A book few will like but cannot refute

kw: book reviews, nonfiction, sociology, population genetics, racism, cultural evolution

The suffix "-ism" has taken on a connotation of misuse of power, primarily in the words ageism, sexism, and most particularly, racism. We need a new suffix to denote recognition of differences without making a value judgment. The "feminist revolution" went as far as it could on the fable that male-female differences were negligible. To some extent, women were enabled to enter and succeed in formerly male-only or male-dominated trades and professions. There is still a ways to go. However, today I observe greater sex distinctions than were seen 50 years ago. Sexism in the workplace has diminished but not vanished. Perhaps one day it shall. But, may it never be that we lose, vive la différence!

I'll forego discussing ageism and get right to the point of the book on review: Races exist, not just because of skin color, but as seen in skeletal and soft-tissue anatomy and even in social attitudes. The book is A Troublesome Inheritance: Genes, Race and Human History by Nicholas Wade. He is, apparently, not beholden to an academic institution, so he has little to lose by exploring a subject no professional academic dares to touch. He writes, "Social scientists often write as if they believe that culture explains everything and race nothing, and that all cultures are of equal value." (p9)

I have said for many years that I am no racist, but that I am a culturist. I may need to find a new term, because by "culturism" I mean the understanding that some cultures or subcultures are better adapted than others to their social and economic environment. I do not mean that particular cultures are of lower intrinsic value, but I do mean that cultural practices that worked well in one milieu will be detrimental in another. In particular, about half the land area of Earth is dominated by so-called "Western culture", based in technology, entrepreneurship, and high education. Members of a culture that does not highly value education and the rule of law will not thrive in the West, even though they might live quite well in another place.

The social sciences are dominated by the notion that human evolution stopped somewhere between 50,000 and 10,000 years ago. Wade has gathered evidence that, as he puts it, "…human evolution has been recent, copious and regional."

• Recent: Wisdom teeth and lower backs. Articles on the history of wisdom teeth speak in terms of millions of years, but in fact, a jawbone 1,000 years old is more likely to have room for the third molars than most modern jawbones, at least among Europeans. I still have my wisdom teeth, but the proportion of Euro-Americans that need them removed increases with every generation. Further, we are still gradually evolving our ability to get through life without permanent damage to our spines. We are in general more lightly constructed than an ancestor of 5,000 years ago. This is called the "Gracilization" of modern humans. It certainly isn't cultural!
• Copious: Genome studies. Some 12% of our genes show evidence of evolution in the past millennium, and some in the past few generations. By adulthood every one of us carries 50-100 mutations that did not originate with our parents. About a thousandth of our body is gonadal tissue, so every 10-20 generations a random mutation will be passed on to our offspring. Looked at another way, about one in 10-20 children born carries a mutation from a parent, not found in that parent's parents, and about one child in a few hundred inherits mutations that occurred in both parents. This is an important factor in genetic drift, as these new genetic changes spread through a population.
• Regional: Reproductive limitations. In spite of strenuous efforts by anti-racists, interracial marriage is still rare. In my circle of friends and acquaintances, I myself and another friend, both of us Caucasian men, are married to Asian women. Another couple is an African-born married to an African-American of mixed ancestry. Everyone else is married strictly within their own race. A low level of intermarriage means that genetic drift moves in different directions in different populations, simply by chance.

Here is the crux of the matter: Do the genetic variations among human populations, so long isolated from one another and not much blended even in this modern, cosmopolitan generation, affect psychology, specifically mental abilities and attitudes? In the past few decades various studies that showed differences between races in IQ were subject to vilification from everyone except a few supremacist crazies. Standard IQ tests such as Stanford-Binet, and the SAT when normed as an IQ test, are normed to Euro-Americans with the average (mean) defined as 100 and a standard deviation (a factor of variation) as 15. On such IQ tests, the group average for Asians is 105-110, and for Africans and African-Americans it is about 90. This makes me wonder, what if a group of scholars in Kenya and Nigeria and other major African countries produced and normed an aptitude test based on their peoples' practices and ways of living? Would it then be the Euros who would score around 90…or lower? Where would Asians score?

