Monday, November 07, 2005
Uh oh, the backlash against Bruce Lahn is beginning. At first report of the big news, many "Science for the People" [sic] types, tried to play it cool, like none of it threatened them: Lahn and his research were Good, it was just those awful racists misinterpreting his work. But as the reality sets in of what's to come and what it all means, Lahn will find his "mainstream" defense on the wane (if you think critics denying to the high heavens clear evidence for selection was troubling, just wait until issues like intelligence testing enter the mix, that's when the real obfuscation begins). The "editors" at ScienceWeek blog take issue with John Derbyshire's recent National Review piece on Lahn, but that's not surprising, more interesting is the fact that Derbyshire isn't the point, he's just their brief launching pad for slamming the Lahn team themselves; and I must say it's a real pathetic sight. Foremost they take umbrage at the implication that brain size has anything to do with intelligence - of course as the most encephalized animal we are smart enough to know that such an idea is ridiculous:
. . . [the research group of Bruce T. Lahn] nowhere discuss the important fact that within and across present human populations, studies of brains without pathology show no evidence of correlation of brain size with brain function or cultural "achievement". Certainly, if the authors are working on genes apparently associated with brain size, and the authors are also interested in relating their work to current anthropology, one would expect some discussion of their problem, to wit: If greater human brain size is still undergoing evolutionary selection, how come we have no strong correlations between brain size and important functional attributes of the human nervous system? If the brain is still evolving in size, what are the conceivable selection pressures, given no apparent correlation between non-pathological brain size and function? We're unhappy that the authors were not urged by the referees to make some statements about these questions.
Hmm, these quote-unquote "facts" sound a little a lot like complete lies. Not to mince words, I'm just going to quote at length from Thompson and Grey's 2004 paper (PDF) from Nature Reviews Neuroscience:
Imaging studies of intelligence and brain structure. Correlations between intelligence and total brain volume or grey matter volume have been replicated in magnetic resonance imaging (MRI) studies, to the extent that intelligence is now commonly used as a confounding variable in morphometric studies of disease. [compare with "brains without pathology show no evidence of correlation of brain size with brain function"] MRI-based studies estimate a moderate correlation between brain size and intelligence of 0.40 to 0.51. [compare with "no apparent correlation between non-pathological brain size and function"] One MRI study determined the volume of 13 brain regions, and found that the brain regions intercorrelated substantially - a general factor (the first unrotated principal component in a factor analysis) accounted for 48% of the variance. We found that g was significantly linked to differences in the volume of frontal grey matter, which were determined primarily by genetic factors . . . this analysis underestimated the extent to which grey matter volume in each brain region correlates with g. We reported partial correlations that indicated the association between the volume of each brain region and g, independent of other brain regions. In other words, the volume of frontal grey matter had additional predictive validity for g even after the predictive effect of total brain volume was factored out (as is common in morphometric studies).
I encourage you to read the PDF and note the references. I also encourage you to read two more references. First yet another brain size and intelligence meta-analysis (PDF) was published this year by Michael McDaniel. The correlation between brain size and measured intelligence is again about .4 for adult men and women, and a little bit lower for children. Second, for the functional relationship of this correlation, you should read Gilles Gignac et al's chapter 6 in Scientific Study of General Intelligence.
Bottom line: the editors at ScienceWeek are blaming Bruce Lahn for their own ignorance. Besides lying about what the literature does show, they also have the gall to be outraged that Lahn doesn't similarly rely on their own poor sources from the 1960s:
We're also fascinated by the opening sentence of the first paper: "The most distinct trait of Homo sapiens is the exceptional size and complexity of the brain (1,2). That's good, but the problem is the two references are 46 years old and 32 years old, respectively, and we're trying to imagine why anyone would choose these particular references for a report of such research. If we're to choose old references, why not choose von Bonin? But maybe that would be against the approach of these authors. Consider, for example, the following quotation from von Bonin:
Its hard to emphasize how stupid and ignorant this argument is, so I've thought of a good way to illustrate it. Why did the Lahn team reference Harry Jerison's book, Evolution of the Brain and Intelligence, that ScienceWeek finds so archaic and stupid, and not Gerhardt vo Bonin's? Maybe because Jerison's work was revolutionary and is still wildly relevant to the subject and area of study, while Bonin's is a fossil. In the Preface to 2001's Evolutionary Anatomy of the Primate Cerebral Cortex Dean Falk writes:
Beginning with 1973 publication of his classic monograph, Evolution of the Brain and Intelligence, Harry Jerison's ongoing research has had a profound impact on the questions, methods, and theoretical framework that continues to shape the field of brain evolution. On April 2 1998, researchers from Europe, Africa, and the United States gathered in Salt Lake City at the sixty-seventh annual meeting of the American Association of Physical Anthropologists to take part in a symposium that recognized and celebrated Harry Jerison's intellectual influence on the development of our discipline.
The prologue is written by none other than Stephen Jay Gould, widely celebrated among lay intellectuals for his Mismeasure of Man which lampooned many 19th researchers for seeking a link between brain size and intelligence. Gould describes his early resistance and eventual conversion to Jerison's work after realizing that Jerison truly "delivered the goods" - or, as Gould's title pithily informs us, "Size Matters". 
But the semi-recent Internet tool of Google Scholar gives us an even better way to demonstrate it is the ScienceWeek editors, not Bruce Lahn and company, that are truly out of date. In addition to finding papers, GS also gives us a rough indication of how important (or unimportant) a reference has been, by telling us how many other scholarly works have cited it. Then by clicking on that number we get a list of those references, including their dates, and also how many times those references have been cited - giving us an important glimpse into where the beefs at. For instance typing in 'HJ Jerison Evolution of the brain and intelligence', we see that Jerison's book has 231 citations. Clicking on that we see that many of those citations are also highly cited. All of the ones on the first page are cited at least over 50 times. The citations are also very recent, indicating, contra ScienceWeek, that Jerison's book is still relevant to current research. All of the references on the first page are post 1980, a majority are from mid to late 90s, and the rest are post-2000 (including the Falk volume above) . In contrast, we find that 'G von Bonin The evolution of the human brain' has 1 citation! And that citation has 4 citations which themselves trail off to nowhere.
In other words it's a no-brainer why Lahn's team cited Jerison's book instead of von Bonin's. To steal their condescending rhetoric, I suggest the editors "do more homework". But given their editorial earlier this year that Larry Summers comments might be "possible evidence of brain damage", the possibility of their objectivity and honesty on these issues is, of course, highly in doubt. I expect many more shoddy, deceptive attacks on Bruce Lahn and similar genetic researchers in the coming years.
 Also, at the risk of being obvious, I should point out that referencing a book first published in the 1970s because it pioneered a set of ideas is not the same as saying those ideas ended or stopped developing in the 70s. The Falk book is just one collection proving that Jerison and the field have expanded on those original insights ever since.
Actually, given the transparent reason for their opposition, the ScienceWeek folks should be grateful that the Lahn team didn't instead point to the most recent Jerison summary, which is in the 2002 psychometric volume The Handbook of Intelligence, where Jerison not only states that the distinction between the significance of brain size between species and within species is false, but affirms the existence of human race differences in brain size too. He don't connect them, but the dots they ain'ts hard to connect.