In the first edition of The Origin of Species, Darwin never used the word __, but used __, a phrase that summarized his view of life. Darwin perceived __ in life, which he attributed to the descent of al organisms from an ancestor that lived in the remote past. He also thought that as the desendants of that ancestral organism lived in various habitats over millions of years, they had accumulated diverse modifications, or __, that fit them to specific ways of life. Darwin reasoned that over long periods of time, descet with modification eventually led to the rich diversity of life we see today.
- descent with modification