Here is where racial origin has a practical effect. The IQ tests used in the West measure one's ability to handle Western technological concepts and, to a certain extent, social concepts. There is a subculture in America called "poor white trash", which denigrates "extra" education beyond "the three R's". These are the kids that beat up and harass the "teacher's pets" and other "nerdy" kids that get good grades. I have seen no IQ results focused on members of this subculture. I'll predict a group IQ in the 80s, if such a study is ever done. Does that mean I think them genetically inferior? No, they do well in a culture in which I would do badly! If they cared to produce a "TQ" test, how would middle-class Euro-Americans score?

Because of the touchy nature of race in America, half of Wade's book explores history and genetics to pin down an appropriate understanding of race in a genetic context. One study to which he refers, by Gregory Clark, shows homicide rates in England from about 1200 AD to the modern era. A Medieval male was 30 times as likely to be murdered as a Renaissance male, and the homicide rate dropped another factor of 10 between 1800 AD and today. News media in Philadelphia decry an "Epidemic of Homicide", citing about 200 yearly murders in a city of 1.5 million. Imagine if the year were 1800 AD and there were 2,000, or in 1300 AD, if there were 40,000-50,000 murders each year! I did not know of this before, and I find it amazing.

These levels of violence all occurred in settled environments, what we'd call "civilization". In purely tribal societies murderous violence is the norm upon meeting a stranger. Such a meeting may result in an immediate fight to the death, but if the two men speak dialects of a common language, they may first discuss their relatives, to determine if they are related and thus not obligated to kill each other. In tribal cultures that still exist, homicide rates are in the 10% range! It is hard for a young man to grow old enough to raise children.

Wade follows Clark and others to describe four factors that enable Western society with its large cities: trust (leading to nonviolence), literacy, thrift, and patience. He explores to what extent these have a genetic basis. Certain enzymes and hormones they produce can greatly affect trust and the propensity to violence, for example. The trust-demoting and violence-promoting version of the underlying genes are found with greater frequency among violent offenders in prisons, and also among those few members of tribal cultures that have been studied. There is the famous "marshmallow test" that determines the level of self-control young children have: They are promised more marshmallows in 15 minutes if they can let one marshmallow sit untouched in their presence while left alone. Follow-up studies show that the kids who wait for the bigger treat do better in school and in their occupations in later life.

Where would the opposite tendency be a benefit? In a starvation economy such as the one described by Malthus in the early 1800s, that so influenced Charles Darwin as he pondered natural selection. When times are good, small differences in many traits make little difference. But when the grain runs out before the next harvest, very small differences in endurance mean that some will live and some will die, and the tiny differences that allowed survival will be amplified in the next generation(s). In such an environment, characteristic of much of humanity prior to the Industrial Revolution (and still the rule in much of the "developing world"), deferring gratification may kill you. The fact that high levels of deferred gratification are possible indicates a genetic shift in just 200-300 years, at least in the West.

Are genes destiny? The visible differences among the five major races (Caucasian, African, East Asian, Australian, and Native American) are not caused by single genes "for" skin color, for example. Each characteristic is underlain by several to several tens of genes, and a small difference in all of them is needed to make skin a radically different color or shape the skull in a way an anatomist can recognize. Greater or lesser levels of trust also result from multiple genes. So too do at least some of the social attitudes that hold Western democracies together.

The increasing prevalence of foreign adoptions by American couples is setting up a natural experiment. The U.S. spent about a trillion dollars to drive certain tribal groups out of power in Iraq and Afghanistan, and tried to install Western-style democracies. Such nation-building efforts were wasted. Will children born of Iraqi or Afghan parents, adopted and raised in America, understand the institutions of our Republic, and thrive here? A few days ago I met two Kurdish men who now live in America, and run a small limousine service. I wonder how Kurdish-born Americans would do in a company like Sears or DuPont or Chase Bank? These men came here as adults. Would young Kurds brought here as infants and raised here have the same propensity to run a small company rather than work for a boss? Is it possible that they simply cannot understand a non-Tribal economy and polity?

