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.
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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.
Brain changes
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.
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17 Comments
Add CommentThis fact is often looked over, but the moment someone understands how to reproduce & reproduces, it ceases to be natural selection & becomes artificial selection. Artificial is a false term, and conscious selection is far better; anyway, a significant portion of human evolution has been, as it is now, conscious selection... that influences the selection of desirable (for better or worse) traits.
Reply | Report Abuse | Link to thisI think you mean helped "some" humans out of the stone age. The descendants of the stragglers can be seen today, out-breeding and out-warring each other.
Reply | Report Abuse | Link to thisI disagree with the quote, "We've built environments that are well suited to our biology, so we don't find ourselves massively maladapted for the contemporary world."
Reply | Report Abuse | Link to thisWe are EXTREMELY maladapted for our contemporary world. Having regular access to energy-dense foods in the form of simple sugars has led to an explosion of obesity in the developed world, making heart disease the leading cause of death. In addition, our modern built environments are more suited for automobiles than human biology. Massive highways, sprawling subdivisions, parking lots and big-box stores have extended the distances to places where we can satisfy our basic needs (food at the grocery store, entertainment at the megaplex, etc.) beyond the practical range of pedestrians. Our artificial habitats, in the U.S. at least, are dangerous and forbidding to a person in their natural state on foot.
In addition, we seem incapable of handling long-term abstract threats successfully and are too easily distracted by the "rustle in the bushes"-type threats that are in close spatial and temporal proximity. Once the threat becomes clear, it is very easy to get people motivated to stop it, but as long as most people can remove themselves from the problem, keeping it an abstraction, it is very difficult to overcome the resistance to change and the entrenched interests that profit from NOT solving the problem.
@sault, I agree with you to a certain degree. We are currently running into a number of problems that we are poorly adapted to resolve, diet being an obvious one. Still one can't argue facts. We are currently living longer than we have in human history. Sure some of us are dying of diseases resulting from poor diets but even most of them are living longer than our prehistoric ancestors. Despite living in crowded cities our chances of being killed by another human being are lower than ever before. So we obviously aren't that poorly adapted to living in groups greater than a few hundred. I would argue that you and the author are both right. I believe we have crafted a modern world that is more favourable to us than our prehistoric world. But, I also think it is our essential human nature that is preventing us from achieving the ultimate environment that is "perfect" for us. Part of that is because there is no such thing as perfect and our nature contributes to that. For example, it would be great to be able to eat what you want when you want and stay at your optimum weight. Does that mean being able to eat a 16oz steak every day, or does it mean only wanting to eat a 6oz steak every other day? Kind of the difference between having what you want and wanting what you have. I do believe though that as we make machines that help us live in our manufactured world that eventually they will be more evolved to live in it than us since their purpose will be to lift us above it. And we all know what happens when you have a well adapted and a poorly adapted organism competing for resources in the same environment.
Reply | Report Abuse | Link to thisIt seems that stress, and all its symptoms, is a common maladaptive physiological response to our increasingly densely populated urban environments. Not that urbanites are still capable of surviving in a real jungle...
Reply | Report Abuse | Link to thisThis SciAm article seems misleading to me. The paper by Bolhuis, et.al. is about the evolution of the field Evolutionary Psychology rather than the evolution of the human brain.
Reply | Report Abuse | Link to thisThe question is asked, "But does more separate us from our Stone Age forebears than cartoonists and popular psychologists might have us believe?"
There seems to be no new evidence that we have evolved since the Pleistocene or even in the last 100,000 years. They seem to be figuring out that we are more adaptable (better problems solvers?) than was previously thought. This does not mean we evolved, just that we are adaptable. To me there is a difference.
The answer to the question in the article still seems to be: no, more does not separate us from our Stone Age forebears. If we were to take a human infant from 50,000 years ago and raise it today, there likely would be no difference from a 21st century infant. Did the research paper or this SciAm article suggest otherwise?
The human brain appears to be the last frontier of human evolution. It has taken us a long time to realize that cranial capacity was not an index of intelligence, that brains work along molecular biology lines, that the brain has been reorganized repeatedly. Early brains stored visual memory in back. Language changed all that. Verbal memory is stored in different places in the brain because it arrived late and there was no more room in the visual-memory storage bin to collect it for rapid retrieval.
Reply | Report Abuse | Link to thisBiological psychiatry is exploring the world of neurotransmitters (less than 10% are known) and making changes in human behavior in their patients by accelerating or decelerating molecular biological flow of major brain neurotransmitters like serotonin, which activates 18 different neuronal cell-wall channels. At last count. It may eventually go to 50. Calcium channels are dependent on access to calcium in the diet. Poor access, low brain activity.
In short, brain research at the Brain Institutes worldwide is still in diapers. We have yet to understand how astrocytes communicate as they lay down myelin sheathing to broadband neuronal pathways. At any and all ages. And exactly how they activate electrical-potential charges. That is a major problem in brain research today. --If interested, I will discuss this in my blog in greater detail next month, at www.paleoepica.com.
Looking back at the mistakes distorts as if subsequent knowledge was available before the decision was made when that is rarely the case.
