Common descent

Common descent is the biological theory that all observed life on Earth evolved from a common ancestor or ancestor species. The Last Universal Common Ancestor (LUCA) is the ancestor of this sort that was alive most recently.

The theory of common descent was proposed by Charles Darwin in his book The Origin of Species (1859), and later in The Descent of Man (1871).

More than a century later, discoveries in genetics confirmed this theory. It is now taken for granted by biologists. The LUCA is an ancient bacterium which appeared on the Earth about 3.5 billion years ago.

Relevance to Creationism

Some Creationists do not accept the theory of common descent, arguing that humanity was created by God in distinct act of creation, whereas the rest of life evolved.

Evidence for common descent

All life on Earth stores its genetic code in DNA (except for a few viruses, which use solely RNA). In addition, much of this DNA is the same amongst very different species.