That is the tough point for people to swallow. Our brains are part of our bodies. If our bodies are evolving, so also are our brains, meaning that the way we think is an evolutionary product. Culture cannot go beyond the thoughts that the brain finds possible. By further analogy: I happen to think mathematically. Most people don't. Thus I thrived as a computer programmer, a scarce profession. This is not some fluke: one of my brothers has worked as a programmer for NASA, and another is a mechanical engineer, requiring formidable computer skills. Both our parents had engineering skills. All us boys can think mathematically. Most people can't. The book raises the question, what social thoughts can various people think, or not?

Genes are not destiny, but certain combinations of many genes may open some doors and, if not shut others outright, at least hold them half-closed such that extra effort is required to pass through. Ask all the white guys who have fought Mike Tyson or George Foreman, and a string of other black heavyweight boxers, if there isn't something special about certain kinds of big black guys!

Then we find those perennial super-achievers, the Jews. One person in 500 is Jewish. In the first decade of this Century, one in 3 Nobel Prize winners is Jewish. How can this be? Is the newborn brain truly a blank slate? Other cultural groups have hectoring mothers, and strongly push their kids' education. Tiger Mothers come to mind, but how many Tiger Cubs have Nobel Prizes? There is a clue in the Bible: God demanded universal literacy of the people of Israel. They were to read the Torah to their children daily, and raise the children to read it to their offspring. No other people on earth came close to full literacy prior to about 200 years ago. This had to have affected the genetic makeup of the Jews, particularly in those genes that make literacy easier. As Wade points out, Jewish kids who couldn't make the grade tended to leave for Gentile cultures where their literacy was still advantageous, making them bigger frogs in little ponds. Over millennia, this focused scholarship abilities into the remaining Jewish population.

One can not escape a crucial conclusion: "Rich countries have non-tribal, trust-based economies and favorable institutions [principally that even rulers are subject to law —my note]. Poor countries are those that have not fully escaped from tribalism and labor under extractive institutions that reflect their limited radius of trust." (p 196) The "escape" of the West from tribalism was not foreordained. A fortuitous rise in population coincided with great increases in productivity due to the technological advances of the Industrial Revolution, beginning about 300 years ago. Europe including England already had a long history of settled life, though it was sidelined by feudalism for hundreds of years, yet at the same time this fostered a culture of rule-keeping, which I consider an amalgam of the self-control-mediated traits above (principally patience and trust).

To definitively prove the genetic contribution to such trends would take generations, if indeed such studies are ever undertaken—they would be violently opposed by the liberal establishment. I find it strange that the atheistic, amoral establishment agrees wholeheartedly with most Evangelical Christian leaders who proclaim that human evolution is not going on. They differ only in whether they believe it occurred in the distant past. No matter. The migrations of humanity that began 50-70,000 years ago led to five mutually isolated populations. Prior to the Age of Exploration that began a mere 500 years ago, each developed institutions that bear certain resemblances, but also striking differences. European Caucasians, by the luck of the draw, had the right mental equipment to take advantage of a shift in climate and a series of technical breakthroughs. In spite of centuries of trade between Caucasians and Asians, European technology is readily adopted by Chinese and others in the East, yet they add to it only slightly. Perhaps this is the cause of the intense efforts by the Chinese government to hack into Western computer systems and steal industrial secrets.

Humans continue to evolve, including our brains. Perhaps it will take a really pervasive spate of intermarriage to produce the non-racial species that sociologists fantasize already exists.

