Monday, November 27, 2006

Linnaeus Was a Scientist, not an Activist

On November 18, 2006, Nell Boyce filed a story on the origins of the name ‘mammal’ on NPR. She suggested that Linnaeus may have picked the name to promote or encourage breast-feeding and that although “there were other scientists trying to promote alternative terms”, somehow the male-dominated society of Science adopted the Linnaean term not to further the systematic study, organization and naming of life, but instead to keep women at home, to prevent them from working and voting, repressing women of the 18th Century.

It was great radio.  Entertaining and engaging, it was basically correct with respect to Biology.  Theoretically anyway, such a provocative thesis might even be a good thing.  It does challenge us to question the objectivity of Science, as it should. And it clearly illustrates how cultural and social context can bias scientific research. (Read my initial report on that story here).

Although I was tempted to let it go, as time passed it began to bother me.  A response seems justified for several reasons.  First, it wasn’t very good History.  I don’t believe there is sufficient evidence to support the claim and there is plenty of evidence that contradicts it.  But even more importantly, it is fundamentally misleading with respect to the nature of Science.  Although bias is certainly part of Science and any examination of bias in Science should be welcomed, this one left listeners with the mistaken idea that Science is a system of beliefs like any other, that scientific knowledge is just another opinion, just another point of view.  Unfortunately, this story fails to show how Science corrects itself, how it is different from other modes of thinking, and most importantly how successful Linnaeus actually was at getting it right.  Boyce misses an opportunity to demonstrate how he used the newly discovered tools of modern Science to overcome his historical context and see decades—even  centuries—into the future, foreshadowing the most imaginative and innovative discoveries in modern Biology.  And ironically enough, although this story is meant to show gender bias in 17th Century Science, it may actually be a more powerful demonstration of cultural, social and political bias in our own time and the difficulty as well as the importance of understanding the History of Science.

Her argument is essentially based on four points:  First, the observation that only females of the class ‘Mammalia’ breast-feed their young.  Second, there were many other mammalian characteristics shared by both males and females that Linnaeus might have used instead of breast-feeding.  Third, we know he favored breast-feeding over the common practice of hiring a wet-nurse from a pamphlet he published.  And finally, circumstantial evidence that publication of this pamphlet coincided with the first edition of Systema Naturae and contributed to three centuries of male-dominated science while Western women remained trapped in their culturally defined and limited reproductive roles.  Science Historian Londa Schienbinger said, “When Linnaeus connected women to nature and made it seem natural that women—all females—suckle their children, this was the very moment when Western societies decided that women would not be citizens but that they would be compassionate wives, nurturing mothers, in the home.”

Let’s unpack these arguments one at a time to see what we can learn about what Linnaeus actually thought, what he accomplished, the impact of his work and the nature of scientific bias as well as scientific innovation.

First, although it is entertaining to consider alternatives, ‘Mammalia’ is not an unreasonable choice of names for the class at all.  To be sure, there are other mammalian characteristics that Linnaeus might have used instead: hair, for instance.  All mammals have hair and all animals with hair are mammals.  It also turns out that mammals also have distinctive, three part ear bones; characteristic teeth; a single, lower jaw bone; a neo-cortex; a diaphragm; a four-chambered heart; and specialized, high-powered red blood cells.  While both males and females share these features, only hair is readily apparent and easily used in a key to identify members of a class.  So why didn’t Linnaeus derive a Latin name from our hairy hides?

Apart from these anatomical features the most visible of which is hair, mammalian reproduction is perhaps the most dramatic distinguishing feature of the class.  With the exception of the platypus, echidnas or marsupials found only in Australia, mammals give birth to live young.  And although only the females produce milk in mammary glands, all mammalian young are nourished by nursing, both male and female infants alike. Linnaeus certainly realized that, unlike hair, mammary glands are part of a system of reproduction involving many anatomical features and behaviors of both males and females.  With the exception of mice, rats and horses, nipples are highly visible sexual characteristics in both males and females.  Although we have no reason to believe that Linnaeus was any more or less biased than his contemporaries with respect to gender, there is no evidence that he chose to focus on mammary glands because “he was obsessed with breasts,” as Boyce claimed.  An alternative explanation is simpler and more compelling:  that breasts were the most practical, dramatic and visible characteristics of the mammalian reproductive system.

