Stephen Jay Gould’s The Mismeasure of Man is one of the classic works of history of science. Gould, who died in 2002, was, as many probably know, not only an evolutionary biologist and influential popularizer of science, but also a vocal critic of racial theories. The Mismeasure of Man is a full-frontal assault on ideas of race and IQ that helped transform they way that many looked upon these issues. The importance of Gould’s work, as Marek Kohn put it in his book The Race Gallery is that ‘it examined both the historical context of race science, and the data too’.

A key part of Gould’s argument, which brought together the historical context and the data, and seemed to reveal how the one influenced the other, was his discussion of the work of nineteenth century racial scientist Samuel Morton, one of the most important scientific figures of his day. When Morton died in 1851, the New York Tribune said of him that ‘probably no scientific man in America enjoyed a higher reputation among scholars throughout the world than Dr Morton.’ His reputation was built on his home collection of more than a thousand human skulls scoured from every corner of the globe. ‘Nothing like it exists anywhere else’, enthused America’s leading naturalist of the time Louis Agassiz. Friends and enemies alike referred to Morton’s charnel house as the ‘American Golgotha’.

Morton was the leading American polygenist of his age, believing that every race had been separately created, and that each was in reality a distinct species, each a ‘primordial organic form’. ‘From remote ages’, Morton wrote on the opening page of his most famous work, Crania Americana, ‘the inhabitants of every extended locality have been marked by certain physical and moral peculiarities, common among themselves and serving to distinguish them from all other people.’ Cranial capacity demonstrated the capacity for civilisation – the larger the skull, the greater the propensity for civilised life. In Crania Americana, Morton suggested that Caucasians possessed the biggest heads with a mean skull size of 87 cubic inches. Blacks had the smallest heads with an average skull of 78 cubic inches. In between came Native Americans, Malays and Mongolians in ascending order. Morton’s work was part of a wider movement, the so-called American School, that made a scientific case for polygenism and became increasingly influential from the 1840s onwards.

In 1978 Gould published a paper in the journal Science that tore apart Morton’s data, dismissing his methods as ‘a patchwork of fudging and finagling in the clear interest of controlling a priori convictions’. That paper later became a chapter in The Mismeasure of Man. When Gould re-analyzed Morton’s data he came to the conclusion that ‘there are no differences to speak of among Morton’s races’. Gould did not accuse Morton of fraud. He was only able to recalculate the figures because Morton had explained all his procedures and published all his raw data, not something that a conscious fraudster would do. But, Gould suggested, Morton’s social prejudices had led to a series of unconscious biases which ‘directed his tabulations along preestablished lines.’

Gould’s analysis has become a classic account of how prejudice can distort scientific results. Many people (myself included) have made use of that analysis. Except that it now appears that it was Gould, not Morton, who distorted his results, seemingly seeing what he wanted to see through his own political preconceptions. An explosive new paper in the open access journal PLoS Biology, ‘The Mismeasure of Science: Stephen Jay Gould versus Samuel George Morton on Skulls and Bias’, by Jason Lewis et al, claims that ‘most of Gould’s criticisms are poorly supported or falsified.’

Gould had analyzed Morton’s skull-size data, but had never actually examined the crania themselves. The authors of the PLoS paper did just that, locating and remeasuring nearly half of Morton’s skulls. They also checked Gould’s methods. They discovered no consistent bias in Morton’s work but found that Gould had, unwittingly or by design, distorted the evidence.

‘If Gould’s hypothesis that Morton physically mismeasured some skulls due to racial bias were correct’ the authors observe, ‘we would expect the mismeasured crania to be non-randomly distributed by population. Specifically, we would expect Morton’s overestimates to be concentrated on “white” crania, whereas his underestimates would be mostly “non-white” crania.’ Lewis et al did find errors in Morton’s data, but they uncovered no systematic bias. If anything, Morton’s errors helped weaken his racial typology. ‘Morton did not manipulate his samples to influence the average cranial capacities, at least not in a detectable manner’, the authors conclude.