The naturalist's dilemma

kw: book reviews, nonfiction, natural history, population genetics

A young scientist's education is primarily an exercise in becoming expert at reductionism. This is a necessity. The skills of keenly observing the minutiae of nature are a necessary foundation for all scientific inquiry. Most youngsters like to take things apart, and a good gift for an inquisitive pre-teen is a mechanical alarm clock, to be taken apart, and reassembled. Getting it back together so it works properly is a satisfying accomplishment.

But reductionism is just the beginning of education. In the natural world, there are few things you can disassemble, then reassemble properly. This goes without saying for living things and living systems (ecologies), but even many inorganic systems simply can't be reproduced by human art, and this will always be so.

As a scientist matures, his or her view must broaden, and the syntheses that result from scientific study must become more comprehensive. It is one thing to study one class of enzymes, or some few species of fishes, or the minerals that compose certain ore bodies. It is quite another to fit the enzymes into a metabolism, the fish into an ecology, or the ore body into the creation of a continental province.

I have always considered naturalists to be the most fortunate scientists. Just to be any good at their trade, they need the gifts of a good mind and a humble attitude. They gain the pleasure of a more comprehensive education than most. Then they are privileged to work in a variety of interesting, if not always pleasant, surroundings. Books I read by naturalists frequently mention the beauties of the environments that they study. Finally, they gather and synthesize the data and information needed to learn what is really going on and how we humans fit into nature; for it is certain that we remain a part of the natural world, for all our efforts to insulate ourselves from it.

John and Mary Theberge are a naturalist couple, scientists whose honeymoon now spans a generation or more. How fortunate to do work you love, with the person you love! They say it takes five to ten years to become an expert in one's field. It takes another ten or twenty to begin to see "the big picture". The Theberges have had thirty years of observing natural systems, and in my view, are accomplished experts in the ecological view of Earth. Their new book The Ptarmigan's Dilemma: An Exploration Into How Life Organizes and Supports Itself presents the best of their work as a series of studies in population dynamics.

The book is a bit bigger than most, and it took me a while to get through. It rewards careful reading. The population of cells that produce a tissue, the tissues that make up the body of a plant or animal, the assemblage of living things that blanket a mountain side or jungle landscape, and domain after domain of such assemblages that become the ecology of a continent, all have to solve the same problem: capture energy so as to carry out the processes of life and avoid extinction or extermination.

In one statement that resonates with me, the authors write, "[P]opulations are either regulated directly by the environment, or indirectly by internal mechanisms that the environment triggers. In either case, population control is necessity for biological order on Earth." Loss of population control leads to cancer in a body, to decimation of a landscape by a weed species, or to the growing environmental disaster we call modern civilization.

We humans like to think we control nature, but are not under nature's control. If our population were merely the nearly seven billion of us, that would be one thing. But worldwide, we tend about 1.4 billion cattle; that is just one "domestic" species. Those cattle outweigh humanity by 30%. Around the world, we also tend sheep, llamas, elephants, emus, salmon and catfish, which probably weigh in at a similar total mass to the cattle.

The authors take a little more moderate view of climate warming than many. They are alarmed by it, but not alarmist about it. It is, as they state, the largest-scale experiment yet to be conducted by the human race. It will certainly lead to many fascinating studies of how populations around the globe respond to a climatic shift. For example, migrating bird species have had several thousand years to get used to the current interglacial warm period. How soon will they adapt to the new climate?

I wonder how many generations it took the Red Knot (a bird that flies from South America to the Arctic, with a stopover along the Mid-Atlantic shore) to adapt to the great shift in biome productivity that occurred 11,000 years ago when the latest ice age switched off in less than a century? Will they have to adapt even more quickly to the northward biome shift we are forcing right now? Will the Horseshoe Crabs, upon whose eggs the Red Knots feed, change the beaches on which they spawn? In a generation or two, we will know, but we cannot predict what will happen, or how.

