The Origin of Life

1. The Origin of Life Biology I In the beginning……..

2. Origin of Life Background • The principle of biogenesis, which states that all living things come from other living things, seems very reasonable to us today. Before the seventeenth century, however, it was widely thought that living things could also arise from nonliving things in a process called spontaneous generation. This seemed to explain why maggots appeared on rotting meat and why fish appeared in ponds that had been dry the previous season- people thought that mud might have given rise to fish. In attempting to learn more about the process of spontaneous generation, scientists performed controlled experiments.

3. Chemical Evidence • Aleksanr Oparin: Suggested that life developed slowly when the molecules in the oceans were heated by the sun and electrified by lightning making molecules necessary for life.

4. Fossil Evidence • Scientists have learned much about the early history of the earth by knowing the age of certain fossils. • It has helped us to see how life has changed. • There are gaps in the fossil record and fossils have not been found for every organism that has ever lived on earth.

5. Developing a theory of Evolution Jean Babtiste Lamark • Suggested that a change in structure followed a change in the job. • An animal may acquire a new trait because of an environmental need and then pass it on to their offspring. • Example: Giraffes grew long necks to reach the food higher in the trees.

6. Charles Darwin • Suggested the theory of Natural Selection. • The process by which those organisms best suited to their environment will survive and reproduce. • Example: Giraffes born with longer necks (possibly by mutation) could reach the food above the shorter-necked giraffes, therefore survived and passed on that trait to their offspring.

7. Patterns of Evolution

8. Coevolution • The change of 2 or more species in close association. • Predators and prey, parasites and their host, plant-eating animals and plants sometimes co-evlove. • Example: Nectar-drinking bats have coevolved with the flowers they drink. • The bats muzzle has become long and slender to get inside of the flower and the flower’s shape has evolved to allow the hair on the bats face to pick up pollen and distribute it to the next plant.

9. Convergent Evolution • The environment selects similar phenotypes, even though the ancestral types were quite different. • Example: Sharks and porpoises. Sharks are fish and porpoises are mammals, yet many features of these animals are similar, such as their fins and streamlined bodies.

10. Divergent Evolution • Two or more related populations or species become more and more dissimilar, usually because of different habitats. • This can result in the formation of a new species. • Adaptive radiation- many species evolve from a single species Example- Galapagos finches • Artificial selection- breeding of organisms by humans for specific phenotypic traits Example- House cats are the same species but different breeds