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Category: Human Origins
Take Off Your Inverted Spectrum Glasses: Color’s True Charm is in the Brain
Mark Changizi is an evolutionary neurobiologist and director of human cognition at 2AI Labs. He is the author of The Brain from 25000 Feet, The Vision Revolution, and his newest book, Harnessed: How Language and Music Mimicked Nature and Transformed Ape to Man.
The human fascination with color never ceases to amaze me. Our perceptual experience is filled with shapes and pitches and textures and timbres and depths and on and on, yet color seems to get the lion share of our excitement and philosophical attention. Color seems somehow more artistic than our other perceptual dimensions; it’s simply wonderful to behold, as evinced by the double rainbow guy; and we can’t resist wondering what it would be like to see dimensions of color beyond our own. In fact, RadioLab recently put out a great show on color that nicely conveys the romance we all have toward it.
Question is: Why do we find color so enthralling? One of the reasons may be that the world can seem arbitrarily labeled in color, as if a painter dabbed over everything in order to make it beautiful… and that naturally makes us wonder what a different artist might do. What sort of splendor is a bird—who has an extra dimension of color beyond ours—treated to, for example?
While I, too, feel the wonder of color, I don’t share this above intuition about color and its arbitrariness. It’s an unfortunate intuition, one that seeps its way not only into the minds of laymen, but into our “enhancement” products and even the hallowed halls of philosophy. In trying to explain what’s wrong with the intuition, let me begin with a thought experiment concerning a product that gives the wearer “shape enhancement” vision.
Yes, Ayn, There Is a Social Instinct
Eric Michael Johnson has a master’s degree in evolutionary anthropology focusing on great ape behavioral ecology. He is currently a doctoral student in the history of science at University of British Columbia looking at the interplay between evolutionary biology and politics. He blogs at The Primate Diaries at Scientific American, where this post originally appeared.
“Rand” by Nathaniel Gold
“Every political philosophy has to begin with a theory of human nature,” wrote Harvard evolutionary biologist Richard Lewontin in his book Biology as Ideology. Thomas Hobbes, for example, believed that humans in a “state of nature,” or what today we would call hunter-gatherer societies, lived a life that was “solitary, poor, nasty, brutish and short” in which there existed a “warre of all against all.” This led him to conclude, as many apologists for dictatorship have since, that a stable society required a single leader in order to control the rapacious violence that was inherent to human nature. Building off of this, advocates of state communism, such as Vladimir Lenin or Josef Stalin, believed that each of us was born tabula rasa, with a blank slate, and that human nature could be molded in the interests of those in power.
War Has Deep Roots in Human Nature, But It’s Not Inevitable
Thomas Malthus
In the June 2012 issue of Discover, E. O. Wilson authored a piece with the provocative title, “Is War Inevitable?” Derived from his recent book The Social Conquest of Earth, the narrative has a rather simple answer to the question implied in the title: war is inevitable, because it is part of human nature, and, perhaps more provocatively, it shaped human nature. John Horgan, who recently penned The End of War, rebuts Wilson’s argument in a point-by-point fashion in a companion article, “No, War Is Not Inevitable.” I find myself in a curious position: I agree with John Horgan in terms of the conclusion—that war is not inevitable—but not for the same reasons. While Horgan is right that Wilson relies on a particular, controversial group of ethologists to make the assertion that chimps have frequent inter-group conflicts and humans have always had wars, so Horgan leans upon his own preferred group of scholars to make the opposite points. But both of them, I think, miss the crucial part of the answer: the tricky interplay between nature and nurture.
With a strong background in ecology, Wilson assumes a Malthusian paradigm when it comes to human numbers and human resources. In other words, we are subject to a carrying capacity. When there is a surplus of resources population size increase, and “catches up” to the resource base. After a time an equilibrium develops between population and resources. How? The reality is that for solid evolutionary reasons, individuals do not reduce their own reproductive output altruistically. Rather, the population “self-regulates.” In the jargon there is “intra-species competition,” as individuals and groups scramble for finite resources. (There are also, of course, inter-species factors, like predator, prey, and parasites.) The losers die, while the winners reproduce. Each generation is witness to conflicts which check the population and maintain the equilibrium.
Behind the TIME Cover: Most Human Societies Don’t Get Our Breastfeeding Hang-up
Eric Michael Johnson has a master’s degree in evolutionary anthropology focusing on great ape behavioral ecology. He is currently a doctoral student in the history of science at University of British Columbia looking at the interplay between evolutionary biology and politics. He blogs at The Primate Diaries at Scientific American, where this post originally appeared.