There is also evidence that Linnaeus followed the same guidelines while identifying the many other species, genera or classes in the system of names he invented: there are many identifying characteristics that are only shared by either males or females of the group.  Mode of reproduction, for example, is frequently used even though males and females have distinct roles in the process. For example, although only the female bird actually lays eggs, we say that as a class of animals, birds have feathers, are warm-blooded and lay eggs to reproduce.  Isn’t that like saying mammals as a class suckle their young?

It’s not strange at all that Linnaeus named the class ‘Mammalia.’

Of course, this does not prove that Linnaeus was without bias. Racial stereotyping is one clear example of bias affecting Linnaeus and his contemporaries and is prominent in his naming system. “Within Homo sapiens he proposed four taxa of a lower (unnamed) rank. These categories are, Americanus, Asiaticus, Africanus, and Europeanus. They were based on place of origin at first, and later skin color. Each race had certain characteristics that were endemic to individuals belonging to it. Native Americans were reddish, stubborn, and angered easily. Africans were black, relaxed and negligent. Asians were sallow, avaricious, and easily distracted. Europeans were white, gentle, and inventive.” (Carolus Linnaeus in Wikipedia)

It seems logical to assume that, absent any evidence to the contrary, he probably viewed women based on contemporary models. In her book Nature’s Body:  Gender in the Making of Modern Science, Science Historian Londa Schiebinger shows how otherwise anatomically accurate drawings of women from the period consistently had oversized hips and undersized heads, making a compelling case of gender bias that literally distorted the way that otherwise rational, objective and empirical men perceived their world.  Their anatomy emphasized their role in reproduction but diminished their capacity for intelligent thought and action, along with their potential as contributors to society in general and Science in particular.   Does this prove, however, that Linnaeus used the term ‘mammal’ to repress women?  Hardly.

This is where Boyce and Schiebinger go wrong.  It is one thing to analyze the work of Linnaeus as text and subject it to our own cultural, social and political standards.  It is fine to consider the actual words they wrote, the body of scientific knowledge of the day and compare it to our own. That can be interesting, even revealing.   But it is quite another thing to use such techniques to understand how historical figures actually thought.  And in the History of Science, we should be particularly interested in how they actually thought and what they actually did because —- even more than the body of scientific knowledge —- that is what Science really is.

Moreover, careful historians also try to distinguish between the actions of individuals and their effects on History, some of which may have been unintended.  Consider the “scientific” racial categories and descriptions of Linnaeus, for example.  They were used to defend colonialism, exploitation and slavery for hundreds of years.  We me be able to hold Linnaeus accountable for his thinking but we should not isolate him from his contemporary society in doing so nor can we blame him or even Science as a whole for the consequences of these institutions!  And there is simply no such evidence presented to show that Linnaeus or his contemporaries used the new nomenclature of ‘mammals’ to encourage breast-feeding or to limit the achievements of 18th Century women.

On the contrary, if we look for it, there is ample evidence that Linnaeus struggled mightily to overcome bias, to focus on empirical evidence and to create a objective naming system that included categories and groupings of plants and animals that reveal their true nature and relationships between species.  Linnaeus was a scientist not an activist.

Linnaeus certainly knew the work of Francis Bacon, who lived more than 100 years earlier.  Bertrand Russell wrote in A History of Western Philosophy that Bacon was “the founder of modern inductive method and the pioneer in the attempt at logical systematization of scientific procedure.”  He essentially defined the scientific process of organizing experimental data or observed facts in categories to develop hypothesis and ultimately to discover general laws or theories.  This is exactly what Linnaeus did, organizing 7,700 species of plants and 4,400 species of animals in System Naturae reaching 3,000 pages by the 13th edition:  he let his data suggest names and groups.

