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Explore the pivotal journey of Charles Darwin on the HMS Beagle, a five-year expedition that profoundly influenced his career and laid the foundation of evolutionary theory. While Darwin didn't originate the idea of evolution, he is recognized as its father. Discover how evidence from fossils, observed species in various environments, and the influence of thinkers like Malthus led him to formulate the theory of natural selection. Unravel the contributions of Alfred Wallace and the significance of Darwin's landmark book, "On the Origin of Species," published in 1859.
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Adventures in Evolution • http://www.youtube.com/watch?v=vmphlbRhLu8
HMS Beagle • Darwin did a 5-year voyage on the HMS Beagle • Darwin stated “ the voyage of the Beagle has been by far the most important event in my life and has determined my whole career”
Did Darwin invent the idea of evolution? • NO. But he is considered the father of evolution. • In 1830s people assumed that species were fixed and unchanging • Explorers and naturalists were discovery various plants and animals • Fossils were providing evidence of some species that lived in the past • Anatomists noticed physical resemblances between different species
Old ideas to explain how species changed were flawed • Lamarckianism, named after Jean-Baptiste Lamarck • Suggested that species could change through inheritance of acquired characteristics. • Giraffes developed their long neck by continually stretching them to feed on tall giraffes. • Once acquired, a giraffe could then pass on trait to its offspring
Charles Lyell • Darwin read the work by geologist Charles Lyell, “Principles of Geology” 1833. • Book argued that earth was much older than the 6,000 years • Incremental forces operating over a vast expanse of time
Darwin’s Voyage • Ideas of evolution really started when Darwin unearthed a complete fossil of a giant sloth embedded in a cliff, below a layer of seashells • Animal lived in the area before it was an ocean environment and had lived long time ago • No living animal in present day looked like the creature found. Where had they gone? • Reasoned that when the landscape changed the animals had been unable to adapt and became extinct. • Noticed that South American species resembled European ones, despite different environments
Darwin’s voyage • He evidence did not support a species perfectly adapted to its environment. • Galapagos Islands, observed small birds, finch • He realized that the birds were all closely related species of finch. – different size and shape of beak.
When he returned he read the a book by Thomas Malthus that described how hunger, starvation, and disease would ultimately limit human population growth (1798) • Limitation would lead to competition for resources • Favorable variations would be preserved and unfavorable ones destroyed • Competition, reproductive success would lead to a species becoming more adaptive to environment.
Natural Selection • Darwin’s original contribution to the theory of evolution he called descent with modification. • The mechanism of evolution is natural selection. • In 1844, Darwin developed his ideas into a 200 page manuscript
Alfred Wallace’s Thought • Wallace was also fascinated by natural history and adventure. • Was he rich? • He traveled to Brazil, to mouth of Amazon River • He also noticed different species of sloth monkey and other species. • What happened to his notes? • Wallace was able to write an article about new species but it did not mention a mechanism. • What happened to him next? • He worked out a mechanism of evolution and sent the paper to whom?
Darwin’s Book • Wallace stimulated Darwin to finish his book • Darwin finished his book on Evolution. • “On the Origin of Species by Means of Natural Selection” published in 1859
