How would you describe Darwin's theory of common descent? What is some evidence that supports it?
Answers
Common descent describes how, in evolutionary biology, a group of organisms share a most recent common ancestor. There is "massive"[1] evidence of common descent of all life on Earth from the last universal common ancestor (LUCA).In July 2016, scientists reported identifying a set of 355 genes from the LUCA, by comparing the genomes of the three domains of life, archaea, bacteria, and eukaryotes.
Common ancestry between organisms of different species arises during speciation, in which new species are established from a single ancestral population. Organisms which share a more-recent common ancestor are more closely related. The most recent common ancestor of all currently living organisms is the last universal ancestor,[1] which lived about 3.9 billion years ago.The two earliest evidences for life on Earth are graphite found to be biogenic in 3.7 billion-year-old metasedimentary rocks discovered in western Greenlandand microbial mat fossils found in 3.48 billion-year-old sandstone discovered in Western Australia.All currently living organisms on Earth share a common genetic heritage, though the suggestion of substantial horizontal gene transfer during early evolution has led to questions about the monophyly (single ancestry) of life.6,331 groups of genes common to all living animals have been identified; these may have arisen from a single common ancestor that lived 650 million years ago in the Precambrian.
Universal common descent through an evolutionary process was first proposed by the British naturalist Charles Darwin in the concluding sentence of his 1859 book On the Origin of Species:
There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.