Why the history of science should matter to scientists

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Science, in practice, is a series of evolutionary processes informed by assumptions and theories, with promising purposes of discovery and dissemination of knowledge to others. In a case study using taxonomy – the field of classifying organisms – Andrew Hamilton and Quentin D. Wheeler argue that these processes need to be informed by precedents in the history of science, asking “[w]if there is really no doubt about the value of the history of science in the humanities, what use is it for practicing scientists? What difference does it make at the bench level? “

Traditionally, taxonomy has centered on identifying similarities and differences between and among species, examining family trees and identifying groups of similar organisms. For example, insects could be grouped together based on the number of wings (if any), whether their bodies were segmented or not, and if so, how many segments. Using these family trees, taxonomists were able to identify how closely related the species were. These classification systems, however, were based only on physical observation, and thus relationships that might only be “visible” at the genetic level have not been discovered.

In the mid-20th century, the method of phenetics was developed, which used computers and algorithms to determine kinship. A biologist would select specimens from a group they wanted to study, then select the characteristics of the specimens to be measured and analyzed. This data would then be translated into numbers that could be fed into algorithms that would calculate degrees of kinship. The results could then be used to identify a previously unranked specimen or to create a map of potential evolutionary relationships.

Table of the animal kingdom (Regnum Animale) from the first edition of Carolus Linnaeus (1735) from Systema Naturae. via Wikimedia Commons

Phenetics requires a number of steps which present the possibility of unintentional errors. Specimen selections, characteristics chosen, and algorithm (s) used can all influence the results of a phenetic study, without any intention on the part of the investigators involved to obtain particular results.

Historians Hamilton and Wheeler then contrast phenetics with a current method of taxonomic research, bar coding DNA. In this approach, depending on the organism (s), biologists will sequence one or more genes which exhibit little variation between individuals of the same species, but a strong variation between individuals of different species. By analyzing these sequences against known species, the relationship of the unknown individual with others can be established.

Neither DNA barcoding nor phenetics, the authors argue, pay attention to the underlying concepts of species and the histories of populations that led to their differences. “Our concern is that some new molecular methods of doing taxonomy repeat a mistake from the recent past of taxonomy, because they produce results that lack a solid basis in the underlying theory. “

For example, since bar coding examines a small portion of genes (usually a sequence within a gene), it can lead to misclassification and not describe all of the diversity. Historians write “at a time when advances in taxonomy are crucial to understanding and preserving biodiversity”, it is even more important to take into account “Darwin’s view that observations need an appropriate theoretical context. to make sense ”.


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By: Andrew Hamilton and Quentin D. Wheeler

Isis, Vol. 99, n ° 2 (June 2008), pp. 331-340

The University of Chicago Press on behalf of The History of Science Society

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