Nested Hierarchies, the Order of Nature: Carolus Linnaeus (2 of 2)

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Organizing Life into Nested Hierarchies
Carolus Linnaeus joined the quest for classification after having trained as a physician at the University of Uppsala. Botany was part of every medical student’s preparation, since most medicines were derived from plants. After making botanical expeditions through Lapland and central Sweden, Linnaeus became convinced that he could organize all of life into a single artificial system, one that would be his first step towards comprehending God’s design in nature.

Systema Naturae title page
Title page of Linnaeus’ Systema Naturae.

In 1735 he published the first edition of his landmark work, Systema Naturae. In it, he identified every species he knew of according to a standard nomenclature, a genus name followed by a species name. Before Linnaeus, naturalists used unwieldy, irregular names that sowed confusion. But he went further. He classified genera together in groups he called families, which he then placed in larger groups called orders, and then kingdoms, like boxes within boxes.

Humans as Primates
Linnaeus’ classification was important in many ways, not the least of which was how he classified humans. He named humans Homo sapiens, and placed us in the genus Homo. He also placed orangutans and chimpanzees, the two apes known at the time, in the genus Homo. And he placed Homo in a family, which he dubbed Primates. Primates also included two other genera, simians and lemurs. Although Linnaeus believed that humans were special beings in God’s creation, he slotted our species into his system as if it were any other.

Linnaeus organized life with an almost geometrical precision, and was so impressed by his own system that he used it to organize rocks and other non-living matter. Although his classification of minerals may now be long forgotten, within the biological world, at any rate, Linnaeus’ system proved to be useful. It was clear and straightforward, making the challenge of classifying new species far easier than previous systems. It became the standard way to organize life’s diversity.

Biologists still use Linnaeus’ conventions today when they name a new species. But Darwin rendered the ideas behind those conventions obsolete. Darwin recognized that evolution could produce the hierarchy of similarities that so impressed Linnaeus, as old species gave rise to new species. Biologists still place pigs, porcupines, and people in Mammalia, but they do so because all the evidence—comparisons of fossils, anatomy, and genes— confirms that they descend from a common ancestor.

Humans in the Linnaean system
The human species in a modern Linnaean system of classification.
• Systema Naturae image courtesy of Systema Naturae.  

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