Monthly Archives: November 2015

The Underappreciated Role of Physical Activity in the Battle Against Obesity—Part 2: Children and the (Bidirectional?) Relationship Between Physical Activity and Adiposity.

by Kenneth W. Krause.

[Notable New Media]

Kenneth W. Krause is a contributing editor and “Science Watch” columnist for the Skeptical Inquirer.  Formerly a contributing editor and books columnist for the Humanist, Kenneth contributes frequently to Skeptic as well.  He can be contracted at krausekc@msn.com.

Exercising Children 3

Is physical activity, including structured exercise, an effective strategy in the battle against overweight and obesity?  In part one of this article, I reviewed evidence suggesting that, despite popular media misinformation, most people who maintain weight loss do so through a combination of diet and physical activity.  Nor is it true, as many have reported, that exercisers completely compensate for energy expenditure through increased sedentary time or energy intake.

The National Academies’ Institute of Medicine recently gathered preeminent experts in several relevant fields to summarize the current science exploring “the impact of physical activity in the prevention and treatment of overweight and obesity” (IOM 2015).  Here, I discuss the panel’s conclusions relating to children specifically.

The two most common study designs used to examine children’s health are the cross-sectional and prospective longitudinal models.  While the former measures the explanatory variable (physical activity, in this case) and the outcome (adiposity) at the same time, the latter measures those variables on multiple occasions.  While neither “proves” cause and effect, the longitudinal design is especially capable of supporting inferences that compliment randomized controlled trials by providing important information about real-world patterns.

Panelist Kathleen Janz, professor of health and human physiology and associate director of the University of Iowa Obesity Research and Education Initiative, focused initially on the Iowa Bone Development Study (IBDS), a sixteen-year longitudinal program with which she has been intimately involved since its inception (Kwon et al. 2013, 2015).  The IBDS was one of the first to use an accelerometer to more accurately measure physical activity.  Janz’s team also used dual-energy X-ray absorptiometry (DXA) to sort body composition into lean, fat, and bone tissues, and to distinguish between visceral and subcutaneous fat.

In the IBDS, Janz and her team followed 500 children from the age of five and, to date, have conducted at least eight clinical exams of each child.  Defining obesity as 32 percent body fat in girls and 25 percent in boys, twelve percent of study participants were obese from the beginning.  Unfortunately, another ten percent had joined them by the age of nineteen.

Exercising Children 1

So which variables were found to be potentially explanatory?  Total sedentary time did not matter, according to Janz.  But television viewing time (a subset of total sedentary time) and moderate-to-vigorous physical activity (MVPA) did.  Janz explained her findings in the context of a typical eleven-year-old study participant.  Averaging every variable other than MVPA, her group discovered a 7.5 difference in adiposity between females with high and low levels of MVPA, and a five percent distinction in males.  Averaging every variable except TV time, they revealed a five percent difference in adiposity between girls who watched a great deal of TV and very little TV, and a 9.3 percent difference in boys.  When averaging all variables except both MVPA and TV, Janz’s team found an 11.8 percent difference in female adiposity and a whopping 21.3 percent difference in males.

In a recent cross-sectional study of more than 6000 children aged nine to eleven residing at twelve different locations across the world, another group of researchers came to a similar conclusion (Katzmarzyk et al. 2015).  The best predictor of reduced obesity, they found, was MVPA, rather than either sedentary time or vigorous-intensity physical activity.  More specifically, 55 minutes of daily MVPA was the most reliable predictor of lower obesity rates.

But might inferred causality run in the opposite direction as well?  In other words, does higher adiposity predict less physical activity?  If so, one would be forced to question the logic underlying the Health at Every Size (HAES) movement, as well as the increasingly popular claim that physical fitness, but not excess adiposity, is the more accurate predictor of superior health outcomes.

Indeed, one accelerometer study showed that, while MVPA at age seven did not predict decreased body fat between the ages of seven and ten, body fat percentage at age seven did in fact predict decreased MVPA between ages seven and ten (Metcalf et al. 2011).  More specifically, a ten percent increase in adiposity at age seven was associated with four fewer minutes per day of MVPA at age ten.  According to Janz, a “bidirectional relationship” between physical activity and adiposity might signal the existence of a “positive feedback loop.”

Summarizing the data from the IBDS, Janz instructed that children who consistently engaged in at least 45 minutes of MVPA every day “were 60 percent less likely to end up obese at the age of nineteen than children whose level of MVPA decreased as they aged.”  This evidence, she concluded, supports the current national guidelines emphasizing at least 60 minutes of MVPA per day and two hours or less of television.

