Scientific Contributions to a Theory of Evolution

Lesson 3

Pre-Darwinian Times• Aristotle (circa 400 BCE)• He believed in the Scala

Natura (Scale of Nature).

• All living things were arranged on a scale of increasing complexity with humans at the top.

• He felt all species were perfectly adapted to their environment and there was no evolution/change.

Pre-Darwinian Times

• Carolus Linnaeus (1707-1778)

• He came up with the binomial nomenclature system of taxonomy we use today in which each species gets a scientific name based on its genus and species.

Ornithorhynchus anatinus

Geoges-Louis Leclerc de Buffon (1707 – 1788)

• One of the first to challenge that life forms are unchanging

• Noted similarities between apes and humans

• Suggested Earth may be older than 6000 years, which was widely believed at the time

Georges Cuvier (1768-1832)

• k He was a paleontologist

• He found that rocks deeper in the Earth had much different fossils than anything that was walking around during his life time.

Georges Cuvier (1768-1832)• He did not believe in evolution. He believed in catastrophism.

• Catastrophism is the belief that each strata of rock contained different fossils because it was associated with a catastrophic event (i.e. the flood in Genesis)

• The Earth was a place where catastrophes happened and different animals emerged afterwards.

James Hutton (1726-1797)

• Introduced gradualism.

• Gradualism states that geological changes are slow and gradual and take long periods of time.

Charles Lyell (1797-1875)

• Famed geologist whose book, Principles of Geology, Darwin took with him on the HMS Beagle.

• He brought up the idea of uniformitarianism.

• Uniformitarianism states that geologic processes have not changed throughout earth’s history.

Why are these dead guys important???

• Their theories kept stretching the time that Earth was formed further and further back in time, which conflicted with religious teachings, but made more sense scientifically.

Jean Baptiste Lamarck (1744-1829)

• He placed fossils in an evolutionary context and published a theory of evolution in 1809. 

• His theory used two common ideas of his time:

• 1) Use and disuse - parts of the body used on a regular basis become larger and stronger; those not used deteriorate.

                                 • 2)  Inheritance of these acquired

characteristics (I.e., the modifications) are passed onto the offspring.                        

• Lamarck’s theory was based on observations of fossils, but gave no mechanism for evolution. 

Lamarck

• Today we know that Lamarck’s was flawed

• Ex – your vision does not improve the more you use your eyes

• It is possible to stretch your neck slightly, but it will not alter you DNA and your children will not be born with longer necks

• However, was he so wrong, given what we know about eipgenetics???

Lamarck - Contributions

• All species evolve over time

• A species evolves in response to its environment and becomes better adapted to that environment

• Changes are passed on from generation to generation

Charles Darwin

The Journey

• Returned to England in 1836 after a 5 year trip

• In 1837 – started to write his first notebook

• Some of the most compelling evidence for evolution comes from biogoegraphy – observed geographic patterns of distribution of species

Darwin’s Hypothesis• Realized that patterns he had observed regarding

the distribution of species, both living and extinct, were evidence that species might have evolved

• Hypothesized that remote oceanic islands became populated by species that arrived by water or air

• After the species became established, many evolved into new species over time

Galapagos IslandObservations from the Galapagos Islands

Darwin’s hypotheses regarding remote islands

Many species of plants, birds insects, and, in some cases reptiles

Only these kinds of organisms are able to reach remote islands by crossing large expanses of open ocean

No native amphibians and very few land mammals

Amphibians and most mammals are unable to cross open ocean and will not be found in remote islands

Many unique species found nowhere else on Earth

Over time, ancestral species have evolved into new geographically isolated species

Unique species most closely resemble species on the nearest continental land mass

Unique species are descendents of ancestral species from the nearest continental land masses and will exhibit some similarities

Darwin observed fossils of extinct animals, and observed they looked similar to living animals

• Read pages 328-330 and make notes

• Pg 327, Q 2-6

• Pg 331 Q 1, 4,5,6,7,8,11,12,15