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Monday, July 27, 2009

Book of the Week: Cuvier and Classification


This week's book of the week relates yet another milestone in the development of a classification system for life on earth. Cuvier's The Animal Kingdom, Arranged According to its Organization, Serving as a Foundation for the Natural History of Animals, was an attempt to classify the animal kingdom on the basis of comparative anatomy, of which Cuvier's entire classification schema was centered.

Cuvier was heavily influenced by Xavier Bichat, the "father of modern histology and pathology," and adapted the principle expounded by this naturalist that articulated two levels of natural existence: vie animale and vie organique. The first referred to an organism's relationship with the environment, including perception, voluntary movement, and sensibility. The second dealt with the faculties that upheld the "inner existence" of the organism, such as the respiratory system. 


This distinction differed from that purported by Linnaeus, which divided life into animal, vegetable, and mineral. Instead, Cuvier followed a conviction that divided natural objects into living (plant and animal) and non-living (mineral) existences. Cuvier's definition of life, influenced by the above mentioned distinction, was thus the ability to "resist for a certain time, the laws which govern inorganic bodies, and even to act on the environment in a way which is entirely contrary to those laws; we use the terms 'life' and 'vital force' to designate these apparent exceptions to the general laws of nature" ( Lecons d'Anatomie Comparée).

Thus, Cuvier's classification of life hinged on an understanding of the internal relationships among constituent parts of an organism that produced life, which in turn was involved in constant conflict with the laws of chemistry and physics that attempted to break it apart. Using these principles, Cuvier established a taxonomic approach based on comparative anatomy that established correlations between the inner systems that maintained life within an organism. While this approach worked well for the formation of higher-level classification schemes, such as at the order level, it did not translate as well to lower groups where the internal system functions did not differ much from organism to organism. Nevertheless, Cuvier is remembered as an important naturalist who attempted to understand and establish a system on which to build the study of nature and life.

This week's book of the week,
The Animal Kingdom, Arranged According to its Organization, Serving as a Foundation for the Natural History of Animals : And an Introduction to Comparative Anatomy, by Georges Cuvier (1834), volume 3 (plates), was contributed by the Natural History Museum, London.