Introduction to Evolution

What is Evolution?

According to Biology-Online, evolution is ” The change in genetic composition of a population over successive generations, which may be caused by natural selectioninbreedinghybridization, or mutation.” What does that mean? In other words, evolution is genetic change over generations and populations. There are two types of evolution: microevolution and macroevolution.

Microevolution is any genetic change in a population over time, while macroevolution is based off of descent with modification and the genetic divergence of multiple species that arise from a common ancestor.

History of Evolution as a Science

How did evolutionary science emerge from a civilization heavily captivated by the 1800’s theological beliefs? Who were the famous biologists who shaped the trajectory of the Theory of Evolution?

When most of us think of evolution, we immediately think of Charles Darwin. Raised in England, Darwin was fascinated by nature and its budding organisms at a young age. He was a strong science enthusiast and often conflicted with the theological beliefs of his schools and university. Darwin later had the opportunity to board the Beagle ship as a naturalist. For 5 years, he surveyed various lands, plant and animal species, and fossils, and developed the idea of natural selection as the basis of evolution.

Darwin’s first sketch of an evolutionary tree in July  1837

–> Natural selection is the idea that organisms that are best adapted to their specific environment will more likely survive and pass on their favorable (and heritable) traits to their offspring. Over time, their genetic traits will be more likely to perpetuate throughout the population. And, “descent with modification” describes that all species and organisms descended from one or a few organisms. <–

Essentially, evolution is descent with modification.

Darwin, however, was not the only scientist who developed the idea of natural selection. There was also Alfred Russel Wallace.




Amnesia in Science History: Alfred Russel Wallace

The British naturalist Wallace had the same hypothesis of natural selection as Darwin had during the 1800s. The two worked independently from one another, but both formulated the same idea. In fact, Wallace sent Darwin his manuscript on natural selection while Darwin was working on his own writings on natural selection. Great minds think alike!


If Wallace also developed the idea of natural selection, why do most people think of Darwin instead of Wallace when talking about the Theory of Evolution? There were several factors. At the time, Darwin’s writings were more popular and promoted than Wallace’s, and had a larger group of support in the scientific community. Darwin also had a highly passionate advocate on his side, Thomas Huxley. Huxley, also known as Darwin’s Bulldog, was one of the many people who argued viciously for Darwin’s writings. The high popularity that surrounded Darwin caused Wallace’s presence to wane in comparison.


  4. Evolution: Making Sense of Life by Carl Zimmer and Douglas J. Emlen

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