Chapter 7 Evolution
- The origin of life can be understood only against the background of origin of earth.
- Most scientist believe in chemical evolution I.e. formation of biomolecules preceded the appearance of the first cellular forms of life.
- The subsequent events as to what happened to the first form of life are a conjectured story based on Darwinian ideas of organic evolution by natural selection.
- Diversity of life forms on earth has been changing over millions of years.
- It is generally believed that variations in a population result in variable fitness. Other phenomena like habitat fragmentation and genetic drift may accentuate these variations leading o appearance of new species and hence evolution.
- Homology is accounted for by the idea of branching descent. Study of comparative anatomy, fossils ad comparative biochemistry provides evidence for evolution