Prehistoric sensibilities?: Earlier evolutionary psychology suggested that changes in the human brain lagged behind changes in our environment, but the field itself has been undergoing some rapid evolution. Image: iStockphoto/lolloj
Just like our animal skin–clad ancestors, we gather food with zeal, lust over the most capable mates, and have an aversion to scammers. And we do still wear plenty of animal skins. But does more separate us from our Stone Age forebears than cartoonists and popular psychologists might have us believe?
At first blush, parsing the modern human in terms of behaviors apparently hardwired into the brain over eons of evolution seems like a tidy, straightforward exercise. And 30 years ago, when the field of evolutionary psychology was gaining steam, some facile parallels between ancient and modern behaviors lodged themselves in the popular conceptions of human evolution. "It's very easy to slip into a very simplistic view of human nature," says Robert Kurzban, an associate professor of psychology at the University of Pennsylvania, citing the classic Flintstones stereotype.
Advances in neuroscience and genetics now suggest that the human brain has changed more rapidly—and in different ways—than was initially thought, according to a new paper published online July 19 in PLoS Biology.
"There's been a lot of recent evolution—far more than anyone envisioned in the 1980s when this idea came to prominence," says Kevin Laland, a professor at the University of Saint Andrew's School of Biology in Scotland and co-author of the new paper. He and his colleagues argue that today's better understanding of the pace of evolution, human adaptability and the way the mind works all suggest that, contrary to cartoon stereotypes, modern humans are not just primitive savages struggling to make psychological sense of an alien contemporary world.
A few decades ago, when researchers were laying the groundwork for the field of evolutionary psychology, the idea that evolution was primarily a gradual, almost geologically paced force "was a tenable view," Laland says. More recent studies, however, have found evidence of speedy evolutionary change in animals—as well as hundreds of changes in the human genome that appeared within tens of thousands, rather than over hundreds of thousands or even millions of years.
"It seems implausible that all of that change has been going on without changing how the brain works," Laland says. And if the brain has been changing over the millennia, along with the climate, culture and other environmental conditions, then there might be far less so-called "adaptive lag" than early evolutionary psychology researchers—and the broader public—had previously assumed.
Laland acknowledges that rapid evolution of the brain is not "inevitable by any stretch of the imagination." But he and his co-authors noted that relatively recent changes from "culturally facilitated changes in diet, to aspects of modern living that inadvertently promoted the spread of diseases" have left their mark on the human genome. And those changes have included "genes expressed in the human brain," they wrote.
Creating creature comforts
The inner sanctum of the suburban shopping mall might bear little resemblance to the African savanna on which our ancestors are thought to have evolved. But Laland notes that it is unlikely humans, imperfect though we might be, would consistently design environments to which we are ill suited.
A traditional, more passive take on evolutionary psychology "fails to recognize that humans are changing their environment," and not at all randomly or haphazardly, Laland says. "We've built environments that are well suited to our biology, so we don't find ourselves massively maladapted for the contemporary world."
As much as pop psychology has drawn from the notion that because of our tribal past on the savannas of Africa, we humans are best suited to live in small clusters spread thinly across vast spaces, an evolutionary view of population numbers refutes that notion. Although many other developments and technologies have come along to help us reproduce almost like rabbits, Laland argues that "if it were the case that humans were adapted to environments in the Pleistocene [epoch ending more than 10,000 years ago] but not the Holocene [modern era, which followed], you would expect human populations would have shrunk when they moved into urban environments."
Instead, the variety of environments in which humans seem to thrive highlights the "extraordinary level of adaptive plasticity afforded by our capacities for learning and culture," Laland and his co-authors noted in their paper.
To decipher these dizzying potentials, Laland and his colleagues advocate first taking a functional, neurological approach, tracking down activity in the brain via MRI scans and genetic studies. Figuring out how the brain does what it does on a more fine-grained scale will help, in turn, guide future research to track just how quickly and in what ways the Homo sapiens brain has changed since we regularly engaged in the cliched behavior of clubbing animals or communicating via grunts.