 The circular Tree of Life. Moving clockwise: 12:00 to 9:00 is bacteria,
9:00 to 10:30 is archaea,
10:30 to 12:00 is all else. Common descent is thescientific theory that all living organisms on Earth descended from a common ancestor. Biologists have evidence that alllife developed from a common ancestor that lived just under 4 billion years ago, a concept accepted byvirtually all scientists working in the field. The structures and functions of all living organisms are encoded in the same basic nucleic molecules,DNA andRNA. Similarities inamino acid sequences between various organisms further suggest common descent, and thefossil record also shows cases in which one plant or animal type evolved into different typesover geological timespans. Creationists reject common descent as it implies an evolutionary model.Young Earth creationists reject it outright, beingBiblical literalists, insisting instead that life wassomehow created in just a few days, less than ten thousand years ago.Intelligent design proponents usually just claim that "we don't know what happened", though theymayaccept certain aspects of common descent as long as they are still allowed to claim that thedesigner messed with the genes and mutations along the way.Cdesign proponentsists generally believe in a hodgepodge of these positions. |