“Attachment (with respect to Martin Schoeller),” by Nathaniel Gold
My son will be 3 years old next month and is still breastfeeding. In other words, he is a typical primate. However, when I tell most people about this the reactions I receive run the gamut from mild confusion to serious discomfort. Their concerns are usually that extended breastfeeding could be stunting his independence and emotional development–the “Linus Blanket Syndrome” in the words of Michael Zollicoffer, a pediatrician at the Herman & Walter Samuelson Children’s Hospital at Sinai Hospital in Baltimore. Worse yet, they hint that it might even cause“destructive” psychosexual problems that he will be burdened with throughout his adult life. Could they be right? Was our choice “a prescription for psychological disaster” as Fox News psychiatrist Keith Ablow wrote in response to TIME magazine’s provocative cover article on attachment parenting? Just when is the natural age to stop breastfeeding?
One thing I’ve learned in my research on human evolution is that people are quick to assume that what they do is “natural” simply because they don’t know of other examples where things are done differently. The primate brain is a pattern recognition machine and is adapted to quickly identify regularities in our environment. But when we are presented with the same pattern over and over again it is easy to fall victim to what is known as confirmation bias, or coming to false conclusions because the evidence we use does not come from a broad enough sample. In order to avoid falling for this bias on the question of extended breastfeeding the best way forward would be to draw from the largest sample possible: the entire primate lineage.
In their classic paper, “Life History Variation in Primates” published in the premier scientific journal Evolution, the British zoologists Paul H. Harvey at Oxford and Tim Clutton-Brock at Cambridge published the most comprehensive data then available on the world’s primates. The variables they measured included everything from litter size and age at weaning to adult female body weight and length of the estrous cycle among 135 primate species (including humans). By analyzing the relationships between these variables, using a statistical approach known as a regression analysis, they identified striking patterns that held across primate taxa.
One especially strong correlation was that adult female body weight was closely tied to their offspring’s weaning age, so much so that knowing the first would allow you to predict the second with a 91% success rate. As a result, as anthropologist Katherine A. Dettwyler has shown in her book Breastfeeding: Biocultural Perspectives (co-edited with Patricia Stuart-Macadam), it can be calculated that a young primate’s weaning age in days is equal to 2.71 times their mother’s body weight in grams to the 0.56 power. This calculation predicts, given the range of female body sizes around the world from the !Kung-San of South Africa to the Arctic Inuit, that humans should have an average weaning age of between 2.8 and 3.7 years old.
Human Races May Have Biological Meaning, But Races Mean Nothing About Humanity
Razib Khan’s degrees are in biochemistry and biology. He has blogged about genetics since 2002 (see his Discover Blog, Gene Expression), previously worked in software development, is an Unz Foundation Junior Fellow and lives in the western US. He loves habaneros.
…At some future period, not very distant as measured by centuries, the civilized races of man will almost certainly exterminate and replace throughout the world the savage races. At the same time the anthropomorphous apes, as Prof. Schaaffhause has remarked, will no doubt be exterminated. The break will then be rendered wider, for it will intervene between man in a more civilized state, as we may hope, than the Caucasian and some ape as low as a baboon, instead of as at present between the negro or Australian and the gorilla.
- The descent of man, and selection in relation to sex, Volume 1 – by Charles Darwin
The above quote is not to vilify Charles Darwin. On the contrary, I believe Darwin was a scientific hero whose work is the foundation of modern biology. Nevertheless, he was a man of his age. Despite the fact that Darwin was a political liberal from a family of liberals, with pristine credentials in progressive social movements of his day, such as the anti-slavery campaigns, it is clear that he had Victorian biases nonetheless; some of the passages in The descent of man clearly come from a fortunately bygone era, when white scholars and adventurers cataloged and surveyed the unexplored corners of our world, and created taxonomies of the “lower races” as if they were just part of the local fauna. The reality is that Charles Darwin’s age was fundamentally one of white supremacy. In the year 1900, one out of three human beings alive was of European extraction. In the four centuries since Christopher Columbus, Europe and its Diaspora had entered into massive demographic expansion—which many Victorians saw as survival of the fittest. Progressives of the late 19th and early 20th century, such as H. G. Wells, foresaw a future where the “higher races” would naturally marginalize those peoples who were lesser participants in civilization. Such was taken as the judgment of nature.
How 100 years do change things. And yet just as Darwin could not help but reflect the presuppositions of his era, so we in our day can not help but channel the zeitgeist. Like Charles Darwin, today’s scholars have concluded that humans are fundamentally an African species. But unlike Darwin they conclude from this that there is a biological, essential unity of humankind, such that talk of “civilized” and “savage” is rendered moot and irrelevant. We do look through the mirror of our ages darkly, seeing startlingly different insights from the same shadows of reality. Whereas racist assumptions and beliefs were supported by interpretations of science of the 19th century, today we attempt to harness science in the opposing direction.
