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Aristotle
Aristotle proposed that species were fixed and unchanging. He also believed that organisms were organized on a scale ofincreasing complexity, with plants at the bottom and humans at the top. This concept is called the scala naturae. He proposed all this around 350 BCE. -
Divine Creation
The Roman Catholic Church, which dominated the lives of most Europeans, held the belief that all species were divinely crafted by God with a specific intention for each one. -
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Linnaeus and Binomial Nomenclature
During his lifetime, Linnaeus established the foundations for the modern naming system called binomial nomenclature. Father of modern taxonomy. -
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Lamarck's Idea
These dates are when Lamarck was born and died. Lamarck proposed that all species are descended from other species. He also proposed the "use it or lose it" theory, which states that body parts that animals use will grow larger and be passed to their offspring (this has been proven wrong because populations evolve, not individuals). -
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Georges Cuvier
Father of modern Paleontology. Most influential proponent of catastrophism. Catastrophism is a theory that earth has been affected by sudden disturbances. Cuvier believed that these sudden changes could account for the disappearance of sepcies and the appearance of new, slightly changed species. -
James Hutton
Proponent of gradualism. This theory claimed that earth is shaped by the cumulative effect of slow but continuous processes. Also called uniformitarianism. -
Malthus
Thomas Malthus argued that human populations always increase more quickly than the food supply. He published his ideas in An Essay on the Principle of Population. Darwin later related these ideas to natural selection. He noted that almost all species constantly overproduce as an attempt at passing on their genes more successfully. -
Fossils
It is understood that fossil animals found in older rocks are simpler and smaller than those in younger rocks. -
Selective Breeding
In the late 1700s and early 1800s, farmers in Britain were learning how to use selective breeding to produce farm animals with the characteristics they wanted. This is an example of artificial selection done by humans.We now use these same methods, though much more thoroughly developed, to create better food and livestock. -
Georges Cuvier
Georges Cuvier in the early 1800s produced fossil bone evidence but thought that fossils were caused by "catastrophes" ie exctinction. -
Lamarck
Lamarck proposed that species change through time, but he could not say how long it would take. -
Charles Darwin is born!
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Alfred Russel Wallace is born!
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Charles Lyell
Charles Lyell showed how rock and fossil evidence formed a continuous pattern through long geological time. He published Principles of Geology. He was a proponent of gradualism and uniformitarianism, the belief that earth is being continuously changed by ongoing processes still happening at the same rate today. Darwin was heavily influenced by his ideas and discovered that species were also gradually changing. Lyell's observations also suggested that the earth was older than believed. -
Departure
Charles Darwin left England on the HMS Beagle. -
Destination
The HMS Beagle arrives at the Galopagos Islands. It is here that Darwin observed the subtle differences in species on different islands. It is because of his time spent here that Darwin came up with his theory of descent with modificationa and eventually the process of natural selection. -
Darwin vs. Wallace
Darwin received a monograph from Wallace that basically summarized all of his previous findings about natural selection and the appearance of species. He had been hesitant about publishing his work before because of the church belief in divine creation. However, he was motivated to publish his work early after receiving the monograph from Wallace, probably because he wanted the credit from his work. -
Natural Selection
Natural selection as proposed by Darwin needs a way for variations to be inherited in living things. His theory of natural selection states all organisms attempt to pass thier genes on to offspring, and those that do this the most are deemed fitter. He also claimed that the organisms who survived in their environment (winning competitions for natural resources) often had desirable traits that allowed them to have an advantage and were then passed to their offspring. -
The Origin of Species
Darwin finally published his work in The Origin of Species. All 1,250 copies were sold out on the first day. -
Wallace and Darwin
Wallace and Darwin working around 1860 thought that natural selection would take a very long time - perhaps millions of years to show evolutionary change. -
Earth's Age
Around the late 1800s and early 1900s, the age of the earth was very unclear but estimates ranged from 3 million years old to 2300 million years old. -
Mendel
Mendel's work on genetics was used to show how variation was inherited and from this an understanding of genes developed. -
Catholicism and Evolution
Pope Pius XII claimed that evolution did not necessarily contradict religious beliefs about creation. -
Earth's Age
Now we believe the earth to be nearly 4.5 billion years old.
