A Brief History of Classification
 

It is interesting to think that early historians did not view the similarities and differences among organisms as consequences of evolution, but at the same time still sought a mechanism to classify and organize biological diversity. In the year 1758, Carl Linn, a Swedish botanist, physician, and zoologist, proposed a system that has dominated classification for centuries. This mechanism of classification is the famous binomial nomenclature. Linnaeus proposed that each species have two names: genus first word, capitalized) and species (second name, lowercase). An example of binomial nomenclature is Homo sapiens. [94]

 

Next, Linnaeus grouped genera into families. Those were then classified into orders, orders into classes, classes into phyla, and phyla into kingdoms, and kingdoms into the 3 classifications of living things, called domain. He then identified two kingdoms: Animalia (animals) and Plantae (plants). Due to the great efforts of Linnaeus and Charles Darwin in the studies of evolution, biologists have accepted those theories revolutionized the art of classification. [94]

The next major pioneer in classification was Thomas Whittaker; he proposed a "five kingdom" system in which three kingdoms were added to the animals and plants: Monera (bacteria), Protista, and Fungi, in addition to the kingdoms Animalia and Plantae. The way he specified why organisms were classified that way was by if they possessed a nucleus (eukaryotic) or not (prokaryotic). Because Monera are prokaryotic and hence are unicellar, they are distinct from the other four eukaryotic kingdoms. [94]

Then, the three muticellular kingdoms were differing in the way they acquire food; plants are autotrophs and use photosynthesis to capture energy from sunlight that is then used for food. Animals are heterotrophs and acquire nutrients by consuming plants or other animals. Fungi are also heterotrophs but, unlike animals, they generally break down large organic molecules in their environment by secreting enzymes. As can be noted, different organisms use different means of obtaining food. he five kingdoms system was a far more accurate and advanced than the previous system because it better portrayed the diversity of life. [94]