The topic of human variation, and more plainly, race, is fraught. The past century has seen a wild swing from the widespread acceptance of the idea that human races are real, with big, important differences, to the opposite position: that race is fundamentally an illusion, a social construction of the human mind. But both of these arguments are mistaken. The established modern consensus about the equality of people, irrespective of race, is morally and ethically justified. But these beliefs we hold to be true do not derive from the natural science, which doesn’t present a clear moral lesson.
What If Music and Language Are Neither Instinct nor Invention?
Mark Changizi is an evolutionary neurobiologist and director of human cognition at 2AI Labs. He is the author of The Brain from 25000 Feet, The Vision Revolution, and his newest book, Harnessed: How Language and Music Mimicked Nature and Transformed Ape to Man.”
Earlier this week there was a debate on the origins of music at the Atlantic between two well-known psychologists. Geoffrey Miller (author of The Mating Mind) thinks music is an instinct, one due to sexual selection. On the other side is Gary Marcus (author of Guitar Zero), who believes music is a cultural invention. Given my recent book on the issue, Harnessed, many have asked me where I fall on the question, Is music an instinct or an invention?
My answer is that music is neither instinct nor invention—or, from another perspective, music is both—and this debate provides an opportunity to remind ourselves that there is a third option for the origins of music, an option that I have argued may also underlie our writing and language capabilities.
What if music only has the illusion of instinct? Might there be processes that could lead to music that is exquisitely shaped for our brains, even though music wasn’t something we ever evolved by natural seletion to process? Music in this case wouldn’t be merely an invention, one of the countless things we do that we’re not “supposed” to be doing and that we’re not particularly good at—like logic or rock-climbing. Instead, music would fit our brain like a glove, tightly inter-weaved amongst our instincts…but yet not be an instinct itself.
There is such a process that can give the gleamy shine of instinct to capabilities we never evolved to possess. It’s cultural evolution.
Once humans were sufficiently smart and social that cultural evolution could pick up steam, a new blind watchmaker was let loose on the world, one that could muster designs worthy of natural selection, and in a fraction of the time. Cultural selection could shape our artifacts to co-opt our innate capabilities.
Cultural evolution is an old idea, but there has been a resurgence of interest in it thanks to researchers like Stanislas Dehaene and Laurent Cohen, who have studied how writing neuronally recycles parts of our visual object-recognition hardware (see Reading in the Brain). And in my research I have tried to get down to brass tacks on how culture manages to harness our brain hardware.
Eyes in the Sky Look Back in Time
Charles Q. Choi is a science journalist who has also written for Scientific American, The New York Times, Wired, Science, and Nature. In his spare time, he has ventured to all seven continents.
The Fertile Crescent in the Near East was long known as “the cradle of civilization,” and at its heart lies Mesopotamia, home to the earliest known cities, such as Ur. Now satellite images are helping uncover the history of human settlements in this storied area between the Tigris and Euphrates rivers, the latest example of how two very modern technologies—sophisticated computing and images of Earth taken from space—are helping shed light on long-extinct species and the earliest complex human societies.
In a study published this week in PNAS, the fortuitously named Harvard archaeologist Jason Ur worked with Bjoern Menze at MIT to develop a computer algorithm that could detect types of soil known as anthrosols from satellite images. Anthrosols are created by long-term human activity, and are finer, lighter-colored and richer in organic material than surrounding soil. The algorithm was trained on what anthrosols from known sites look like based on the patterns of light they reflect, giving the software the chance to spot anthrosols in as-yet unknown sites.
This map shows Ur and Menze’s analysis of anthrosol probability for part of Mesopotamia.
Armed with this method to detect ancient human habitation from space, researchers analyzed a 23,000-square-kilometer area of northeastern Syria and mapped more than 14,000 sites spanning 8,000 years. To find out more about how the sites were used, Ur and Menze compared the satellite images with data on the elevation and volume of these sites previously gathered by the Space Shuttle. The ancient settlements the scientists analyzed were built atop the remains of their mostly mud-brick predecessors, so measuring the height and volume of sites could give an idea of the long-term attractiveness of each locale. Ur and Menze identified more than 9,500 elevated sites that cover 157 square kilometers and contain 700 million cubic meters of collapsed architecture and other settlement debris, more than 250 times the volume of concrete making up Hoover Dam.
“I could do this on the ground, but it would probably take me the rest of my life to survey an area this size,” Ur said. Indeed, field scientists that normally prospect for sites in an educated-guess, trial-by-error manner are increasingly leveraging satellite imagery to their advantage.
Are We “Meant” to Have Language and Music?
Mark Changizi is an evolutionary neurobiologist and director of human cognition at 2AI Labs. He is the author of The Brain from 25000 Feet, The Vision Revolution, and his newest book, Harnessed: How Language and Music Mimicked Nature and Transformed Ape to Man.”
