If, according to Darwin, human origin is from a monkey, who did the monkey originate from?
All modern primates derived from the proto-primates – tree dwelling squirrel-like mammals that emerged over 60 million years ago. Over the next 40 million years, primates evolved in diverging lines of descent. Over 20 million years ago one line diverged – that line line today has evolved into monkeys. The original line continued and again diverged several times to form the various apes. Some lines went extinct, others evolved into the modern species we see today. One of the latest lines of descent produced humans. Here’s a generalized illustration: http://www.ecotao.com/holism/evosummary.… Common ancestors exist at each branching. Note that there are several common ancestors between humans and monkeys – all of them were probably very apish looking.