Kingdom | Definition & History of Kingdom

Kingdom Definition

As we all know that all living organism’s life is initiated from a single origin which further can be broken down or fragmented into lower level groups such as Phylum. In the taxonomical, the rank of the kingdom is unbiassed beneath the domain. In the taxonomical hierarchy, each sequential level exhibits the special group of organisms.


This type of construction has progressed or initiated from rare Taxon of kingdom consisting of 3 or 4 lower divisions. In the study of taxonomy, the kingdom is ranked on the second highest level and this level also has 6 divisions inside its structure. This is due to lodge the mounting numeral of familiar species and also gives explanations of how these species are interrelated with each other. Protista, Animalia, Plantae, and Fungi are three major kingdoms. The Archaea and bacteria are classified into one kingdom called Monera and some biologist considered them as a separate kingdom.


History of Kingdom in Taxonomy

In the 1700’s Carl Linnaeus was the first biologist who illustrates the premier life orders. On that time he classified all the living organisms into two foremost Kingdoms. Those named as kingdom Animalia and Plantae. But contemporary research related to genetics and microbiology exposed a new different perspective of the life of living organisms.

But in the 1990’s it was commonly acknowledged that all of the living organisms are classified into should into three domains. These domains are named as Archaea, Bacteria, and Eukaryota. This classification is done the major on the basis of difference in structure and configuration of the Cell and its endurance.


Definition of Domain in Biology

This three-Domain system is introduced by Carl Woese et al. in 1977. According to this biological classification, all the living organisms are divided into three cellular life forms which are named as Archaea, Bacteria and Eukaryota domains.

3 Domains and 6 Kingdoms

Several Taxon is present here which are truly phylum, but they don’t represent the complete kingdom. Advancement in the taxonomical study exposed that few sovereign phyla much resemble a kingdom. This perspective has changed its point of view. After 1990, by the passage of time, numerous versions of classification have been evolved from First taxonomy of Linnaeus’.In the early 1800s, it was documented small single-celled living organisms that are called Microorganisms and Protists have their own separate Kingdom. A fungus is separated from the kingdom Plantae. Newly, hereditary confirmation has exposed the Protists and Bacteria restrain a gigantic assortment of inheritance and adaptations. Due to steadily accumulation of information definitions and scale of ‘kingdom’ is relentlessly changing.


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Problems with Kingdom 

  1. Superlatively, each domain being a monophyletic group comprised of Ancestor and all the descendants who are extant and extinct both originated from a single common Ancestor.
  2. First, off all, it is unfeasible to be acquainted with all the vanished or extinct organisms. Due to this, there becomes huge area disbelief or uncertainty during the construction of Phylogenies. Phylogenies are basically the Trees of Life.

Tree of Living Organisms

While studying the Phylogenies you will definitely observe that many twigs or branched are well definite or defined but common point is that all branches have ancestry character in each other. Due to this, it’s very difficult to define a Kingdom. Deprived of the unswerving knowledge of the common ancestors we can’t able to draw a family tree line between Protista and Fung.


It is an uninformed description which highlights that from where does one lure or draw line between a Kingdom and domain. Archaea and Bacteria mutually considered as domains, while others are branches which belongs to the Eukarya.

Tree of Life diagram

Now a day due to advancement in this field computers has the ability to make phylogenies accurately in a very short time period.