What do ironing and hang-gliding have in common? Not much really, except that we weren’t designed to do either of them. And that goes for a million other modern-civilization things we regularly do but are not “supposed” to do. We’re fish out of water, living in radically unnatural environments and behaving ridiculously for a great ape. So, if one were interested in figuring out which things are fundamentally part of what it is to be human, then those million crazy things we do these days would not be on the list.
iStockphoto
But what would be on the list?
At the top of the list of things we do that we’re supposed to be doing, and that are at the core of what it is to be human rather than some other sort of animal, are language and music. Language is the pinnacle of usefulness, and was key to our domination of the Earth (and the Moon). And music is arguably the pinnacle of the arts. Language and music are fantastically complex, and we’re brilliantly capable at absorbing them, and from a young age. That’s how we know we’re meant to be doing them, i.e., how we know we evolved brains for engaging in language and music.
But what if this gets language and music all wrong? What if we’re not, in fact, meant to have language and music? What if our endless yapping and music-filled hours each day are deeply unnatural behaviors for our species? (What if the parents in Footloose* were right?!)
I believe that language and music are, indeed, not part of our core—that we never evolved by natural selection to engage in them. The reason we have such a head for language and music is not that we evolved for them, but, rather, that language and music evolved—culturally evolved over millennia—for us. Our brains aren’t shaped for these pinnacles of humankind. Rather, these pinnacles of humankind are shaped to be good for our brains.
Why Calorie Counts Are Wrong: Cooked Food Provides a Lot More Energy
by Richard Wrangham, as told to Discover’s Veronique Greenwood. Wrangham is the chair of biological anthropology at Harvard University, where he studies the cultural similarities between humans and chimpanzees—including our unique tendencies to form murderous alliances and engage in recreational sexual activity. He is the author of Catching Fire: How Cooking Made Us Human.
When I was studying the feeding behavior of wild chimpanzees in the early 1970s, I tried surviving on chimpanzee foods for a day at a time. I learned that nothing that chimpanzees ate (at Gombe, in Tanzania, at least) was so poisonous that it would make you ill, but nothing was so palatable that one could easily fill one’s stomach. Having eaten nothing but chimpanzee foods all day, I fell upon regular cooked food in the evenings with relief and delight.
About 25 years later, it occurred to me that my experience in Gombe of being unable to thrive on wild foods likely reflected a general problem for humans that was somehow overcome at some point, possibly through the development of cooking. (Various of our ancestors would have eaten more roots and meat than chimpanzees do, but I had plenty of experience of seeing chimpanzees working very hard to chew their way through tough raw meat—and had even myself tried chewing monkeys killed and discarded by chimpanzees.) In 1999, I published a paper [pdf] with colleagues that argued that the advent of cooking would have marked a turning point in how much energy our ancestors were able to reap from food.
To my surprise, some of the peer commentaries were dismissive of the idea that cooked food provides more energy than raw. The amazing fact is that no experiments had been published directly testing the effects of cooking on net energy gained. It was remarkable, given the abiding interest in calories, that there was a pronounced lack of studies of the effects of cooking on energy gain, even though there were thousands of studies on the effects of cooking on vitamin concentration, and a fair number on its effects on the physical properties of food such as tenderness. But more than a decade later, thanks particularly to the work of Rachel Carmody, a grad student in my lab, we now have a series of experiments that provide a solid base of evidence showing that the skeptics were wrong.
Whether we are talking about plants or meat, eating cooked food provides more calories than eating the same food raw. And that means that the calorie counts we’ve grown so used to consulting are routinely wrong. Read More
Bursting the Bubble of Human Intelligence
Mark Changizi is an evolutionary neurobiologist and director of human cognition at 2AI Labs. He is the author of The Brain from 25000 Feet, The Vision Revolution, and his newest book, Harnessed: How Language and Music Mimicked Nature and Transformed Ape to Man.”
I’m king of the world! You are too. We humans—all of us—get props for being the smartest Earthlings. And we’re not merely the smartest. No, we’re the only species worth writing home about; we’re the only truly worth building artificial intelligence to mimic. We’re the smart ones. The rest of the diversity of life may be rich in clever design, like well-engineered tools and gadgets, but they’re not designed to be intelligent. That’s for humans. Rationality and intelligence is something natural selection granted us.
But…what if our Homo sapiens intelligence is radically overrated? What if we’re smarter, but only quantitatively so, not qualitatively? What if many of our Earthly cousins are respectably intelligent after all? More intriguingly, what if there are systematic barriers that lead us to overestimate our true level of intelligence relative to that of others? And, although I won’t get into this here, what are the implications for the rights of chimpanzees, if the chasm between us and them is, instead, a slender fault line? That question has led to a recent movement to ban invasive research on chimpanzees in the U.S., a measure that the EU has already adopted.
Here I’ll discuss just two barriers, a little one and a big one, that conceal how smart we really are—or are not.
Individuality: The Little Bubble
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