For most of the history of Earth, the changes have been more gradual. One sea turtle (I think it is the Loggerhead) has had 100 million years to adapt to the widening Atlantic, and now swims half an ocean to lay eggs on a small cluster of mid-Atlantic islands. When that turtle species first evolved, the swim was just a few miles.

In chapter after chapter, recounting the stories of their charges, the authors help us understand the dilemmas all creatures face to send forth their offspring, hostages to an uncertain future. The Ptarmigan of the title lives on the edge of freezing, and the mother birds make constantly shifting choices for their chicks. The chicks are precocious, and must get their own food from birth. But in a cold springtime, they chill quickly, and the mother calls them to brood under her warm feathers. The authors undertook a study to determine just how close the chicks come to freezing, and how close they come to starving as the weather cools. They found there is still a bit of margin in favor of the chicks; the mother birds don't nest so far north that they'd be unable to raise their chicks.

Another point of interest arose when they studied coop-raised Rock Ptarmigans, a control group for their work. Wild Ptarmigans don't have a gall bladder. Autopsy studies of coop-raised birds showed that they did have gall bladders. It is an example of epigenetics, in this case an organ that is potentially there, but is not grown unless the environment demands it. There was a lot more fat in the coop-raised birds' diet than a wild bird gets, so they grew a gall bladder to cope with the different diet. Epigenetics explains a lot of seemingly hidden features that are expressed only when an environmental shift requires their expression. It is a side point to this book's thesis, but is an area of much study as scientists seek to refine our understanding of natural selection.

In one chapter, the authors ask, what about Humans? Are we still subject to nature's laws? We most certainly are. While we have tried to produce a global perpetual motion machine, we will never be able to extract energy that simply isn't there. What is the world's carrying capacity for Homo sapiens? It is likely that we have already exceeded it. Food may not be the crucial factor. I have been predicting for several years that we will soon enter an era of Water Wars.

Liberal democratic political philosophy is based on the principle, the greatest good for the greatest number. Right now, there is great good for a relative few, a growing "middle class" that is at least comfortable, but an even more rapidly growing underclass for whom the term "misery index" is a sad irony. We measure their penury, but do little about it. There is a reason that a few of the "thirdest" of third world countries have life expectancies not much over forty years. Nature cannot be denied. If the numbers of humans continues to increase, the proportion of them that live with little misery will decrease, perhaps to zero. We are the first species with the cleverness to get ourselves into such a dilemma. Will we have the intelligence to get ourselves out? If we don't, nature will do it for us, but at a much greater cost in human suffering.

I cannot end without recalling the many more lyrical portions of the book. The authors have been privileged to work in some very beautiful landscapes, which typically means landscapes with little human imprint. There aren't many left. I pray that the remaining years of humanity's residence on Earth will be marked by increasingly wise use of the resources nature provides, and of the ecological services (such as fresh water and oxygen) that we consume. For a truly livable Earth, we must find a way to achieve a smaller "human footprint", so we can not only live well without ruining all of Earth, but have the opportunity to experience some of the lovely, wild places that have been wisely kept from being "improved" by short-sighted human ambition.

When did human evolution stop?

kw: book reviews, nonfiction, paleoanthropology, archaeology, historical linguistics, primatology, social anthropology, evolutionary psychology, population genetics, human origins, natural selection

The simple answer to this post's title: It hasn't. Among those who accept evolution of the human animal, it is common to think that we've reached some kind of pinnacle, and no evolutionary change has taken place in the last ten or twenty thousand—or perhaps 100,000—years (For those who don't, of course no evolution has ever taken place). The book Before the Dawn: Recovering the Lost History of Our Ancestors by Nicholas Wade presents a synthesis of what is known and strongly inferred in the disciplines related to human origins. The picture is full of surprises.