Exercising Children 2

 

References:

IOM (Institute of Medicine). 2015. Physical activity: moving toward obesity solutions: workshop summary. Washington, D.C.: The National Academies Press.

Katzmarzyk, P.T., T.V. Barreira, S.T., S.T. Broyles, et al. 2015. Physical activity, sedentary time, and obesity in an international sample of children. Medicine & Science in Sports & Exercise 47(10):2062-2069.

Kwon, S., K.F. Janz, T.L. Burns, et al. 2011. Effects of adiposity on physical activity in childhood: Iowa Bone Development Study. Medicine & Science in Sports & Exercise 43(3):443-448.

Kwon, S., K.F. Janz, E.M. Letuchy, et al. 2015. Developmental trajectories of physical activity, sport, and television viewing during childhood to young adulthood: Iowa Bone Development Study. JAMA: Pediatrics 169(7):666-672.

Metcalf, B.S., J. Hosking, A.N. Jeffery, et al. 2011. Fatness leads to inactivity, but inactivity does not lead to fatness: a longitudinal study in children (EarlyBird 45). Archives of Disease in Childhood 96(10):942-947.

Advertisements

The Underappreciated Role of Physical Activity in the Battle Against Obesity (Part 1).

by Kenneth W. Krause.

[Notable New Media]

Kenneth W. Krause is a contributing editor and “Science Watch” columnist for the Skeptical Inquirer.  Formerly a contributing editor and books columnist for the Humanist, Kenneth contributes regularly to Skeptic as well.  He may be contacted at krausekc@msn.com.

Could it be that Time magazine’s August 17, 2009 cover story announcing “The Myth About Exercise” misled millions of potential exercisers about the true relationship between physical activity (PA) and weight loss and maintenance?  James Hill, professor of pediatrics and medicine at the University of Colorado Denver, and co-founder of the National Weight Control Registry and the America on the Move initiative, seems to think so.

1101090817_400

In the spring of 2015, the National Academies’ Institute of Medicine convened a two-day workshop titled, “Physical Activity: Moving Toward Obesity Solutions.”  Gathering preeminent experts in several relevant fields, the panel’s expressed purpose was to summarize the current science exploring “the impact of physical activity in the prevention and treatment of overweight and obesity and to highlight innovative strategies” for physical fitness.  Their results were recently published by the National Academy of Sciences (IOM 2015).

We all understand that, in the limited context of weight loss and maintenance, those predisposed to excess adiposity cannot outrun, or out-exercise, a poor diet.  And while it might take three minutes to consume a 560-calorie hamburger, for example, one would have to exercise forty-five to sixty minutes, depending on intensity, among other things, to burn it off.  But does that necessarily mean, as the 2009 Time article implied, that PA is a trivial strategy in the difficult battle against an unhealthy bulge?

Not according to Hill, and not according to the science.  Consider first the issue of “compensation.”  Through many popular sources, including Time, we have been led to believe that those who increase their level of PA tend to compensate by either consuming more calories or increasing sedentary behavior.

But, as Hill reveals, a recent systematic review of 30 studies shows that, in most cases, exercisers did in fact not compensate with reductions in non-exercise PA (Washburn et al. 2014).  Another study demonstrated that people who increased their PA tended not to completely compensate with increased caloric intake (Schubert et al. 2013).  In summary, according to Hill, “the scientific literature indicates that when physical activity is added to a weight loss program, the majority of people do not compensate, at least not completely.”  The “net result” of PA, in other words, is “a negative energy balance.”

Between 1960 and 2010, daily occupational (including housework) energy expenditure decreased by 120 calories per day, and more recent statistics suggest a further and continuing decline.  “That is enough,” Hill argues, “to explain most of obesity.”  Every study conducted on highly palatable, energy-dense diets, he continues, has demonstrated less weight gain when PA is added to improved nutrition—“even among people genetically susceptible to weight gain.”

Physical Activity

Here, Doctor Hill draws our attentions to two important concepts.  First, “metabolic flexibility” determines how efficiently our bodies can switch fuels.  During a relative fasting state, a flexible metabolism can quickly suppress glucose oxidation and enhance fat oxidation, whereas an inflexible metabolism maintains “a blunted preference for fat oxidation” and remains unable to suppress the use of glucose.  During an insulin-stimulated state, by contrast, the flexible person can suppress fat oxidation and increase her use of glucose, while the inflexible person is less capable of suppressing fat use and stimulating glucose oxidation.

