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Sunday, March 22, 2009

SEED Reviews The 10,000 Year Explosion

The latest issue of SEED praises US President Obama's emphasis on science and offers a list of ideas "for revising the role of science in America." The number one recommendation is "Make Scientific Literacy a National Priority."
What's needed is better ways of fostering critical thinking and imagination not only in the nation's schools but among its citizenry.

Scientific literacy is not just about being able to weigh in on scientific debates of the day by parsing climate change or understanding the difference between a theory and a guess. The ability to empirically test one's ideas about the world and discard beliefs in light of new evidence is fundamental to the ideals of a just and democratic society; it brings people to the table to debate issues reasonably and with minimum rhetoric.
Good advice, although I wish they'd mentioned the importance of skepticism along with critical thinking. Scientifically literate citizens should not blindly accept every new breakthrough that appears in the scientific literature.

We must rely on good science journalism to inform the general public. Good science journalists will analyze and distill the latest scientific information and help put it in context. They will explain things that are controversial, but exciting, and avoid being swept up by the inevitable rhetoric that accompanies every new discovery.

T.J. Kelleher is a senior editor at SEED. In this same issue, Kelleher reviews The 10,000 Year Explosion a book by Gregory Cochran and Henry Harpending. Let's see whether the review is an example of critical thinking.

This is a trade book, not a scientific publication. The main thesis of the book is that humans are evolving rapidly. This thesis is supported by several lines of evidence.
  1. A number of just-so stories from anthropology [see Examples of Accelerated Human Evolution]. Some of them are reasonable, many aren't.
  2. A paper published in Dec. 2007 claiming there are thousands of human genes being selected in various populations (Hawks et al. 2007). To the best of my knowledge this analysis has not been independently replicated in the scientific literature and the technology is not without critics.
  3. A paper by Hawks et al. (2008) claiming that human adaptive evolution has recently accelerated by acquiring genes from Neanderthals.
  4. A claim that within the past 1,000 years the IQ of Ashkanazi Jews has increased relative to the general European population because medieval Ashkanazi Jews engaged in occupations that required high intelligence (Cochran et al. 2006). [See Race and Intelligence, Evolution in the Ashkenazi Jewish Population.]
All this makes for a very interesting book and an idea that's worth serious consideration. It will be interesting to discover, over the next few years, whether there are thousands of genes under positive selection, whether there are only hundreds and the rest are being influenced by random genetic drift, or whether the genetic analysis is subject to artifacts.

Let's see what T.J. Kelleher thinks of all this. Here's the first two paragraphs of the review.
"The 10,000 Year Explosion" would be important even if it were only about population genetics and evolutionary biology, but Gregory Cochran and Henry Harpending, a physicist turned biologist and a biological anthropologist, respectively, at the University of Utah, have written something more. This book is a manifesto for and an example of a new kind of history, a biological history and not just of the prehistoric era. Covering broad ground over human history and prehistory, the authors argue for the singular importance of genes in human history, not just as markers but also as makers.

The first four of the book's seven chapters serve as something of a preamble to the final three. Cochran and Harpending first present the evidence for recent, accelerated human evolution after the invention of agriculture. In its own right that argument is a fairly revolutionary proposition, bit one with clear data, both skeletal and genetic, to back it up: investigations of the human genome undertaken as part of the International Hap Map Project and elsewhere have clearly demonstrated that selection has been ongoing and has accelerated over time. This has been a landmark finding in human biology, and Cochran and Harpending, building on their own work and that of others, including John Hawks of the University of Wisconsin-Madison, convincingly tie the advent of architecture—and the stresses resulting from the new diets. new modes of habitation, new animal neighbors, and new modes of living that agriculture made possible—to this accelerated evolution. It is work destined to launch a thousand careers.[My emphasis-LAM]
Is this an example of critical thinking? Is this the best way to enhance scientific literacy?

Cochran, G., Hardy, J., and Harpending, H. (2006) Natural history of Ashkenazi intelligence. J. Biosoc. Sci. 38:659-93.

Hawks, J., Cochran, G., Harpending, H.C., and Lahn, B.T. (2008) A genetic legacy from archaic Homo. Trends Genet. 24:19-23. Epub 2007 Dec 3. [PubMed] [DOI: 10.1016/j.tig.2007.10.003 ]

Hawks, J., Wang, E.T., Cochran, G.M., Harpending, H.C., and Moyzis, R.K. (2007) Recent acceleration of human adaptive evolution. Proc. Natl. Acad. Sci. (USA) 104:20753-20758. Epub 2007 [PubMed] [DOI:10.1073/pnas.0707650104]


  1. Skepticism is lacking as a value, generally, while unthinking credulity seems the norm. From this layman's point of view, science is not a thing or a collection of human beings; it is (or should be) a rigorous process of discovery of the patterns underlying our existence, and not the reasons for these patterns. I see, in print, too many "scientific"-seeming people use the word or concept "belief" or "believe" in their utterances. Science has become a thing to believe in, even by (especially by?) self-proclaimed atheists. I am glad to see this skeptical blog. End of rant. Thanks for listening.

  2. The other name for "just so stories" is "hypotheses." Science doesn't get far without them although technology can proceed for a while.

    Lewontin and his sort did however give us a real innovation--"just ain't so stories." For example:

    anthropogenic global warming? Just ain't so-you're a liberal

    gene differences among human groups? Just ain't so-you're a racist

    evolution? Just ain't so-you're an atheist

    While just ain't so stories have become an important part of American politics and public policy they really haven't done anything for science in my view.

    A good read is U. Segerstraale, "Defenders of the Truth", Oxford 2001.