Classification is an important step in understanding the present diversity and past evolutionary history of life on Earth. All modern classification systems have their roots in the Linnaean classification system. It was developed by Swedish botanist Carolus Linnaeus in the s. He tried to classify all living things that were known at his time. He grouped together organisms that shared obvious physical traits, such as number of legs or shape of leaves.
The Linnaean system of classification consists of a hierarchy of groupings, called taxa singular, taxon. Taxa range from the kingdom to the species see Figure below.
The kingdom is the largest and most inclusive grouping. It consists of organisms that share just a few basic similarities. Examples are the plant and animal kingdoms. The species is the smallest and most exclusive grouping. It consists of organisms that are similar enough to produce fertile offspring together. Closely related species are grouped together in a genus.
This chart shows the taxa of the Linnaean classification system. Each taxon is a subdivision of the taxon below it in the chart. For example, a species is a subdivision of a genus. The classification of humans is given in the chart as an example. Perhaps the single greatest contribution Linnaeus made to science was his method of naming species. This method, called binomial nomenclature , gives each species a unique, two-word Latin name consisting of the genus name and the species name.
An example is Homo sapiens , the two-word Latin name for humans. Why is having two names so important? It is similar to people having a first and a last name. In the same way, having two names uniquely identifies a species.
Linnaeus published his classification system in the s. Since then, many new species have been discovered. The biochemistry of many organisms has also become known. A major change to the Linnaean system was the addition of a new taxon called the domain. A domain is a taxon that is larger and more inclusive than the kingdom. Most biologists agree there are three domains of life on Earth: Bacteria, Archaea , and Eukaryota see Figure below.
Both Bacteria and Archaea consist of single-celled prokaryotes. Eukaryota consists of all eukaryotes, from single-celled protists to humans. According to Uppsala University in Sweden, the famous German poet Goethe wrote of Linnaeus, "With the exception of Shakespeare and Spinoza, I know no one among the no longer living who has influenced me more strongly.
His father was a Lutheran minister and amateur botanist who helped instill a love of nature in his son. Linnaeus was especially fond of plants and flowers and was given his own plot of land to start a small garden.
According to William MacGillivray's book " Lives of Eminent Zoologists " Oliver and Boyd, , Linnaeus "devoted a great part of his earlier years to the cultivation of a corner of the family-garden, which he profusely stocked with wild plants collected in the woods and fields. Linnaeus's parents made sure their young son received an extensive education. His father, Nils, taught him Latin, geography and religion in the hope he would become a clergyman.
Later, his parents employed a personal tutor to continue the boy's education in these subjects. Eventually, Linnaeus continued his schooling at the Vaxjo Gymnasium, a school that was designed to prepare young men for careers in the clergy. But his first love was botany. While ostensibly studying for the clergy, he continued to study botany, reading everything he could find on the subject.
Norton and Company, , "because he was usually off rummaging around in some meadow or marsh collecting plants rather than studying Latin and Greek. Rothman was a physician and botanist who was influential in introducing Linnaeus to the period's botanical literature and taught the young man to classify plants using the taxonomic system of the day.
By this time, Linnaeus's father realized that his son would never join the clergy, so reluctantly allowed him to pursue medicine, a career path suggested to Nils by Rothman and one that required students to be well-versed in botany. At age 21, Linnaeus entered Lund University in Sweden, but the next year he transferred to Uppsala University, the country's oldest and most prestigious center of higher learning.
He studied botany and medicine at the university, according to Beil. His expertise impressed his professors so much that he began to teach classes as an undergraduate, frequently lecturing on botany.
During a break in his studies, he traveled to the far north of Scandinavia, to the region known as Lapland on a six-month long research expedition sponsored by the Uppsala Academy of Sciences. The goal was to collect and record different species of plants, animals and minerals.
He also studied the indigenous Sami people also known as Laplanders who inhabited the region and were nomadic reindeer herders, hunters and fishermen. He kept a journal, Beil said, in which he "recorded everything from the way [the Sami] made their beds from moss to how they made their bread. All Swedish medical students were required to receive their degrees outside Sweden, so Linnaeus finished his studies at the University of Harderwijk in the Netherlands in His doctorate was focused on the causes of malaria , Beil said, a malady he erroneously attributed not to mosquitoes but to regions with clay-rich soils.
He remained in the Netherlands for another three years, enrolling in the University of Leiden to continue his studies. His time in the Netherlands played a major role in his education. He soon returned to Sweden, married, and set up his medical practice.
He also helped found the Royal Swedish Academy of Science. He did not remain a practicing doctor for long, but was appointed professor of medicine at Uppsala University in , eventually becoming rector of the school similar to a Dean in During his tenure, he was responsible for maintaining the university's Botanical Garden, a task he carried out with enthusiasm, arranging the plants according to his own Linnaean classification.
In the same year Linnaeus finished his doctorate, he published a brief pamphlet that would eventually revolutionize the fields of biology and scientific taxonomy. He kept revising and expanding it for the rest of his life. It proposed a radical new approach to the ordering and classification of plants and animals. His system was hierarchically ranked, meaning that organisms were grouped into successively larger groups based on morphological traits that is, physical attributes. At the broadest level, the classification system was divided into three broad kingdoms: animals, plants and minerals the mineral designation was subsequently dropped.
These categories were further subdivided into increasingly specific designations, which included "classes," "orders," "genera," and "species. Related: Ancient mystery creature that defied classification is Earth's oldest animal. Scientific classification during the 18th century was chaotic, Beil said.
There were several different classification schemes in vogue and new specimens were being discovered all the time, especially from areas outside Europe that were the focus of European colonization. These specimens were scrutinized by scientists from different countries, each of whom used his own method and terminology.
This led to many of the same species acquiring several different names, frequently in different languages.
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