Metabolic flexibility, Hill contends, is directly related to PA.  While weight loss alone does not necessarily improve the situation, “[w]hen people stop moving, their metabolism loses its flexibility.”  The resulting inflexibility, he reasons, renders people, including calorie-restricting dieters, “more susceptible to storing rather than burning fat.”

Second, some researchers believe that one can control personal energy balance far more efficiently by crossing a “threshold of PA.”  Above that threshold is the “regulated zone,” and below it is the “unregulated zone.”  In the former zone, we would expect to observe “a total compensation of energy intake with increased physical activity” and no weight change.  In such cases, physical activity is “driving the bus” and “food is just along for the ride.”  In the latter, unregulated zone, however, “as physical activity decreases, food intake actually increases.”  Here, a tight coupling between PA and caloric intake collapses, and food is now “driving the bus.”

Physical activity threshold

Hill suspects that decreasing PA “is the reason why most people today occupy the unregulated zone.”  When people do lose weight, of course, their energy needs decrease.  If a 220-pound person, for example, were to lose ten percent of his body weight, his energy demands would also plummet by roughly 170 to 250 calories per day.  What’s the best solution?  Fill that “energy gap,” Hill prescribes, with an increase in PA—which of course is far more sustainable than a decrease in energy intake.

Based on data from Hill’s National Weight Loss Registry, a paltry eight percent of the population will maintain a reduction in weight achieved by improved diet alone.  Despite popular media manipulation and misinformation, most people who maintain weight loss do so through a combination of physical activity and diet.  It is therefore extremely unlikely, Hill stresses, that any individual case of obesity can be resolved with improved nutrition alone, or that the obesity epidemic can be reversed without increasing PA in the broader population.

 

References:

IOM (Institute of Medicine). 2015. Physical activity: moving toward obesity solutions: workshop summary. Washington, D.C.: The National Academies Press.

Schubert, M.M., B. Dresbow, S. Sabapathy, and M. Leveritt. 2013. Acute exercise and subsequent energy intake: a meta-analysis. Appetite 63:92-104.

Washburn, R.A., K. Lambourne, A.N. Szabo, et al. 2014. Does increased prescribed exercise alter non-exercise physical activity/energy expenditure in healthy adults? A systematic review. Clinical Obesity 4(1):1-20.

Biological Race and the Problem of Human Diversity (Cover Article).

by Kenneth W. Krause.

Kenneth W. Krause is a contributing editor and “Science Watch” columnist for the Skeptical Inquirer.  Formerly a contributing editor and books columnist for the Humanist, Kenneth contributes regularly to Skeptic as well.  He may be contacted at krausekc@msn.com.

Race 1

Some would see any notion of “race” recede unceremoniously into the dustbin of history, taking its ignominious place alongside the likes of phlogiston theory, Ptolemaic geocentricism, or perhaps even the Iron Curtain or Spanish Inquisition.  But race endures, in one form or another, despite its obnoxious, though apparently captivating dossier.

In 1942, anthropologist Ashley Montagu declared biological race “Man’s Most Dangerous Myth,” and, since then, most scientists have consistently agreed (Montagu 1942).  Nevertheless, to most Americans in particular, heritable race seems as obvious as the colors of their neighbors’ skins and the textures of their hair.  So too have a determined minority of researchers always found cause to dissent from the professional consensus.

Here, I recount the latest popular skirmish over the science of race and attempt to reveal a victor, if there be one.  Is biological race indeed a mere myth, as the academic majority has asked us to concede for more than seven decades?  Is it instead a scandalously inconvenient truth—something we all know exists but, for whatever reasons, prefer not to discuss in polite company?  Or is it possible that a far less familiar rendition of biological race could prove not only viable, but both scientifically and socially valuable as well?

Race Revived.

The productive questions pertain to how races came to be and the extent to which racial variation has significant consequences with respect to function in the modern world.—Vincent Sarich and Frank Miele, 2004.

I have no reason to believe that Nicholas Wade, long-time science editor and journalist, is a racist, if “racist” is to mean believing in the inherent superiority of one human race over any other.  In fact, he expressly condemns the idea.  But in the more limited and hopefully sober context of the science of race, Wade is a veritable maverick.  Indeed, his conclusions that biological human races (or subspecies, for these purposes) do exist, and conform generally to ancestral continental regions, appear remarkably more consistent with those of the general public.

In his most recent and certainly controversial book, A Troublesome Inheritance: Genes, Race and Human History, Wade immediately acknowledges that the vast majority of both anthropologists and geneticists deny the existence of biological race (Wade 2014).  Indeed, “race is a recent human invention,” according to the American Anthropological Association (AAA 2008), and a mere “social construct,” per the American Sociological Association (ASA 2003).  First to decode the human genome, Craig Venter was also quick to announce during his White House visit in 2000 that “the concept of race has no genetic or scientific basis.”