Gould had found ‘no differences to speak of among Morton’s races’ only because he himself had indulged in a little bit of ‘fudging and finagling’. Lewis et al show that Gould had selectively left out certain measurements from Morton’s dataset using what they call ‘arbitrary’ criteria. For instance, Morton had used two methods to measure skull size. One was to fill the skull with seeds, the other with lead shot. Morton himself admitted that the seed method was less accurate, particularly so as many skulls had been measured using this method by a less than fastidious assistant. In his final book on craniometry, Catalogue of Skulls of Man, published in 1849, Morton reanalyzed 670 of his skulls using only the shot method.

Gould reanalyzed Morton’s data for Native American skulls from Catalogue of Skulls of Man. He ignored, however, all the skulls that had not also previously been measured by seed. This manoeuvre, for which there seems to be no particular rationale, added three cubic inches to the mean Native American skull size. Gould also miscalculated the mean Caucasian skull size in Morton’s collection, reducing it from 87 in³ to 85 in³.

‘Of the approximately seven minor errors in Morton’s work identified by Gould’, the PLoS authors observe, ’only two appear to be actual errors, and their overall impact confounds rather than supports Morton’s presumed a priori rankings’. As for ‘the substantive criticisms Gould made of Morton’s work, only two are supported here’:

First, Morton indeed believed in the concept of race and assigned a plethora of different attributes to various groups, often in highly racist fashion. This, however, is readily apparent to anyone reading the opening pages of Morton’s Crania Americana. Second, the summary table of Morton’s final 1849 catalog has multiple errors. However, had Morton not made those errors his results would have more closely matched his presumed a priori bias… Ironically, Gould’s own analysis of Morton is likely the stronger example of a bias influencing results.

Skull size is, of course, irrelevant as a measure of racial identity, intelligence, capacity for civilization or just about anything else meaningful. But that’s not the point. Gould wanted to show that Morton’s racial prejudices had led him, consciously or unconsciously, systematically to bias his ‘objective’ measurements. What happened was that Gould himself was led systematically to bias his interpretation of Morton’s measurement. Whether this was conscious or unconscious, whether it was simply sloppy work on Gould’s part or the result of his own ideological commitments, we may never know.

This is not the first time that Gould’s figures have been challenged. In 1988, the journal Current Anthropology published a paper by John S Michael, in which he presented the results of the recalculation of some of Morton’s data and the remeasurement of some of his skulls. While Morton made some errors, Michael wrote:

Contrary to Gould’s interpretation, I conclude that Morton’s research was conducted with integrity… He was trying to understand racial variation and not, as Gould claims, trying to prove Caucasian racial or intellectual superiority.

Modern day scientific racists, such as Philippe J Rushton, seized upon Michael’s paper as a stick with which to beat Gould and to proclaim the rightness of their own bizarre racial theories. Michael’s paper was, however, heavily criticized for its flawed methodology. Indeed, as the PLoS authors themselves observe in an appendix to their paper, ‘While we come to largely similar conclusions as Michael, his analysis does not support his findings’, adding that ‘Michael’s remeasurements are reported erroneously, lack specifics on individual comparisons, and are missing the key data on the population affinity of potentially mis-measured specimens’ and his ‘defense of Morton against Gould’s claims overlooks the most relevant charges made by Gould.’

Such criticisms cannot be leveled at the PloS authors. Not only does their methodology appear robust, but their views on race are very different to those of critics such as Rushton, and far closer to Gould’s:

In re-evaluating Morton and Gould, we do not dispute that racist views were unfortunately common in 19th-century science or that bias has inappropriately influenced research in some cases. Furthermore, studies have demonstrated that modern human variation is generally continuous, rather than discrete or “racial,” and that most variation in modern humans is within, rather than between, populations. In particular, cranial capacity variation in human populations appears to be largely a function of climate, so, for example, the full range of average capacities is seen in Native American groups, as they historically occupied the full range of latitudes. It is thus with substantial reluctance that we use various racial labels, but it is impossible to discuss Morton and Gould’s work without using the terms they employed.

So what are we to make of all this? It remains to be seen, of course, whether or not Lewis et al’s criticisms hold up. ‘Were Gould still alive’, they observe, ‘we expect he would have mounted a defense of his analysis of Morton.’ Nevertheless, there is no reason to assume that the findings are not robust enough to withstand scrutiny.

