To explain: The reason for the belief of biologists that all living organisms of today have a common ancestor.
Introduction: Life on Earth has been hypothesized to have originated from simple inorganic molecules according to abiogenesis theories. The first and simplest life forms have been proposed to have evolved over time to various life forms of today found on the Earth.
Genetic code is a set of rules that translates the nucleotide sequence of DNA into the amino acid sequence of proteins. Almost all the organisms of today, including fungi, bacterial, plants, and animals utilize the same genetic code to translate information from their genetic material DNA into proteins. Therefore, all these organisms most probably must have descended from a common ancestor which was a primordial DNA-based microorganism, found more than 3.5 billion years ago. Therefore, biologists believe that all living things present on the Earth today share a common ancestor.