But academics especially are resistant to biological race, or the idea that “human evolution is recent, copious, and regional,” Wade contends, because they fear for their careers in left-leaning political atmospheres and because they tend to be “obsessed with intelligence” and paralyzed by the “unlikely” possibility that genetics might one day demonstrate the intellectual superiority of one major race over others.

According to Wade, “social scientists often write as if they believe that culture explains everything and race [indeed, biology] explains nothing, and that all cultures are of equal value.”  But “the emerging truth,” he insists, “is more complicated.”  Although the author sees individuals as fundamentally similar, “their societies differ greatly in their structure, institutions and their achievements.”  Indeed, “contrary to the central belief of multiculturalists, Western culture has achieved far more” than others “because Europeans, probably for reasons of both evolution and history, have been able to create open and innovative societies, starkly different from the default human arrangements of tribalism or autocracy.”

Race 6

Wade admits that much of his argument is speculative and has yet to be confirmed by hard, genetic evidence.  Nevertheless, he argues, “even a small shift in [genetically-based] social behavior can generate a very different kind of society,” perhaps one where trust and cooperation can extend beyond kin or the tribe—thus facilitating trade, for example, or one emphasizing punishment for nonconformity—thus advancing rule-orientation and isolationism, for instance.  “[I]t is reasonable to assume,” the author vies, “that if traits like skin color have evolved in a population, the same may be true of its social behavior.”

But what profound environmental conditions could possibly have selected for more progressive behavioral adaptations in some but not all populations?  As the climate warmed following the Pleistocene Ice Age, Wade reminds, the agricultural revolution erupted around 10,000 years ago among settlements in the Near East and China.  Increased food production led to population explosions, which in turn spurred social stratification, wealth disparities, and more frequent warfare.  “Human social behavior,” Wade says, “had to adapt to a succession of makeovers as settled tribes developed into chiefdoms, chiefdoms into archaic states and states into empires.”

Meanwhile, other societies transformed far less dramatically.  “For lack of good soils, favorable climate, navigable rivers and population pressures,” Wade observes, “Africa south of the Sahara remained largely tribal throughout the historical period, as did Australia, Polynesia and the circumpolar regions.”

Citing economist Gregory Clark, Wade then postulates that, during the period between 1200 and 1800 CE—twenty-four generations and “plenty of time for a significant change in social behavior if the pressure of natural selection were sufficiently intense,”—the English in particular evolved a greater tendency toward “bourgeoisification” and at least four traits—nonviolence, literacy, thrift, and patience—thus enabling them to escape the so-called “Malthusian trap,” in which agrarian societies never quite learn to produce more than their expanding numbers can consume, and, finally, to lead the world into the Industrial Revolution.

In other words, according to this author, modern industrialized societies have emerged only as a result of two evolved sets of behaviors—initially, those that favor broader trust and contribute to the breakdown of tribalism, and, subsequently, those that favor discipline and delayed gratification and lead to increased productivity and wealth.  On the other hand, says Wade, Sub-Saharan Africans, for example, though well-adapted to their unique environmental circumstances, generally never evolved traits necessary to move beyond tribalism.  Only an evolutionary explanation for this disparity, he concludes, can reveal, for instance, why foreign aid to non-modern societies frequently fails and why Western institutions, including democracy and free markets, cannot be readily transferred to (or forced upon) yet pre-industrial cultures.

So how many races have evolved in Wade’s estimation?  Three major races—Caucasian, East Asian, and African—resulted from an early migration out of Africa some 50,000 years ago, followed by a division between European and Asian populations shortly thereafter.  Quoting statistical geneticist, Neil Risch, however, Wade adds Pacific Islanders and Native Americans to the list because “population genetic studies have recapitulated the classical definition of races based on continental ancestry” (Risch 2002).

To those who would object that there can be no biological race when so many thousands of people fail to fit neatly into any discreet racial category, Wade responds, “[T]o say there are no precise boundaries between races is like saying there are no square circles.”  Races, he adds, are merely “way stations” on the evolutionary road toward speciation.  Different variations of a species can arise where different populations face different selective challenges, and humans have no special exemption from this process.  However, the forces of differentiation can reverse course when, as now, races intermingle due to increased migration, travel, and intermarriage.

Race Rejected.

It is only tradition and shortsightedness that leads us to think there are multiple distinct oceans.—Guy P. Harrison, 2010.