Scientific racists will no doubt seize upon this paper, as they did upon Michael’s, as evidence for the biological reality of race. In fact Lewis et al’s exposé of Gould’s methods has little relevance to the wider debate about the meaning of race. Morton’s calculations about skull sizes may have been unbiased but his ideas about racial differences have long since been dismantled. Gould’s arguments about Morton’s data may have been demolished. But no so such demolition can rebuild Morton’s discredited ideas about racial differences.

The real importance of the expose of Gould’s dissembling is the light that it throws not on the issue of race but on the often complex relationship between science and ideology. In one sense Gould has been proved right, though not in the way he would have wanted. His distortion of Morton’s data reveals how strongly held ideological beliefs – in this case not racism but anti-racism – can persuade one to see what one wants to see among the thicket of facts.

In another sense, though, Gould has been shown to be wrong. The fact that ‘Morton’s data ‘are reliable despite his clear bias’, Lewis et al point out, ‘weakens the argument of Gould and others that biased results are endemic in science’:

The power of the scientific approach is that a properly designed and executed methodology can largely shield the outcome from the influence of the investigator’s bias. Science… relies on methods that limit the ability of the investigator’s admittedly inevitable biases to skew the results. Morton’s methods were sound, and our analysis shows that they prevented Morton’s biases from significantly impacting his results. The Morton case, rather than illustrating the ubiquity of bias, instead shows the ability of science to escape the bounds and blinders of cultural contexts.

This is true. It is also, however, too easy and comfortable a conclusion. While Morton may not have finagled these particular measurements, his ideological commitment clearly influenced his scientific outlook down to its very core. His belief in distinct racial types, his acceptance of polygenesis, his promotion of a hierarchy of racial groups, his very belief that skull sizes provided a useful means of distinguishing and ranking races – all came not from objective measurements but from a social attachment to ideas of race and superiority that shaped the way that he viewed and understood the facts of human differences. Morton’s racial science was not simply an unfortunate ‘bias’ upon his empirical research, as Lewis et al suggest. It lay at the very heart of his scientific commitment and shaped how he saw the world scientifically.

Ideological bias is not the ‘norm’ in science as Gould claimed in the subtitle to his original Science paper. But nor is the scientific method in itself sufficient to allow science to ‘escape the bounds and blinders of cultural contexts’ as Lewis et al suggest. While a measurement may be objective, the reasons for such a measurement and the meanings that both scientists and non-scientists read into it emerge not out of the scientific method but out of the social and political culture in which scientific debates are situated, a culture that often uses the authority of science to buttress political, social and moral claims.

Morton might have believed in objective measurements, and his measurements have been (in this case at least) free of bias. But there was nothing objective about his racial science. In the particular social and political context of the mid-nineteenth century, the facts of human differences could be read – and indeed, to many people, it seemed could only be read – in a racial fashion. For nineteenth century scientists, racial science was science. In the late twentieth century, many people were equally committed to reading human differences through an anti-racist framework. Politically, such an anti-racist outlook was welcome. From a scientific point of view, however, the conflation of science and ideology was as problematic as it had been in Morton’s era.

We need more, therefore, than simply an affirmation of faith in the scientific method. We need also constant policing of those borderlands where science meets ideology. We need, too, a commitment to skepticism and a willingness constantly to question, particularly in those areas in which science seems unblinkingly to back the predominant social or cultural views.

In the Morton-Gould affair, the strength of the scientific method was revealed not by Morton’s data, as Lewis et al suggest, but by Lewis et al’s own questioning of Gould’s data. What their paper reveals is that the social embeddedness of science is both a weakness and a strength. Scientists live in particular societies, and are shaped by particular cultures. The questions they ask about the world and the interpretations they place on their data are inevitably formed by cultural attitudes, needs and possibilities. Because scientific practice is socially bound, it is open to ideological corruption. But it is also the social embeddedness of science that provides the means to combat such corruption. The weapons we need to defend scientific objectivity are themselves social practices: an open society, the encouragement of free debate, a skepticism of accepting truth on authority, a willingness to question received wisdom, an acknowledgement of the political independence of scientific research. Ironically, it is precisely because science is a social endeavour that it is able to ‘escape the bounds and blinders of cultural contexts’.