Reply | Report Abuse | Link to thisWe aren't perfectly adapted to our environment, and since it is a fluid situation we most likely never will be but our situation hardly deserves and all capital exclamation that we extremely maladapted.
Look back some thousand years are we were the ones with small teeth, weak muscles, slow with mediocre senses. It could be argued that was when we were really maladapted in that environment, but we sprouted these big brains for some reasons being argued as diverse as the excess energy from the adaptation that had us walking up right, to diet and cooking and others.
For as long as we can discover we have been adapting the environment and although there has been bad calls along the way on the average we are getting better at keeping ourselves safe to pass on genes, which is what the FDA and FAA and some of the things that some people seem to think were created for no good reason.
@Al Sundel, "when looking at the biological structure of the brain the big question for me is how much of it is there for information processing and how much is there to compensate for the limits of biology? Put another way, can we engineer a "better" brain than the one nature evolved? Do we need to copy the brain in all of its molecular detail or can we generalize, for example a single threshold algorithm compared to modelling thousands of ion channels? To me, in order to replicate the brain's information processing abilities we don't need to understand how, "astrocytes communicate as they lay down myelin sheathing to broadband neuronal pathways" we just need to know axons respond to a signal. If I'm replicating the axon with a wire I'm not interested in how I would myelinate the wire, I am only interested in the conductive properties of the axon. So I don't really buy the "brain is way too complex" or the "we are only scratching the surface of how the brain works." lines of thought. I see good models of neurons and synapses. I see circuit diagrams of brain regions. I see huge gains year over year on understanding how these systems work together. When one says that the brain is a 100b neurons each with an average of 10k interconnections it sounds daunting. But when you understand that brain regions tend to be made up of the same circuit over and over again the number of actual problems to solve drops considerably.
Reply | Report Abuse | Link to thisRe: "...Laland notes that it is unlikely humans, imperfect though we might be, would consistently design environments to which we are ill suited."
Reply | Report Abuse | Link to thisIf we humans have been consistently designing our environments, where does natural selection and evolutionary adaptability fit within the anthropological scheme?
This is a good thread, thanks to all for their comments. I am not of the school that the brain is simple is we just model functions. I have been involved with three start ups in the area sometimes called AI, speech and visions simulators are available, TTS and ASR come free with each computer sold. But they are not smart, nor do they have anything to do with how the brain works.
Reply | Report Abuse | Link to thisKnowing what the myelin sheath does is important as it is not just an insulator or accelerator just because that is all we have observed.
The mistake some make is saying that the 100 Billion neurons are clumped into functions we can duplicate using electronic analogies, to some of us this is no more than a useful party trick, it shines no light on how we really do these things we are crudely simulating.
Recent studies show the number of neurons is over 100 Trillion, not billion, so the network model based on IT science is useless at that scale and we do need new scientific knowledge to go to the next level of understanding.
Funny how each generation re-invents the wheel. It's an excellent article, but these ideas have all been around for at least forty years. I remember we argued about these same ideas forty years ago at the University of Illinois in a class on the evolution of human social behavior.
Reply | Report Abuse | Link to thisConsider that our type of modern Homo sapiens first appeared sometime between 150,000 and 200,000 years ago, but agriculture and village life didn't start until about 10,000 years ago. It probably was because modern humans were originally a "wild animal." It may have taken about 100,000 years of additional evolution for humans to domesticate themselves to the point where settled village life was possible. At least that was a class discussion we had forty years ago.
Still, glad to see a discussion of the idea. I've always felt that the human brain never did stop evolving. We may have evolved faster in the last 6,000 years or so than ever before in our past.
hungry doggy said, "It may have taken about 100,000 years of additional evolution for humans to domesticate themselves to the point where settled village life was possible."
Reply | Report Abuse | Link to thisOr it may have just been the stable climate of the Holocene. Or maybe somebody simply figured out that permanent settlements were best for making beer.
Where's the beef? Nothing new offered on actual genetic changes or "evolution" in the species or the structure of the brain. Nothing new offered in the observation that the brain allows for the transmission of accumulated knowlege - culture, which allows for rapid adaptation to (and exploitation of) changing circumstances and environments.
Reply | Report Abuse | Link to thisSault - you talk much sense.
Reply | Report Abuse | Link to thisI am disappointed that no reference is made to Cochran and Harpending's book The 10,000 Year Explosion: How Civilization Accelerated Human Evolution, in which they provide evidence for rapid change in the human gene pool. Surely competition between groups of agriculturalists, early city states and then larger groupings, involved incredibly intense selection in the human population. There seems an extraordinary avoidance of the role of intense aggression, that we know occurred in human history, in shaping the human gene pool. The challenges of outwitting, out competing, or keeping peace with your competing groups, placed enormous selection pressures on populations. Besides the increased parastical and bacterial challenges humans faced, once agriculture emerged, the selection pressure of war, was paramount in shaping who we are today.
Reply | Report Abuse | Link to thisFor anyone interested, here's the ebook: http://www.pdf-archive.com/2012/01/23/the-10-000-year-explosion/the-10-000-year-explosion.pdf
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