So, if we inherit from our parents traits typically associated with race, including skin, hair, and eye color, why do most scientists insist that race is more social construct than biological reality?  Are they suffering from an acute case of political correctness, as Wade suggests, or perhaps a misplaced paternalistic desire to deceive the irresponsible and short-sighted masses for the greater good of humanity?  More ignoble things have happened, of course, even within scientific communities. But according to geneticist Daniel J. Fairbanks, the denial of biological race is all about the evidence.

In his new book, Everyone is African: How Science Explodes the Myth of Race, Fairbanks points out that, although large-scale analyses of human DNA have recently unleashed a deluge of detailed genetic information, such analyses have so far failed to reveal discrete genetic boundaries along traditional lines of racial classification (Fairbanks 2015).  “What they do reveal,” he argues, “are complex and fascinating ancestral backgrounds that mirror known historical immigration, both ancient and modern.”

Fairbanks

In 1972, Harvard geneticist Richard Lewontin analyzed seventeen different genes among seven groups classified by geographic origin.  He famously discovered that subjects within racial groups varied more among themselves than their overall group varied from other groups, and concluded that there exists virtually no genetic or taxonomic significance to racial classifications (Lewontin 1972).  But Lewontin’s word on the subject was by no means the last. Later characterizing his conclusion as “Lewontin’s Fallacy,” for example, Cambridge geneticist A.W.F. Edwards reminded us how easy it is to predict race simply by inspecting people’s genes (Edwards 2003).

So who was right?  Both of them were, according to geneticist Lynn Jorde and anthropologist Stephen Wooding.  Summarizing several large-scale studies on the topic in 2004, they confirmed Lewontin’s finding that about 85-90% of all human genetic variation exists within continental groups, while only 10-15% between them (Jorde and Wooding 2004).  Even so, as Edwards had insisted, they were also able to assign all native European, East Asian, and sub-Saharan African subjects to their continent of origin using DNA alone.  In the end, however, Jorde and Wooding showed that geographically intermediate populations—South Indians, for example—did not fit neatly into commonly conceived racial categories.  “Ancestry,” they concluded, was “a more subtle and complex description” of one’s genetic makeup than “race.”

Fairbanks concurs.  Humans have been highly mobile for thousands of years, he notes.  As a result, our biological variation “is complex, overlapping, and more continuous than discreet.”  When one analyzes DNA from a geographically broad and truly representative sample, the author surmises, “the notion of discrete racial boundaries disappears.”

Nor are the genetic signatures of typically conceived racial traits always consistent between populations native to different geographic regions.  Consider skin color, for example.  We know, of course, that the first Homo sapiens inherited dark skin previously evolved in Africa to protect against sun exposure and folate degradation, which negatively affects fetal development.  Even today, the ancestral variant of the MC1R gene, conferring high skin pigmentation, is carried uniformly among native Africans.

Race 2

But around 30,000 years ago, Fairbanks instructs, long after our species had first ventured out of Africa into the Caucasus region, a new variant appeared.  KITLG evolved in this population prior to the European-Asian split to reduce pigmentation and facilitate vitamin D absorption in regions of diminished sunlight.  Some 15,000 years later, however, another variant, SLC24A5, evolved by selective sweep as one group migrated westward into Europe.  Extremely rare in other native populations, nearly 100% of modern native Europeans carry this variant.  On the other hand, as their assorted skin tones demonstrate, African and Caribbean Americans carry either two copies of an ancestral variant, two copies of the SLC24A5 variant, or one of each.  Asians, by contrast, developed their own pigment-reducing variants—of the OCA2 gene, for example—via convergent evolution, whereby similar phenotypic traits result independently among different populations due to similar environmental pressures.

So how can biology support the traditional, or “folk,” notion of race when the genetic signatures of that notion’s most relied upon trait—that is, skin color—are so diverse among populations sharing the same or similar degree of skin pigmentation?  Fairbanks judges the idea utterly bankrupt “in light of the obvious fact that actual variation for skin color in humans does not fall into discrete classes,” but rather “ranges from intense to little pigmentation in continuously varying gradations.”

To Wade, Fairbanks offers the following reply: “Traditional racial classifications constitute an oversimplified way to represent the distribution of genetic variation among the people of the world. Mutations have been creating new DNA variants throughout human history, and the notion that a small proportion of them define human races fails to recognize the complex nature of their distribution.”

Race 8

A Severe Response.

I use the term scientific racism to refer to scientists who continue to believe that race is a biological reality.—Robert Wald Sussman, 2014.

Since neither author disputes the absence of completely discreet racial categories, one could argue that part of the battle is really one over mere semantics, if not politics. Regardless, critical aspects of Wade’s analysis were quickly and sharply criticized by several well-respected researchers.