Item: When did people begin to wear clothing? Fabrics are so rarely retained in "fossil" deposits, we can't begin to guess. Body lice provide the answer (yuck!). Head lice, equivalent to head-and-body lice in apes, live in the hair. Body lice live only in clothing, and move to the skin to feed, but lay eggs in clothing, because there is too little hair on most human bodies to reliably protect the nits. So when did body lice evolve? Genetic dating from modern head and body louse populations provides the surprising answer: about 70,000 years ago. Such dates currently suffer from large uncertainties, so the actual development of the body louse, shortly (a few thousand years) after clothing became common, occurred before 40,000 years ago, and most likely 80,000 or later.

Item: When did proto-humans lose their body hair? Both chimps and bonobos (once called "pygmy chimps") both have fair skin under that black hair. Only the face, hands and feet are dark, because of a permanent tan. Dark skin over the body probably arose as hair was lost, to protect the skin from the sun. "Black" Africans can be sunburned, but it takes a lot more sun exposure compared to lighter-skinned people. When did darker skin over the whole body evolve? Genetic dating again provides an answer, this time from the genes that produce skin pigments: about 1,200,000 years ago.

Strangely, I looked for information on the "first use of fire", but Wade doesn't mention it. A BBC News article of 22 March 2004 states that early African humans, possibly Homo erectus, seem to have had hearths as early as 1.5 million years ago. Another article, dated 29 April 2004, about H. erectus in Israel, has them using fire in sophisticated ways 790,000 years ago. It seems to me that nakedness arose primarily as a result of fire use. Other explanations, such as sexual selection, seem less compelling.

What is interesting, though, is the million or more years that passed between the loss of hair and the development of clothing. Production of textiles must require a change in thinking that didn't occur earlier. The Acheulian "toolkit" was used by at least three species of Homo from 1.7 million years ago until it was supplanted 250,000 years ago by Mousterian (H. Neanderthalensis in Europe) and Middle Paleolithic (H. Ergaster in Africa) technologies. These related technologies show two things: that there was contact between African and European species of Homo; and that one had attained sufficient brain power to greatly improve their use of stone tools, which the other quickly adopted (it takes less wit to copy than to invent). So, apparently, clothing other than cured skins was an invention later yet.

I've known the term "anatomically modern human" (AMH) for decades. I confess that I didn't think about it much. But later, the term "behaviorally modern human" (BMH) gave me pause. Is there a difference? Sure is, by tens of thousands of years. It seems AMH's, which arose in Africa 100,000 years ago, could pass for human today, as long as they didn't do anything. But they didn't live like BMH's, who lived like the hunter-gatherer groups of today, such as certain "primitive" tribes in South America or New Guinea. Evidence of BMH living appears just after 50,000 years ago in Africa, and about 45,000 years ago in Europe.

AMH living was by foraging and minor hunting. Family groups stayed together, in bands of related families that scattered and coalesced on a daily basis, numbering 50 or fewer. Few activities other than food gathering and preparation, procreation, and sleeping, occurred.

BMH living included much more hunting, of larger game, and specialized plant gathering. A great increase in the use of ornaments and artful trinkets arose. The stone toolkit, called Upper Paleolithic, was much more complex, with specific tools for specific uses, and complex tools made of bone, antler, and ivory. Musical instruments, such as bone flutes, are found for the first time in BMH leavings. The people ritualized burial. And they traded among groups, much more than AMH's, to obtain materials and products found far from their home ranges.

Add one item: About 50,000 years ago, BMH's from the "ancestral human population" (AHP) in Africa migrated beyond Africa, apparently for the first time since 1.8 million years ago, and established themselves eastward and northwestward to the limits of the Eurasian continent in a few thousand years. They seem to have supplanted and replaced Neandertals in Europe and "archaic Homo" people in Asia, in less than ten thousand years. During this time, some reached Australia, something the archaics didn't do.

When I saw all these together, I was convinced for the first time that the "multiregional" hypothesis, which requires persistent gene flow among the African, European, and Asian species of Homo, must be wrong. What was it that kept Africans from continuing to migrate to Eurasia, at least successfully, between 1.8 million and 50 thousand years ago? The most likely answer is that the land was occupied by Neandertals and archaics, who either drove out or destroyed invaders. In the same way, the AHP in Africa filled at least the Northeast part of that continent and kept the other species from invading.

