Evolution Theory Of Evolution

Introduction

Biological evolution is descent with modification. Theories of evolution have their roots in early Greek and Roman culture. Before seventh century B.C.E., people believed that supernatural forces were responsible for life. Philosophers Plato and Aristotle argued against this doctrine. They used logic to explain the origins of life. It was commonly accepted that the earth was only a few thousand years old, species were immutable, and that life is arranged linearly. In the seventh century, naturalist John Ray used the term “species” as the basic unit of classification. In the eighteenth century, Carolus Linnaeus created a hierarchical classification system for organizing species based on resemblance using phylogenetic trees. In 1809, French theorist Jean-Baptiste Lamarck published his theory of inheritance of acquired traits. In 1830, Charles Lyell introduced uniformitarianism as the mechanism for evolution; the theory that states that geologic change is relatively constant. In the mid-nineteenth century, Alfred Wallace and Charles Darwin both individually conceived natural selection as the mechanism for evolution. Darwin received credit for the theory of natural selection because he published his book, On the Origin of Species, before Wallace. In 1865, Gregor Mendel is the founder of modern genetics through his work with pea plant crosses. To this day, the work of Mendel and Darwin are widely accepted.

The Important Players in the History of Evolutionary Thought

Aristotle

In 300 B.C. Greece, Aristotle made his contribution to evolutionary thought. Aristotle organized living organisms hierarchically. This concept was known as scala naturae, or the Great Chain of Being. With plants at the bottom, Aristotle’s scala nat...

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...They discovered that when the climate was dry, there were no major changes in the brain, but when the climate changed, there were changes in the size of the brain. As soon as the size of the brain increased, stone tools appeared.

Homo erectus was the first to leave Africa, hunt, make fire, and create societies. Homo erectus lived 1.3 million years ago in the Great Rift Valley. Homo erectus evolved to have thinner arms, longer legs, and bigger brains. This is considered to be a huge evolutionary step away from ape bodies, to more human bodies. In Northern Kenya, Turkana Boy’s skeleton was found. At 5 foot 3 inches, Turkana Boy had a build closer to a human’s than to an ape’s. Turkana Boy represents the first true human. Although he was one of the first humans, he was still very primitive. Turkana Boy had a lower forehead, and a smaller brain capacity than a human.