Former president of the AAA and co-drafter of its statement on race, Alan Goodman, for example, argues that Wade’s “speculations follow from misunderstandings about most everything, including the idea of race, evolution and gene action, culture and institutions, and most fundamentally, the scientific process” (Goodman 2014). Indeed, he compares Wade’s book to the most maligned texts on race ever published, including Madison Grant’s 1916 The Passing of the Great Race, Arthur Jensen’s 1969 paper proposing racial intelligence differences, and Herrnstein’s and Murray’s 1994 The Bell Curve.

But Wade’s “biggest error,” according to Goodman, “is his inability to separate the data on human variation from race.” He mistakenly assumes, in other words, “that all he sees is due to genes,” and that culture means little to nothing. A “mix of mysticism and sociobiology,” he continues, Wade’s simplistic view of human culture ignores the archeological and historical fact that cultures are “open systems” that constantly change and interact. And although biological human variation can sometimes fall into geographic patterns, Goodman emphasizes, our centuries-long attempt to force all such variation into racial categories has failed miserably.

Characterizing Wade’s analysis similarly as a “spectacular failure of logic,” population geneticist Jennifer Raff takes special issue with the author’s attempt to cluster human genetic variation into five or, really, any given number of races (Raff 2014). To do so, Wade relied in part on a 2002 study featuring a program called Structure, which is used to group people across the globe based on genetic similarities (Rosenberg 2002). And, indeed, when Rosenberg et al. asked Structure to bunch genetic data into five major groups, it produced clusters conforming to the continents.

But, as Raff observes, the program was capable of dividing the data into any number of clusters, up to twenty in this case, depending on the researchers’ pre-specified desire. When asked for six groups, for example, Structure provided an additional “major” cluster, the Kalash of northwestern Pakistan—which Wade arbitrarily, according to Raff, rejected as a racial category. In the end, she concludes, Wade seems to prefer the number five “simply because it matches his pre-conceived notions of what race should be.”

Interestingly, when Rosenberg et al. subsequently expanded their dataset to include additional genetic markers for the same population samples, Structure simply rejected the Kalesh and decided instead that one of Wade’s five human races, the Native Americans, should be split into two clusters (Rosenberg 2005). In any event, Rosenberg et al. expressly warned in their second paper that Structure’s results “should not be taken as evidence of [their] support of any particular concept of ‘biological race.’”

Structure was able to generate discrete clusters from a very limited quantity of genetic variation, adds population geneticist Jeremy Yoder, because its results reflect what his colleagues refer to as isolation-by-distance, or the fact that populations separated by sufficient geographic expanses will display genetic distinctions even if intimately connected through migration and interbreeding (Yoder 2014). In reality, however, human genetic variation is clinal, or gradual in transition between such populations. In simpler terms, people living closer together tend to be more closely related than those living farther apart.

In his review, biological anthropologist Greg Laden admits that human races might have existed in the past and could emerge at some point in the future (Laden 2014). He also concedes that “genes undoubtedly do underlie human behavior in countless ways.” Nevertheless, he argues, Wade’s “fashionable” hypothesis proposing the genetic underpinnings of racially-based behaviors remains groundless. “There is simply not an accepted list of alleles,” Laden reminds, “that account for behavioral variation.”

Chimpanzees, by contrast, can be divided into genetically-based subspecies (or races). Their genetic diversity has proven much greater than ours, and they demonstrate considerable cultural variation as well. Even so, Laden points out, scientists have so far been unable to sort cultural variation among chimps according to their subspecies. So if biologically-based races cannot explain cultural differences among chimpanzees, despite their superior genetic diversity as a species, why would anyone presume the opposite of humans?

Race 7

None of which is to imply that every review of Wade has been entirely negative. Conservative journalist Anthony Daniels (a.k.a. Theodore Dalrymple), for example, praises the author lavishly as a “courageous man … who dares raise his head above the intellectual parapet” (Daniels 2014). While judging Wade’s arguments mostly unconvincing, he nevertheless defends his right to publish them: “That the concept of race has been used to justify the most hideous of crimes should no more inhibit us from examining it dispassionately … than the fact that economic egalitarianism has been used to justify crimes just as hideous …”

Similarly, political scientist and co-author of The Bell Curve, Charles Murray warned readers of the social science “orthodoxy’s” then-impending attempt to “not just refute” Wade’s analysis, “but to discredit it utterly—to make people embarrassed to be seen purchasing it in public” (Murray 2014). “It is unhelpful,” Murray predicts, “for social scientists and the media to continue to proclaim that ‘race is a social construct’” when “the problem facing us down the road is the increasing rate at which the technical literature reports new links between specific genes and specific traits.” Although “we don’t yet know what the genetically significant racial differences will turn out to be,” Murray contends, “we have to expect that they will be many.”