Two examples illustrate how his system was anything but arbitrary and far from political.  I was interested to learn that in the first edition of System Naturae, which was only 11 pages long, Linnaeus placed whales in a category with fish.  By the 13th edition, however, they had assumed their current place in the order Cetacea among the mammals. Bacon knew that bias, social convention, vanity and political influence were all traps that empirical thinkers need to identify and avoid.  He called them “idols.” Although we know that whales are mammals, Linnaeus had to overcome conventional thinking and inertia to accurately observe cetacean anatomy and reclassify them.  This is evidence that Linnaeus understood taxonomy as a scientific process “dedicated to exploring the causes of relationships and similarities among organisms. Classifications are theories about the basis of natural order, not dull catalogues compiled only to avoid chaos." Stephen Jay Gould (1990, p.98)

This illustration of inductive reasoning or generalizing laws or theories from observed data in conjunction with the practice of constant review and revision is worth discussing in every piece of science writing because it is precisely how we know what we know about our universe.  On the one hand it is unsettling to think about because we realize that it is hard, even impossible to be certain about anything.  Unlike deductive reasoning which is rigorous and complete, inductive reasoning is inherently fuzzy and incomplete.  On the other hand, when Science discovers facts that don’t fit accepted models, it is committed to adjusting the models or rejecting them entirely to accommodate the new data.  Historical evidence suggests this is what Linnaeus actually did;  he was the first in a long line of Biologists to do so.

We also have evidence that Linnaeus struggled consciously against Bacon’s “idols” when he first described Homo sapiens and put us together with the other great apes (Homonidae) in the Primate order. In a letter to Johann Georg Gmelin dated February 25, 1747, Linnaeus wrote:  “It is not pleasing to me that I must place humans among the primates…. But I desperately seek from you and from the whole world a general difference between men and simians from the principles of Natural History. I certainly know of none. If only someone might tell me one! If I called man a simian or vice versa I would bring together all the theologians against me. Perhaps I ought to, in accordance with the law of the discipline [of Natural History].”

It is inductive reason, a commitment to observation and empirical evidence and the process of constant review and revision that makes Science a system of beliefs and practices unlike any other.  And it seems to me that this was the reason, not politics, that the Linnaean system was adopted and why we call it the Linnaean enterprise today.

Could a man so compelled by evidence to place Homo sapiens with the apes knowingly choose names or classifications to repress Asians, Africans, Native Americans or women?  It seems unlikely.  Although provocative headlines like “Gender Bias Discovered in 18th Century Science” make great copy, an alternative explanation is at least as good and deserves consideration:  that apart from hair, giving birth to live young and suckling them with milk was simply the most practical, dramatic and visible of the characteristics Linnaeus found in the mammals he studied. Although there was certainly bias in 18th Century Biology (as there is undoubtedly today) there was no political motive in naming the class of animals ‘Mammalia’ nor were gender politics involved in the acceptance of the name.  And I seriously doubt the name had any impact whatsoever on the practice of wet-nursing – or even more absurdly – voting in the 18th Century.

I can’t help it, though.  I liked the story.  I loved the tone.  It was amusing, engaging and even informative.  But it surely left the wrong impression about who Linnaeus really was, what he accomplished and how he worked.

This viewpoint, how do we know today and how did Linnaeus know what he knew then, is exactly what is missing from science education, science journalism and popular scientific literature today.  It reminds us that science is a particular way of knowing and it shows us what it is.  Mindful of this message, it is possible to organize the same ideas slightly differently to tell a different story, no less entertaining, no less compelling and much more accurate by calling attention to these concerns and making the relationship between science and society explicit, making the process of science transparent, making the philosophy of science accessible. This struggle, what Linnaeus knew and how he knew it, is what is missing from the story on NPR.  And it is important because an understanding of this process is crucial to understanding what Science is all about and how this process continues today.

The original story on NPR
Wikipedia articles on Linnaeus, Schiebinber, some Philosophy and Bacon and his methods.
Note the discussion on this topic on one Wikipedia 'talk' page.
More stuff on the web (see photos of original letter from Linnaeus to Johann Georg Gmelin from 1747):

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