Once the AHP developed BMH living, they could make better use of resources, had better weapons, and could stay together in larger groups, compared to the other species, and could successfully invade Eurasia. However, even with these advantages, it wasn't a simple walkover. The number of BMH's who became the ancestors of all non-African people was less than 500, and possibly as few as 150.

OK, so what happened since 50,000 years ago? Are we BMH's who have somehow adapted to settled life? Are today's remaining hunter-gatherer (H/G) groups BMH's? Not really. Although BMH's were anatomically very nearly the same as AMH's, there are differences between today's people, both in Africa and Eurasia, and the people of the African AHP. If you were to take a range of modern people, of all races, of various sizes and ages, and pair them up with AHP folks of similar size and age, you'd find the earlier people had thicker skulls and heavier bones at all ages. They were not as heavily built as Neandertals, but were definitely more like American Football players than like Soccer (European Football) players. The AHP's also stayed in smaller groups than members of modern H/G groups do.

The main reason is inter-group combat. There has been a strong tendency among anthropologists to understate the level of aggressiveness and prevalence of warfare among "innocent savages." An unbiased look at the record reveals that the greatest single danger to humans through all ages was and is other humans. Xenophobia is the natural state of the H/G mind, the BMH mind, and the AMH mind, as it was for all earlier species of Homo.

It is now known that groups of chimps engage in wars of extermination against neighboring groups, and that the leading cause of death among males is "chimpicide". Bonobos, with a female-dominated society, do not engage in such warfare...a good reason for turning over all politics to women!

The greatest single cause of both male and female death in most H/G groups is warfare and killing raids between groups. So, while trade arose at least 50,000 years ago, it probably occurred primarily among groups that couldn't exterminate one another, just as it does today among all the mutually warring tribes in New Guinea and South America, for example. "You aren't my brother or cousin, but unless I judge I can destroy you, I'll call you friend...for a while."

My father's cousin, while a missionary in New Guinea in the 1950s, saw frequent warfare and some cannibalism. Two groups of men might trade one day, and slaughter one another the next. A smaller village might have all its men killed, whereupon all their children would be killed, plus most of the women, and the rest taken as concubines.

Let's look at a few numbers. About a third of adult male chimps die in combat. The number is the same among the Yanomamo, a Brazilian tribe of H/G's. One study showed that a typical tribal society lost, on average, 0.5% of its population yearly to warfare (that's ~1% if the men and a smaller proportion of women; and among men, that's a 26% loss per thirty years). However, averages tend to hide incidents. Most inter-tribe warfare is carried out by small battles and raids a few times per year, or perhaps monthly. Pitched battles are much less frequent, but cause huge carnage: A 30% loss on both sides is typical. Modern societies prior to 1900 AD could produce similar death tolls: At the battle of Gettysburg, the Union side lost 21%, and the Confederates lost 30%.

However, the two World Wars of the 20th Century resulted in losses of less than 10% among the soldiery, and a percent or less of the engaged nations' total citizenry. Stalin's purges of the 1940s and '50s were actually worse than either World War in terms of pure carnage...they were wars of another sort. But in 2002, though a number of wars were in progress around the globe, including America's war in Afghanistan, 0.3% of deaths were due to warfare.

But these latter figures are comparing recent wars among settled societies, with wars among H/G societies, BMH societies...and apes! They are probably not entirely fair. Wade doesn't go into this, but by my own study, I find the following: History is full of war stories, from Troy to Sparta to Carthage and so on. But it seems the total toll of warfare among settled societies is typically about half that among H/G societies.

I wonder what is cause and what is effect? Did settlement and agriculture result in a preference for negotiation? Or did the development of more negotiation-prone people—perhaps first among those who profited most from trading—allow settlement to occur?

