016). The Secret of Our Success. How Culture Is Driving Human Evolution, Domesticating Our Species, and Making Us Smarter. Princeton, Oxford: Princeton University Press.
- Muthukrishna, M., & Henrich, J. (2016). Innovation in the Collective Brain. Philosophical Transactions of the Royal Society B: Biological Sciences, 371(1690), 20150192. https://doi.org/10.1098/rstb.2015.0192
- Whiten, A., & van Schaik, C. P. (2007). The evolution of animal “cultures” and social intelligence. Philosophical Transactions of the Royal Society B-Biological Sciences, 362(1480), 603–620. https://doi.org/10.1098/rstb.2006.1998
- Whiten, A., Hinde, R. A., Laland, K. N., & Stringer, C. B. (2011). Culture evolves. Philosophical Transactions of the Royal Society B: Biological Sciences, 366(1567), 938–948. https://doi.org/10.1098/rstb.2010.0372