3 Main Questions:
- What is evolution?
Descent with modification; the idea that living species are descendants of ancestral species that were different from the present day one.
- What is strata?
A rock layer formed when new layers of sediment cover older ones and compressed them.
- What is uniformitarianism?
The principle stating that mechanisms of change are constant over time
5 Main Facts:
- During the voyages of the Beagle, Darwin observed many examples of adaptions, characteristics, of organisms that enhance their survival and reproduction in specific environment.
- Darwin viewed the history of life as a tree, with multiple branchings from a trunk out to the tips of the youngest twigs.
- Darwin proposed a mechanism, natural selection, to explain the observable patterns of evolution.
- An organism's trait can influence not only its own performance, but also how well its offspring cope with environmental challenges.
- One subtle but important point is that although natural selection occurs through interactions between individual organisms and their environment, individuals do not evolve.
Diagram:
This evolutionary tree of insect and plant eater and thier relatives is based mainly on fossils - their anatomy, older of appearance in strata, and geographic distribution. Most branches of descent ended in extinction.
Summary:
A century and a half ago, Charles Darwin was inspired to develope a scientific explanation for these three broad observations. When he published his hypothesis in The origin of species, Darwin ushered in a scientific revolution the era of evolutionary biology.
Evolution as descent with modification, a phrase Darwin used in proposing that Earth's many species are descendants of ancestral species that were differnent from the present day species.
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