Perhaps; perhaps not. But race is clearly problematic from a biological perspective—at least as Wade and many before him have imagined it. Humans do not sort neatly into separate genetic categories, or into a handful of continentally-based groups. Nor have we discovered sufficient evidence to suggest that human behaviors match to known patterns of genetic diversity. Nonetheless, because no “is” ever implies an “ought,” the cultural past should never define, let alone restrain, the scientific present.

Characterizing Biological Diversity.

Instead of wasting our time “refuting” straw-man positions dredged from a distant past or from fiction, we should deal with the strongest contemporary attempts to rehabilitate race that are scientifically respectable and genetically informed.—Neven Sesardic, 2010.

To this somewhat belated point, I have avoided the task of defining “biological race,” in large measure because no single definition has achieved widespread acceptance. In any event, preeminent evolutionary biologist, Ernst Mayr, once described “geographic race” generally as “an aggregate of phenotypically similar populations of a species inhabiting a geographic subdivision of the range of that species and differing taxonomically from other populations of that species” (Mayr 2002). A “human race,” he added, “consists of the descendants of a once-isolated geographic population primarily adapted for the environmental conditions of their original home country.”

Sounds much like Wade, so far. But unlike Wade, Mayr firmly rejected any typological, essentialist, or folk approach to human race denying profuse variability and mistaking non-biological attributes—especially those implicating personality and behavior—for racial traits. Accepting culture’s profound sway, Mayr warned that it is “generally unwise to assume that every apparent difference … has a biological cause.” Nonetheless, he concluded, recognizing human races “is only recognizing a biological fact”:

Geographic groups of humans, what biologists call races, tend to differ from each other in mean differences and sometimes even in specific single genes. But when it comes to the capacities that are required for the optimal functioning of our society, I am sure that any racial group can be matched by that of some individual in another racial group. This is what population analysis reveals.

So how might one rescue biological race from the present-day miasma of popular imparsimony and professional denialism, perhaps even to the advancement of science and benefit of society? Evolutionary biologist and professor of science philosophy, Massimo Pigliucci, thinks he has an answer.

Race 3

More than a decade ago, he and colleague Jonathan Kaplan proposed that “the best way of making sense of systematic variation within the human species is likely to rely on the ecotypic conception of biological races” (Pigliucci and Kaplan 2003). Ecotypes, they specify, are “functional-ecological entities” genetically adapted to certain environments and distinguished from one another based on “many or a very few genetic differences.” Consistent with clinal variation, ecotypes are not always phylogenetically distinct, and gene flow between them is common. Thus, a single population might consist of many overlapping ecotypes.

All of which is far more descriptive of human evolution than even the otherwise agreeable notion of “ancestry,” for example. For Pigliucci and Kaplan, the question of human biological race turns not on whether there exists significant between-population variation overall, as Lewontin, for example, suggested, but rather on “whether there is [any] variation in genes associated with significant adaptive differences between populations.” As such, if we accept an ecotypic description of race, “much of the evidence used to suggest that there are no biologically significant human races is, in fact, irrelevant.”

On the other hand, as Pigliucci observed more recently, the ecotypic model implies the failure of folk race as well. First, “the same folk ‘race’ may have evolved independently several times,” as explained above in the context of skin color, “and be characterized by different genetic makeups” (Pigliucci 2013). Second, ecotypes are “only superficially different from each other because they are usually selected for only a relatively small number of traits that are advantageous in certain environments.” In other words, the popular notion of the “black race,” for example, centers on a scientifically incoherent unit—one “defined by a mishmash of small and superficial set of biological traits … and a convoluted cultural history” (Pigliucci 2014).

So, while the essentialist and folk concepts of human race can claim “no support in biology,” Pigliucci concludes, scientists “should not fall into the trap of claiming that there is no systematic variation within human populations of interest to biology.” Consider, for a moment, the context of competitive sports. While the common notion that blacks are better runners than whites is demonstrably false, some evidence does suggest that certain West Africans have a genetic edge as sprinters, and that certain East and North Africans possess an innate advantage as long-distance runners (Harrison 2010). As the ecotypic perspective predicts, the most meaningful biological human races are likely far smaller and more numerous than their baseless essentialist and folk counterparts (Pigliucci and Kaplan 2003).

