A Story of Us: A New Look at Human Evolution
Oxford University Press, NY, NY, 2021
304 pp. Trade, $29.95
A Story of Us by Lesley Newson and Peter Richerson is a smart and engaging book by two seasoned thinkers and scientific writers. For an academic work the book is lucid with a pleasing narrative. I’m reminded of other strong writing teams, like Ann Druyan and Carl Sagan (Shadows of Forgotten Ancestors). The reference to Sagan is appropriate since Newson and Richerson include, like Sagan in chapter seven of his acclaimed book Cosmos, an account from the perspective of a human ancestor. The stories embedded in each chapter by Newson and Richerson are ingenious, appealing, and reflect the solid scholarly material presented simply and directly before and after any given story. All the pieces fit together nicely. Newson and Richerson’s book is enjoyably readable and profoundly informative about the power of cultural evolution. I’d recommend this book to students of the human career, to borrow from paleoanthropologist Richard G. Klein, and especially to college instructors across disciplines using the word “culture” in their course descriptions. In this way they would better understand what culture encompasses, how it evolved through human history, and its continuity and discontinuity with our recent and distant ancestors.
In their title, Newson and Richerson emphasize “us” because human thinking and enterprise succeed via social learning and cultural networking. As cultural evolutionists, I wonder if their title is a response to Joseph Henrich’s book, The Secret of Our Success. Henrich shamelessly touts how humans are supremely unique by having dominated nature. While Newson and Richerson lean in that direction, they are more realistic about the fluctuations in human prehistory and the questions about our future on the horizon. There is no special ingredient to being human; there is no human nature. Rather, what differentiates us from other species (a word they eschew) is our ability to evolve culturally, which can be rapid as opposed to the gradual changes that occur through natural selection. Philosopher of science Tim Lewens, in his book Cultural Evolution, would say that Newson and Richerson are more to population systems as opposed to evolution via genetic inheritance. Of course genes respond to environment, so chemical DNA is part of the equation; but any given population, indeed the compounding of multiple populations, consists of an “environment” that can trigger genetic response.
The book is neatly divided into eight chapters, and each chapter takes us through a different period of human history. Their subtitle claims the book is a “new look” at human evolution since leverage is placed on cultural evolution in and across groups. They are less concerned about genetic variation and inheritance through individual selection. As part of each chapter, there is a story that narrates what someone of that time would think, feel, and experience on a visceral and communal level. We start with ape ancestors to highlight the mother-infant bond and food foraging. From time to time, beginning here, the authors reference the human brain and how in size it’s larger than that found in living great apes. Carefully, they do not suggest that one species is necessarily better than any other. Rather, there could be adaptive peaks, and apes evolved to fill their ecological niche in ways that early hominins did not. We pretty much left the forest behind. Their discussion of Ardipithecus and Australopithecus, some of the early ancestral relatives of humans, is clear and easy to understand as they take readers through changes in physiology and morphology. They cover lots of territory, but importantly they stress the communal and social behavior of apes, spending most of their time on chimpanzees and bonobos, our nearest relatives. Chimpanzees are the most advanced and habitual users of tools, for instance. The upshot is, to use their terminology, “culture introduces more flexibility.” This means that ape/human behavior is influenced by the practices around them and which they inherit through family, peers, and other groups. This is echoed in the title of a book by Peter Richerson and Robert Boyd, Not By Genes Alone. Genes help bodies grow in reply to external cues, but culture helps young apes learn how to forage and for what, how to use tools to extract termites or nut foods, how to socialize, etc. These are cultural activities since field primatologists know that inherited behaviors differ among groups across various locations.
Since australopiths around three million years ago evolved bipedalism and spent time outside of the forest in the savanna, cooperative groupings and signaling would have been advantageous. Different foods are spread more widely in this environment, so alloparenting was likely used for mothers to help each other. Newson and Richerson ably explain how adaptations from natural selection were beneficial, e.g., the loss of body hair for cooling while maintaining head hair for protection from sunlight. Importantly, the hominin-child bond is weaker than that in apes to allow for shared parenting by, mostly, females. In turn, this co-dependency helped evolve with brain adaptations for successful cooperative living, less aggression, emotional expression, demonstrative control, and punishment. All of this explains cultural differences between groups. Cultural inheritance can be selective in how a youngster sees others process foods or socially behave, which is different from adaptations, like gut formation from genes. If many people (or apes) in the group vary a food processing practice, a youngster might be selective in whom to copy. In turn, this learning by imitating those most successful creates a feedback loop in the individual and group for innovation. Then, this group information is shared, copied, improved, and passed on. While cognitive genes are part of this picture (the mentality of apes, as primatologist Wolfgang Köhler would say), intelligence output is geared more to the population. Any advantageous food processing and sharing would increase survival of individuals in the group, enhancing additional cultural advances. As groups become too large, they split and move on, with a transfer of cultural knowledge that can be ratcheted up yet more.
