“In this statistical sense, races are real”

Lots of interesting stuff re-told in “A Troublesome Inheritance” by Nicholas Wade and reviewed by H Allen Orr in the NY Review of Books. 

Response to Malik: Thanks for the comments. We are not experts but there are many big-shots around who do have lot to say on this matter. Again it is a pity that the old BP box is lying at the bottom of the sea where no one can find it.

The important question (for us)- is there any new knowledge? A large part of the “analysis” seems to us to be self-serving back-calculation, look at why Middle East or South Asia is struggling and put up a theory to fit the evidence. And often the evidence cited is not that clear-cut at all.

The other side (the establishment) is also of not much help, the only message we hear is that race related issues must be handled with care. We agree, but this will not stop people from speculating about the truth…so it is perhaps better that we thrash out the ideas in the open market-place (any firm judgement is unlikely to come though).

The second possibility is that the changes in
our genomes were driven by natural selection. According to this
hypothesis, the frequencies of genetic variants can diverge among
populations because some variants increased the fitness of their
carriers, perhaps by increasing their chances of survival in a harsh
environment encountered on the particular continent on which they lived. 

The study of
genomes provides new ways to find evidence of natural selection.

//////
Wade
also thinks that “evolutionary differences between societies on the
various continents may underlie major and otherwise imperfectly
explained turning points in history such as the rise of the West and the
decline of the Islamic world and China.” 

Here, and especially in his
treatment of why the industrial revolution flourished in England, his
book leans heavily on Gregory Clark’s A Farewell to Alms (2007).
Across these historical turning points, the details differ but the story
remains the same: certain peoples were predisposed genetically to
behaviors and thus institutions that paved the way for their success,
whether, say, economic (the West) or intellectual (the Jews). Other
peoples, alas, had other genes.

Wade, now a freelance writer and reporter, is best known for his work as a journalist at The New York Times. He has also written several popular books on biology. The most recent—Before the Dawn (2006) and The Faith Instinct (2009)—focused on evolution in human beings, including the evolution of religion. In A Troublesome Inheritance,
Wade maintains this focus on human evolution, though he turns to a far
more controversial topic, human races. 

His goal, he says, is “to
demystify the genetic basis of race and to ask what recent human
evolution reveals about history and the nature of human societies.” He
concludes not only that human races are real but that they probably
differ genetically in surprising ways.

Wade’s main claim is that
human races likely differ in social behavior for genetic reasons as a
result of recent evolution. These slight differences in behavior may, in
turn, explain why different sorts of social institutions appear among
different peoples:

Institutions are not just sets of
arbitrary rules. Rather, they grow out of instinctual social behaviors,
such as the propensity to trust others, to follow rules and punish those
who don’t, to engage in reciprocity and trade, or to take up arms
against neighboring groups. Because these behaviors vary slightly from
one society to the next as the result of evolutionary pressures, so too
may the institutions that depend on them.

Evolutionary biology might therefore have something to say about why
some peoples live in modern states and others in tribal societies, and
why some nations are wealthy while others remain mired in poverty.

A Troublesome Inheritance
cleaves neatly into two parts. The first is a review of what recent
studies of the genome reveal about our evolution, including the
emergence of racial differences. The second part considers the part that
genetic differences among races may play in behavior and in the social
institutions embraced by various races. These two parts fare very
differently.

As people dispersed about the planet, they
ultimately settled into the five great “continental races”: Africans
(sub-Sahara), East Asians, Caucasians (Europe, the Indian subcontinent,
and the Middle East), Australians, and Native Americans. Some of these
groups are younger than others (America was peopled only in the last
15,000 years), but this division provides, Wade says, a reasonably
realistic portrait of how human genetic diversity is partitioned
geographically. Because of their geographic isolation from one another,
these groups of human beings necessarily evolved mostly independently
over the last tens of thousands of years. During this period of
independent evolution, much of what we think of as characteristically
human arose, including agriculture and settlement in permanent villages.

So
what has study of the human genome over the last decade revealed?
Wade’s chief conclusion here is that human evolution has been “recent,
copious and regional.” The facts are fairly straightforward. The
continental races of human beings differ somewhat from one other at the
level of DNA sequence. As Wade emphasizes, these
differences are “slight and subtle” but they can nonetheless be detected
by geneticists who now have access to many genome sequences from around
the planet.

