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Plato & Aristotle Theory
Socrates' students Plato and Aristotle believe the world and all of its organisms are perfect and unchanging.
Plato (427-327BCE): He believed that all living things were made by a craftsmen named Demiargos and were all modeled to represent an imperfect replica of a perfect, heavenly, model
Aristotle (384-322BCE): He was the first to come up with 'The Great Chain of Being'. This suggested that species were placed in a heirachy from lowest at the bottom (worms) and the highest at the top (God) -
John Ray's Theory
John said that every different animal and plant was a different species and you can define them by physical characteristics. All creatures were made by god but had changes because of local conditions. -
Carolus Linnaeus's Theory
He thought that creatures changed according to God's divine plan. -
Buffon's Theory
Geroges-Louis Leclerc, Comte de Buffon is the first man to publicly challenge the belief that life never changes and that the wordl is 6000 years old. He studies the anatomy of animals and notes the similarities between species. He theorizes that they probably had common ancestors. It this is the case the world is much older than 6000 years. -
Maupertuis's Theory
He said that natural modifications could occur over many generations and could create a new species. -
Erasmus Darwin's Theory
Charles Darwin's father thought that all warm-blooded animals came from the same, single micro-organism. -
Cuvier's Theory
Geroges Cuvier, a paleontologist, studies fossils and notes the appearance and also disappearance of species in different layers of fossils. This must mean species change and events cause the death of some species. He calls these catastrophic events "revolutions". -
William Paley's Theory
He worked off of John Ray's ideas, he still thought complex adaptations were the work of God's divine design. -
Lamarck's Theory
Jean-Baptiste Lamarck observed a "line of descent" in organisms and their offspring, and believed that hypothesized that characteristics that were developed or built up over an organism's life could be passed on to its offspring. He wrote the book "Philosophie Zoologique". -
Lyell's Theory
Geologist Charles Lyell disagrees with the theory of "revolutions", and instead reasons that changes to species must be very stubtle and take a significant amount of time, because these changes aren't usually ovservable in the span of a human life. He also questioned changes in populations. -
Darwin's Theory
Naturalist Charles Darwin went on a several-year voyage around South America on the HMS Beagle. He made many geographic observations, involving the distinct adaptations that animals in different areas had developed. He spent the next 20 - 25 years after his voyage developing his theories, and finally published his work when he realized his ideas were becoming more commonly known. -
Charles Darwin Sets Sail on the HMS Beagle
It was a 5 year voyage around th world, specifically around the coast of South America. Darwin came up with his theory of evolution by natural selection while in the Galapagos Island when he saw the different species of finches and tortoises. -
After The HMS Beagle
Charles Darwin spent 15 years after his voyage conducting extensive experiments with plants to find evidence to back up his theory. -
The Structure and Distribution of Coal Reefs
Charles Darwin published 'The Structure and Distribution of Coal Reefs'. He worked on this for 3 years. -
Charles Darwin's Final Research
He spent 8 years of work on studying barnicles and when he recieved a letter from Wallace he finally published his 240 page essay on natural selection (The Origin of Species). -
Alfred Russel Wallace's Theory
He sent a letter to Charles Darwin with the same ideas of natural selection. -
The Origin of Species
Charles Darwin publishes this book about natural selection because he knows that other people, like Wallace, are coming up with similar ideas about natural selection. -
Gregor Mendel's Theory
He thought that traits could be predicted in animals by sorting out their genes. -
August Weismann's Contribution to the Theory of Evolution
He discovered the difference between gamete cells and somatic cells. He realized that the traits were passed on through the gamete cells. -
Hugo De Vries
He studied cells and realized that some variations are a result of mutations in cells. -
James Watson & Francis Crick
They discovered the structure of DNA which proved the inheritance of traits.
