In evolutionary biology, a group of organisms share common descent if they have a common ancestor. There is strong quantitative support for the theory that all living organisms on Earth are descended from a common ancestor.
Charles Darwin proposed the theory of universal common descent through an evolutionary process in On the Origin of Species, twice stating the hypothesis that there was only one progenitor for all life forms and ending with "There is a grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one". The theory asserts that all currently living organisms on Earth share a common genetic heritage with each being the descendant from a single original species, though the suggestion of substantial horizontal gene transfer during early evolution has led to questions about monophyly of life.
The last universal ancestor (LUA) (also called the last universal common ancestor, LUCA), that is, the most recent common ancestor of all currently living organisms, is believed to have appeared about 3.9 billion years ago.
Read more about Common Descent: History
Famous quotes containing the words common and/or descent:
“It was common practice for me to take my children with me whenever I went shopping, out for a walk in a white neighborhood, or just felt like going about in a white world. The reason was simple enough: if a black man is alone or with other black men, he is a threat to whites. But if he is with children, then he is harmless, adorable.”
—Gerald Early (20th century)
““There is Hawthorne, with genius so shrinking and rare
That you hardly at first see the strength that is there;
A frame so robust, with a nature so sweet,
So earnest, so graceful, so lithe and so fleet,
Is worth a descent from Olympus to meet;”
—James Russell Lowell (1819–1891)