Wednesday, January 25, 2012



Today we took notes during class.

The notes that we took today were about Darwin, his theory, and some of the other biologists.

A few things to know about Darwin (1809-1882)

  • he introduced the theory that all life is connected

  • he was one of the most influential scientists in the development of modern biology

  • published the Origins of Species- there are two main points to his book- "decent with modification" or evolution, and natural selection

  • he became a naturalist at 22 for a voyage around the world on the ship the HMS Beagle

  • he was mainly in the Galapagos Islands

  • while of the voyage he collected many specimens and noticed that as the animals strayed from the mainland, they began to adapt

  • he also found that after many generations, two populations could slowly adapt and change so much so that they eventually became two different species

Darwin explained the adaptations through natural selection and had 3 main points- overproduction, variation, and reproductive success. He also looked at artificial selection and came to conclude that by modifying a species through breeding would end up with the offspring or flowers/vegetables not looking like their ancestors. Artificial selection is when the species is being selected for certain traits and combined to get the desired offspring.

Many scientists during Darwin's day thought that the earth was relatively young, and was full of unrelated species. A few of the scientists to know from his time are-

-Anaimander(Greek)- thought all life arose in water and simpler forms preceded the more complex ones

-Aristotle(Greek)- thought species did not evolve (static)

-Buffon (1700's french)- thought world was much older than 6000 years, and that a species in a fossil could be an ancient version of a living species

-Lamark (1800's french)- said life evolved through adaptation, but had a strange theory on how life evolved. He believed the "Inheritance of Acquired Characteristics" was how life evolved. So if you don't use a limb, then you will pass that on to your offspring and that offspring won't have that limb. So if you didn't ever use your thumb, then your child wouldn't have a thumb.

-Lyell (Scottish)- earth was old and he supported the gradualism principle

-Wallace (British)- developed idea of natural selection identical to Darwin's, but Darwin published his first, so Wallace isn't as well known

Examples that support evolution:

  1. The fossil record- fossils can be used to research organisms from the past and are preserved in rocks. In the rocks, you can see different layers, and each layer is a different time period, as you dig further down, the fossils become older. Some of the oldest fossils are about 3.5 billion years old. The people who study these fossils are called paleontologists.

  2. Biogeography- the geographic distributions of species. ex. the animals that are found in Australia are found almost exclusively in Australia because it's isolated by the ocean.

  3. Comparative Anatomy- similar structure, but with different functions, and indicates that certain species came from a common ancestor (homology),vestigial organs or homologous structures can help trace back to a common ancestor, like in some animals such as the whale.

  4. Comparative Embryology- comparison the organisms while they are developing

  5. Molecular Biology- a common genetic code shared by organisms ex. there is less than a 2% difference in human and chimp DNA.

Over production of offspring, individual variation, and differential reproductive success all lead to adaptive evolution.


  • UP pg. 19-20

  • UP pg. 5 and pg. 13-16 are both due Monday

  • If you haven't read the Darwin article, CH 1, and CH 13

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