So, given the concept’s exceptionally sordid history, why not abandon every notion of human race, including the ecotypic version? Indeed, we might be wise to avoid the term “race” altogether, as Pigliucci and Kaplan acknowledge. But if a pattern of genetic variation is scientifically coherent and meaningful, it will likely prove valuable as well. Further study of ecotypes “could yield insights into our recent evolution,” the authors urge, “and perhaps shed increased light onto the history of migrations and gene flow.” By contrast, both the failure to replace the folk concept of race and the continued denial of meaningful patterns of human genetic variation have “hampered research into these areas, a situation from which neither biology nor social policy surely benefit.”

References:

American Anthropological Association. 2008. Race continues to define America. http://new.aaanet.org/pdf/upload/Race-Continues-to-Define-America.pdf (last accessed November 12, 2015).

American Sociological Association. 2003. The importance of collecting data and doing social scientific research in race. http://www.asanet.org/images/press/docs/pdf/asa_race_statement.pdf (last accessed November 12, 2015).

Clark, E. 2007. A farewell to alms: a brief economic history of the world. Princeton, NJ: Princeton University Press.

Daniels, A. 2014. Genetic disorder. http://www.newcriterion.com/articleprint.cfm/Genetic-disorder-7903 (last accessed November 19, 2015).

Edwards, A.W.F. 2003. Human genetic diversity: Lewontin’s fallacy. BioEssays 25(8):798-801.

Fairbanks, D.J. 2015. Everyone is African: how science explodes the myth of race. Amherst, NY: Prometheus Books.

Goodman, A. 2014. A troublesome racial smog. http://www.counterpunch.org/2014/05/23/a-troublesome-racial-smog/print (last accessed November 17, 2015).

Harrison, G.P. 2010. Race and reality: what everyone should know about our biological diversity. Amherst, NY: Prometheus Books.

Jorde, L.B. and S.P. Wooding. 2004. Genetic variation, classification and ‘race.’ Nature Genetics 36(11):528-533.

Laden, G. 2014. A troubling tome. http://www.americanscientist.org/bookshelf/id.16216,content.true,css.print/bookshelf.aspx (last accessed November 16, 2015).

Lewontin, R. 1972. The apportionment of human diversity. Evolutionary Biology 6:397.

Mayr, E. 2002. The biology of race and the concept of equality. Daedalus 131(1):89-94.

Montagu, A. 1942. Man’s most dangerous myth: the fallacy of race. NY: Columbia University Press.

Murray, C. 2014. Book review: ‘A Troublesome Inheritance’ by Nicholas Wade: a scientific revolution is under way—upending one of our reigning orthodoxies. http://www.wsj.com/articles/SB10001424052702303380004579521482247869874 (last accessed November 19, 2015).

Pigliucci, M. 2013. What are we to make of the concept of race? Thoughts of a philosopher-scientist. Studies in History and Philosophy of Biological and Biomedical Sciences. 44:272-277.

Pigliucci, M. 2014. On the biology of race. http://www.scientiasalon.wordpress.com/2014/05/29/on-the-biology-of-race/. (last accessed November 22, 2015).

Pigliucci, M. and J. Kaplan. 2003. On the concept of biological race and its applicability to humans. Philosophy of Science 70:1161-1172.

Raff, J. 2014. Nicholas Wade and race: building a scientific façade. http://www.violentmetaphors.com/2014/05/21/nicholas-wade-and-race-building-a-scientific-facade/ (last accessed November 16, 2015).

Risch, N., E. Burchard, E. Ziv, and H. Tang. 2002. Categorization of humans in biomedical research: genes, race and disease. Genome Biology 3(7):1-12.

Rosenberg, N., J.K. Pritchard, J.L. Weber, et al. 2002. Genetic structure of human populations. Science 298(5602):2381-2385.

Rosenberg, N., M. Saurabh, S. Ramachandran, et al. 2005. Clines, clusters, and the effect of study design on the inference of human population structure. PLOS Genetics 1(6):e70.

Sarich, V. and F. Miele. 2004. Race: the reality of human differences. Boulder, CO: Westview Press.

Sesardic, N. 2010. Race: a social deconstruction of a biological concept. Biological Philosophy 25:143-162.

Sussman, R.W. 2014. The myth of race: the troubling persistence of an unscientific idea. Cambridge, MA: Harvard University Press.

Wade, N. 2014. A troublesome inheritance: genes, race and human history. NY: Penguin Press.

Yoder, J. 2014. How A Troublesome Inheritance gets human genetics wrong. http://www.molecularecologist.com/2014/05/troublesome-inheritance/ (last accessed November 16, 2015).