Biologist Kevin Laland has a gift for clear, evocative writing and clever titles. An "unfinished symphony" is a powerful metaphor, hinting at the lost works of departed geniuses. Perhaps no post-Enlightenment figure has had as profound impact on how humanity sees itself than Charles Darwin, and the chance to extend the modern evolutionary synthesis to incorporate an account of the origins of human culture and intelligence creates possibilities that will be euphoric for some readers and terrifying for others. Laland's book contributes to an emerging corpus of recent literature aiming to close the enormous gap that has opened up between the biological and social sciences.
Laland is not a historian, and those looking for a compelling account of Darwin's research on the origins of humanity should look elsewhere. "On the Origin of the Species" is famously silent on the question of human origins, and Darwin's later works on the subject ("The Descent of Man" and "The Expression of the Emotions in Man and Animals") are less well known and more heavily weighed upon by the passage of time. For Laland, Darwin's 'unfinished symphony' was the task of explaining humanity's unique mental, cultural and moral capabilities in light of evolution, and the subtitle of his book ("How Culture Made the Human Mind") gives the game away in terms of where Laland suggests the answers will be found. This is also the story of a thirty year effort by Laland and his team to find those answers: an ode to grad students and published research most of the public have never heard of.
The boundary between biological and social evolution is fiercely patrolled on both sides, with many biologists stressing that evolution only applies to genetically-encoded behaviours (c.f. Dawkins) and many sociologists epistemologically wedded to the unnatural uniqueness of human culture. We can perhaps refer, as Laland does, to cultural evolutionary studies pioneered by Boyd & Richerson among others, which has been a remarkably successful effort to apply evolutionary tools to the study of culture. Laland, however, goes beyond that to write a book focused on gene-culture coevolution. That is, a study of how genes have influenced culture and culture, in turn, has influenced our genes. Evolutionary psychologists and behavioural economists have made strides (often flawed) into measuring biological influences on human behaviour, in the process contributing to a resurgence of naturalist ethical ideologies. Laland's position is more nuanced: our biological intuitions and mental capabilities have developed in a feedback loop to meet the needs of humanity's complex learning behaviours.
Innovating and Copying
As a mechanism which develops and spreads new traits through a population, culture relies on the innovation of new behaviours (beyond what is encoded in a creature's genes) and the copying of that behaviour by others (which allows it to spread faster than biological transmission alone would allow). Social learning is innate and ubiquitous among humans and - it turns out - not entirely unknown amongst animals. Crucially, Laland is able to demonstrate through both mathematical models and empirical studies that what matters to the cultural capacity to accumulate fitness-enhancing improvements over time is not just copying but copying efficiently, faithfully and strategically. Learning heuristics such as imitating successful individuals or conforming with the behaviour of the majority ensure that useful information is retained over generations, and it's this capacity for strategic or contingent learning that Laland argues lies at the root of the divergence between humanity and other animals.
Laland combines agent-based computational models of social learning with empirical studies of social learning in animals, most amusingly fish. Throughout the early chapters of the book, he builds a compelling case for why social learning is not ubiquitous in nature, noting that vulnerability to predation and the demands of reproduction make some species (and some individuals within species) more reliant on social learning than others. In Laland's observations, it's often lower-status individuals, females and children that benefit most from openness to new experiences and social learning. A certain conservative Canadian psychologist has recently invited derision by looking for the origins of social hierarchies amongst lobsters. Laland's fish studies are different because his team has gone to the effort of first proving that social learning is a mathematical solution to a general category of problem: humans are 'like fish', in this sense, because both evolved similar strategies to solve analogous problems, not because we share some biochemistry. A more sophisticated version of Jordan Peterson might be able to do the modelling to show that hierarchies are a valid solution to the problem of cooperation - but unlike Laland, Peterson simply hasn't done his homework.
More than just the evolution of intelligence
Unlike other pop science authors, Laland's descriptions of his statistical methods and techniques are always clear and precise - we always know how much confidence we should have in Laland's conclusions and how they're derived. Where that raised an eyebrow, however, was when Laland moved away from discussing social learning to the evolution of intelligence. Laland relies on a variant of factor analysis to argue for the existence of what he calls the "primate g", a measure of the general intelligence of primates which he argues has increased alongside the demands for increasing social learning. In this way, Laland aligns himself with the view that intelligence is an all-purpose tool that has continually improved throughout human evolution, rather than an agglomeration of modules and capabilities which arose at different points in our species' history in response to different environmental and social requirements.
Ultimately, Laland's efforts to downplay the 'social brain' hypothesis are unconvincing and I would recommend Robin Dunbar on these topics. Is a 3cm long fish that finds a novel solution to a food maze really 'innovating', or it merely following instincts that drive hungry individuals to take greater risks? It's likely that general intelligence is a poor tool for solving most social games among humans, at least, (cf. the ultimatum game) and IQ is a poorer predictor of social status than modular personality traits. The role of emotion and motivated action is missing from Laland's account, an omission that's curious given that Darwin himself intuited that the evolutionary function of emotions was crucial to understanding the origins of man. If culture made the human mind, as Laland argues, then perhaps we should also explore the role of emotions, biases and irrationality in cultural evolution - and not just intelligence.
In later chapters of the book, Laland offers some unsupported hypotheses in an effort to bridge the gap between primate intelligence and human symbolic expression. In his otherwise friendly review of the book, cultural evolutionary scholar Joe Henrich worries that Laland overplays the role of teaching and language in the co-evolution of culture. Laland argues that teaching is the only explanation that can account for not only the increasing fidelity of cultural transmission in humans but also the (somewhat self-imposed) requirement that proto-languages evolved transmit information faithfully and without deception. We'd have to do the modelling to find out which account is more plausible, but given the robust evidence from behavioural economics that deception and public self-justification plays a crucial role in social games the 'social brain' hypothesis remains for me the persuasive position.
What really disappointed me about these later chapters is Laland's seeming lack of engagement with the paleoanthropological record: he never specifies where in the human family tree he thinks these capabilities first evolved; he doesn't engage with the robust debate on the physiological limitations on the language capabilities of our near-relatives; nor with the fact that symbolic culture and exponential cultural progress has only really been a feature of our species on the timescale of tens of thousands of years or so. Teaching, language, rationality and the arts are all highly important to modern human societies, but an account of how these capabilities evolved needs to bootstrap them on to other functions that plausibly existed in earlier members of our lineage that definitively lacked them.
Enter the debate
"Darwin's Unfinished Symphony: How Culture Made the Human Mind" is exactly the sort of book we should embrace as part of a second wave of pop science explainers of gene-culture evolution. Laland takes the extended evolutionary synthesis and cultural evolution as a given, and uses those theories to motivate and explain his own perspectives on debates within the field. Like Darwin himself, Laland may ultimately be proven right on some points and wrong on others: what's important is that readers are exposed to these issues in ways that normalise the language and perspectives of gene-culture coevolution. Laland's earlier work focused on the phenomenon of niche construction, in which a species influences its environment and thereby changes the selection pressures acting upon it. As a social species, the social environment is undoubtedly the niche that humans have created for our own evolution - and it's that control over our own environment that frees us from biological determinism like that espoused by Peterson, Dawkins and Pinker. It opens minds to the possibility that we - as a species - are not done with our social evolution just yet.