Unit 5 - Evolution

Evolution of Man

Adaptations:
An adaptation is when an organism slowly changes it's physical appearance or it's genes. Evolution is the adaptations of millions of organisms over billions of years. Most adaptations are because the organisms within the species that don't adapt die out so you only have the adapted ones. This is called "Survival of the Fittest".
Let's use the giraffe as an example:
Lamarck (a scientist) believed that the short-necked giraffes kept stretching their necks until they were long enough to reach the high leaves on trees. We know that most of the time when you change your phenotype (refer to unit 3 post), it does not change your genotype. That's like saying: if you were to lose an arm doing something (let's say in combat), your offspring would only be born with one arm. That's insane!

Now most/all scientists believe that the giraffe used to have a short neck and ate off of the lower shrubs. Competition for the food lower to the ground got so high that the giraffes with short necks started to die out. Scientists believe that the short neck giraffes died while the ones with slightly longer necks lived a little longer to reproduce and their offspring had longer necks. This continued until all of the short neck giraffes were dead. This is an example of "Survival of the Fittest" and adaptation.

Fossils:

Fossil Record

We all know the museum has dinosaur bones put together and on display. These bones are called fossils. Fossils are the preserved remains or traces of animals, plants, and other organisms from the remote past. Scientist keep a record of fossils, known as the Fossil Record. The Fossil Record show us how species of organisms have changed over time. It also helps us keep track of what organisms may have had a common ancestor.