The central fact is that genetic differences among
human beings who derive from different continents are statistical.
Geneticists might find that a variant of a given gene is found in 79
percent of Europeans but in only, say, 58 percent of East Asians. Only
rarely do all Europeans carry a genetic variant that does not appear in
all East Asians. But across our vast genomes, these statistical
differences add up, and geneticists have little difficulty concluding
that one person’s genome looks European and another person’s looks East
Asian. 

To put the conclusion more technically, the genomes of various
human beings fall into several reasonably well-defined clusters when
analyzed statistically, and these clusters generally correspond to
continent of origin. In this statistical sense, races are real.

Natural selection can take a
genetic variant that is beneficial but initially rare and drive it to
much higher frequency in a population. This process leaves a signal in
the genome. Because a whole stretch of DNA that
surrounds the beneficial variant will rise to high frequency along with
the variant, nearly everyone in the population might end up carrying the
same DNA sequence in this part of the genome.
Geneticists will thus see a stretch of the genome that shows unusually
little genetic variation in a population.

Using this or, more
often, related approaches, geneticists have obtained fairly good
evidence of natural selection acting on our genomes. Indeed Wade reports
that 14 percent of the human genome has experienced recent natural
selection. These genomic approaches can’t tell us why natural
selection acted in a particular case (was it, say, adaptation to a new
parasite?), but they can tell us that these bouts of natural selection
were sometimes recent and restricted to particular continents.

Wade’s
survey of human population genomics is lively and generally
serviceable. It is not, however, without error. He exaggerates, for
example, the percentage of the human genome that shows evidence of
recent natural selection. The correct figure from the study he cites is 8
percent, not 14, and even this lower figure is soft and open to some
alternative explanation.
And Wade generally assumes that evidence of selection reflects
adaptation to the ecological environment, whereas some events might
reflect the action of other evolutionary forces like sexual selection,
in which individuals compete for mates, not for survival.

In the latter half of A Troublesome Inheritance, Wade ventures into far more controversial territory. His claims are, in outline, simple enough.

As
human beings evolved over the last tens of thousands of years, the
genetic basis of people’s behavior may have changed, just as the basis
of their skin color did. Some of these changes may have resulted from
Darwinian adaptation to new forms of social life. 

For example, the
“Great Transition” from nomadic life to permanent settlement that began
some 15,000 years ago likely produced a profoundly altered social
environment: populations grew larger, people interacted with more
non-kin, and society became more hierarchical.

In response to this
new environment, social behaviors may have changed by natural
selection. In some societies, people who were less aggressive or more
trusting, for instance, might have prospered under these conditions.
Indeed Wade argues that, because the rich could produce more surviving
children than the poor once permanent settlements appeared, genes for
whatever behaviors underlay their success could spread. “The social
behaviors of the elites could thus trickle down into the rest of
society” by natural selection.

Crucially, Wade says that
“evolution in social behavior has necessarily proceeded independently in
the five major races,” reflecting their geographic and thus genetic
isolation. The net result of all of this, during settlement as well as
other events in recent evolutionary history, is that the continental
races might well come to differ genetically in social behavior.

Why, for instance,
do Chinese immigrants to Malaysia and Thailand succeed so often
compared to the Malays and Thais themselves? After all,

people
are highly imitative, and if Chinese business success were purely
cultural, everyone would find it easy to adopt the same methods. This is
not the case because social behavior, of Chinese and others, is
genetically shaped.

Wade
also thinks that “evolutionary differences between societies on the
various continents may underlie major and otherwise imperfectly
explained turning points in history such as the rise of the West and the
decline of the Islamic world and China.” 

Here, and especially in his
treatment of why the industrial revolution flourished in England, his
book leans heavily on Gregory Clark’s A Farewell to Alms (2007).
Across these historical turning points, the details differ but the story
remains the same: certain peoples were predisposed genetically to
behaviors and thus institutions that paved the way for their success,
whether, say, economic (the West) or intellectual (the Jews). Other
peoples, alas, had other genes.

Readers
should be fully aware that in chapters 6 through 10 they are leaving
the world of hard science and entering into a much more speculative
arena at the interface of history, economics and human evolution.

It perhaps would have been best if this sentence had been reprinted at the top of each page in chapters 6 through 10.
……..

Link: http://www.nybooks.com/articles/archives/2014/jun/05/stretch-genes/
……..

regards