Zimpapers Logo

Evolution is the change in the inherited characteristics of biological populations over successive generations. Charles Darwin was the first to formulate a scientific argument for the theory of evolution by means of natural selection. Evolution by natural selection is a process inferred from three facts about populations:

1. More offspring are produced than can possibly survive,

2. Traits vary among individuals, leading to different rates of survival and reproduction,

3. Trait differences are heritable.

Thus, when members of a population die, they are replaced by the progeny of parents better adapted to survive and reproduce in the environment in which natural selection takes place. This process creates and preserves traits that are seemingly fitted for the functional roles they perform. Natural selection is the only known cause of adaptation, but not the only known cause of evolution.

Other, non-adaptive causes of evolution include mutation and genetic drift

In the early 20th century, genetics was integrated with Darwin’s theory of evolution by natural selection through the discipline of population genetics.

The importance of natural selection as a cause of evolution was accepted into other branches of biology.

Scientists continue to study various aspects of evolution by forming and testing hypotheses, constructing scientific theories, using observational data, and performing experiments in both the field and the laboratory.

Discoveries in evolutionary biology have made a significant impact not just within the traditional branches of biology, but also in other academic disciplines (e.g., anthropology and psychology) and on society

History of evolutionary thought
The proposal that one type of animal could descend from an animal of another type goes back to some of the first pre-Socratic Greek philosophers, such as Anaximander and Empedocles.

In 1842 Charles Darwin penned his first sketch of what became “On the Origin of Species”. Other naturalists of this time speculated on evolutionary change of species over time according to natural laws.

Maupertuis, Buffon and Erasmus Darwin, Lamarck William Paley all dabbled in trying to explain the origin of life.

Partly influenced by “An Essay on the Principle of Population” by Thomas Robert Malthus, Darwin noted that population growth would lead to a “struggle for existence” where favourable variations could prevail as others perished. Each generation, many offspring fail to survive to an age of reproduction because of limited resources.

This could explain the diversity of animals and plants from a common ancestry through the working of natural laws working the same for all types of thing.

At the end of 1859, Darwin’s publication of “On the Origin of Species” explained natural selection in detail and in a way that led to an increasingly wide acceptance of Darwinian evolution. Thomas Henry Huxley applied Darwin’s ideas to humans, using palaeontology and comparative anatomy to provide strong evidence that humans and apes shared a common ancestry.

The Theory of Evolution does NOT say that people came from apes, but that apes and people evolved differently from a common ancestor. — Wikipedia