Biological Classification

History

History of biological classification is as old as human culture. Human beings started giving names to the animals and plants and classified them on the basis of their use Our Vedic literature (2500 BC to 650 BC) recorded about 740 plants and 250 animals. The first attempt of classification is observed in Chandyoga Upanishad, which classified animals into three categories (1) Jivaja (viviparous), eg. mammals (2) Andaja (oviparous), eg, birds, reptiles, insects and worms (3) Udbhija (vegetable origin), eg, minute animals In Post-Vedic Indian literature, such as Susruta Samhita, all living forms are classified into 5thavara (immobile). Le, plants and Jangama (mobile), eg., animals. Plants were further divided into Vanaspati (fruit yielding, nonflowering plants), Vriksa (fruit yielding, flowering plants) and Osadhi (plants provide medicine). Susruta Samhita also classified animals into Kulacara (herbivores that frequently visit river banks, eg. Elephant, Buffalo, etc., Matsya (fish), Janghala (wild herbivorous quadrupeds), eg, Deer, Guhasaya (carnivorous quadrupeds), eg. Tiger, Lion, etc.

Greek scholars, Hippocrates (460-377 BC), Aristotle (384-322 BC) and ancient Greeks of 4th and 3rd century BC made the earliest known efforts to classify living organisms into plants and animals on the basis of some common characters. Theophrastus (370-285 BC), the Father of Botany in his book Historia Plantarum classified plants on the basis of their habit, form and texture into four categories: Trees, shrubs, undershrubs and herbs.

 Prior to this, organisms were classified as edible or inedible or as food animals, fur animals or as field crops and fruit trees, fibre plants, weeds, etc. This value-based classification is called practical classification.

Early Greeks classified animals and plants on the basis of habit and habitat, such as aquatic,
terrestrial, aerial or as carnivorous, herbivorous or as oviparous and viviparous, etc. Aristotle
classified living organisms on the basis of morphological similarities and created groups and species. This system of classification based on external morphological similarities is called
Artificial System of Classification. 

In India, Charak (1st century AD) is known as the Father of Ayurveda. He listed about 340 plants and 200 animals of medicinal importance in his book Charaka Samhita on Indian medicines, John Ray, English naturalist (1627-1705), introduced the Concept of Species and Natural System of Classification based on morphological similarities. He collected about 18,000 plant species from various parts of Europe and described them in three volumes of Historia Generalis Plantarum.

In the last few decades, new methods of assessing relationship, such as comparison and evolution of DNA sequences have totally revolutionised the taxonomic approach. Now chromosome number, nucleotide sequence and protein structure are used to trace evolutionary relationship in different groups of organisms.

The great Swedish naturalist of 18th century, Carolus Linnaeus (1707-78) is called the Father of Taxonomy. He introduced the current system of naming organisms with two names. This system of naming plants and animals is known as Binomial System of Nomenclature. He described about 5,900 species of plants in his book-Species Plantarum (1753) and about 4,200 species of animals in his book Systema Naturae (1758).