I'd say it is a coevolutionary change. Our skeletons reflect the fact that we have less reason to fear being bonked on the head some random night, compared to the AHP, and less need for face-to-face combat. Although today's H/G members live very similarly to the AHP, a Yanomamo or Dani person can be socialized to live in a city. I suspect a person brought in a time machine from 40,000 years ago would be unsocializable, or only partly so.

The brain has changed since that time. So far, two genetic changes that determine brain size, and probably size in specific areas, have been found and genetically dated. One occurred 37,000 years ago, the other 6,000 years ago. The people of 50,000 years ago were, from archaeological evidence, able to live in larger groups than earlier peoples. They were able to extend the idea of "kin" to a larger group than before. But each change to the brain seems to have increased the number of "others" a person could tolerate.

By 15,000 years ago, when settlement began, it seems people could tolerate even greater numbers, and additionally, accept direction from leaders. Both are required for a few hundred people to live in continuous close proximity. It seems strange that these first settlements were not primarily agricultural. They seem instead to have been "places to be" between hunting and collecting expeditions, and trade centers. Specialized skills proliferated; the best hunters got their spear and arrow points from the best stoneworkers, as the best clothing makers got needles and other tools from bone workers...and in turn traded clothing to those less skilled.

The later development of agriculture led to much larger settlements, about the time of the 6,000-year-ago bump in brain size. A larger brain adapts one to the need to remember a larger number of people. It was not much later than this that lactose tolerance evolved among those who kept herds of large mammals. To this day, lactose tolerance or intolerance indicates whether your ancestors were farmers or ranchers.

Now think, today an office worker can step out of an apartment and essentially vanish into a city of millions of strangers, and return safely hours later! Rather extraordinary, wouldn't you say?

What other genetic changes have arisen recently? Malaria resistance among those living in subtropical areas has evolved at least twice since 10,000 years ago (one such change causes sickle-cell disease). Our sense of smell is much reduced compared to just 15,000 years ago, because most of the olfactory gene set has become inactive. Whether this is because of the stench of early cities, of because of less need to smell out game, I forbear to speculate!

The changes to brain and body that occurred prior to 50,000 years ago are found in all humans. Those that arose later are found in larger or smaller numbers depending on where a mutation arose and how strong a benefit it ensured.

This leads us to the most visible differences among human populations, those that correlate best with the continent one's ancestors inhabited: we call them races. While skin color is often considered to be the main indicator of race, it is not really the best. The Caucasians in southern India are darker than some Africans; some Japanese (and I don't mean Ainu, which are very pale) are paler than most Caucasians; many Australians (aboriginals not Austro-Brits) are darker than most Africans or Indians. If you take almost anyone, and paint their skin white (or any solid color of your choice), most people can tell at a glance what continental type they typify, and often the subtype (pygmies and Inuit are quite distinctive, for example).

Regardless how extensive "racial" differences are, it seems they arose no more than 12,000 years ago. They reflect, as do many other indicators, that most people in history seldom moved far from the place they were born. The subtypes within continental groups emphasize this. So, rather than the "not politically correct" attitude toward any mention of racial genetics, it would be better to look upon the diversity of human types as a library of the history of humanity.

One thing is sure: We continue to evolve. We are more gracile than the AHP. Gracility may continue, but it has probably already reached it logical limit among East Asians. Even though Chinese fed a "Western" diet grow taller than their parents, they remain on average much slenderer than Europeans. The continually increasing complexity of modern life will, unless civilization collapses, lead to people with larger brains and more multitasking skills, first behaviorally, and over a few generations, genetically. We won't become the bare brains of science fiction, but we may become smaller, thinner, quicker, and less aggressive in the future. Should Homo sapiens survive another 50,000 years, no doubt our descendants will look back at us as quizzically as we look back at the people in Africa, 50,000 years ago, some of whom managed to escape that continent to colonize the rest of the planet.