As the chapters logically proceed chronologically, Newson and Richerson get closer to our own time. Early humans from over one million years ago are covered. Beyond competition in natural selection, humans were and still are, they insist, generally more cooperative than selfish. This supportive behavior helped early humans travel out of Africa to Asia, Europe, and farther afield. Natural selection would enter the picture here in terms of favored traits, like altruism which enabled families to thrive over highly competitive groups. Even Charles Darwin recognized this in chapter four of The Descent of Man. The authors also connect the evolution of a larger brain to early human abilities of cutting, pounding, fermenting, and eventually cooking a variety of foods. The technique of processing food so that it is, essentially, predigested, reduced the size of our teeth and intestines in a gene/culture coevolution. However, some cultural adaptations can improve but not totally erase genetically evolved instincts. Nonetheless, cultural adaptations grew our brain which required more energy and reformed our bodies to be more gracile since we could find and refine food in ways unlike, say, a lion.
Half a million years ago we were nomadic hunter-gatherers, much like the ancestral relatives from over a million years ago. At that time, Newson and Richerson say, some of our recent cultural traditions might have begun to take shape, such as arranged marriage. There were not many humans then, compared to other animals, but their brains and culture helped people survive in ways where other creatures physically adapted. We know this since back then there were wide variations of climate temperatures, ultimately leading to ice ages. In a coevolution feedback, environmental fluctuations enabled a plastic brain to develop creative survival techniques such as cooperative group sharing of goods, services, and information, which expanded the brain yet more. By around one hundred thousand years ago there were probably more stable family structures, the authors say, with the beginnings of a division of labor and a system of justice. We are a cultural species; feelings like shame and disgust are shared across societies but expressed in different ways. Social emotions are strong motivators, important tools for any group, and why people from different cultures can ultimately assimilate into one not natively their own.
Culture is in many ways a network of brains thinking and acting alike, helping and caring for others without anticipating a reward. This is why, the authors believe, all prosocial emotions we experience are derived from our ancestors since they survived to pass these feelings to us. Culture is like genes in the sense that it wants to reproduce. People who chose not to bear the hardship of pregnancy or the responsibility of parenting did not pass on those beliefs. Rather, the people who valued family passed on what humans inherited. They note that marriage became a stable norm, successful cultural glue that was inherited and disseminated. Likewise, widening the sphere, these norms of connectivity helped groups interact, and so on.
In spite of the ice age, around thirty thousand years ago, humans were thriving across Europe, Asia, and Australia. Art culture began to appear in the fossil record, ranging from carved figures, jewelry, musical devices, and parietal art preserved in caves. Mammoth hunting would have required considerable skill and the cooperation of many. All of the dead animal’s meat, fur, and bones were used for some purpose. Culture adapted to the ice age and facilitated humans to adapt. Much more sophisticated tools appear, from spear points, nets, and hooks to needles for sewing together hide clothing and shoes. In this part of the story, some consideration is given to Neanderthals and Denisovans, early humans who died off, perhaps because of their smaller groups. At any rate, by now some of the cultural practices include spiritual beliefs and rituals containing ceremonial burial and decoration of select deceased people. In spite of the rupture between groups because of spikes in cold temperatures, Newson and Richerson say there is evidence at that time of large meetings of many groups, which would have aided the sharing and spread of theoretical and practical understanding, culture.
The story of humans takes on new shape by around ten thousand years ago. There are more tribal groups and hence conflicts, mostly, they say, because with a more stable climate there is now no “common enemy” that pulled different people together. There was less travelling and the beginning of sedentism, which implied food storage along with animal and property ownership. Competition for possessions would have affected cultural models. People were learning about new ways to produce different foods and experimented with growing crops. Tribal competitions and the demonizing of out-group people would be cultural. We seem to have inherited, they say, this fear of and bias toward others through a closely knit culture we tend to favor. Familiarity would ensure the transmission not only of possessions, property, and family values and traditions but of genes into future generations. Culture in some way creates an environment to which our genes respond. For example, more restricted diets evolved through agriculture, and our genes, in part, evolved and were driven by this agricultural change. Take, for instance, the example of lactose tolerance in adults. Lots hinges on what is copied and how well genes or cultural beliefs and practices benefit. In this regard they offer a wonderful discussion of languages related to migrations across the Near East and into Western Europe. At that time, quite a bit of cultural practices were colliding, related to cereal farming and herding, where the herders seem to have gained an advantage.
Their story ends in modern times, and they note that now there are many choices open to an individual. This means that one does not necessarily have to accept, as in the past, the beliefs and practices of the family but can diverge and, in essence, move into another group with different values. In fact, we see that in how some children spin off from their families not out of disdain but simply because of vastly different cultural outlooks. Take for instance marriage: what constitutes or defines marriage today? We see in many modern cities various enclaves of different cultures living peacefully side-by-side, though not at times without tensions. The authors seem to suggest that low birth rates in the modern period, dating back to the eighteenth century, accompany dramatic cultural changes where the old order is questioned. Variations in human behavior, like fertility rates past and present, are transmitted mostly by culture.
Newson and Richerson remain optimistic about the future of humans because of our flexibility to adapt culturally. Their book is a delight to read and will be informative to many students and scholars across disciplines about the social dimensions of evolutionary change. Readers will no doubt remember best the compelling interpolated stories which mirror the impeccable research.