1. Evolution

2. Theory of evolution
Many of the species we know on Earth today existed in very different forms millions of years ago. The change and development of a species over the course of many generations is called evolution.

3. Theory of Acquired Characteristics
Jean-Baptiste Lamarck formed one of the first theories of evolutions. Lamarck proposed that traits developed over the course of an organism’s lifetime were passed down to the next generation.

4. Lamarck Cont.
Lamarck believed that microscopic organisms appear spontaneously (Spontaneous Generation) from inanimate materials and then transmute, or evolve, gradually and progressively into more complex forms through a constant striving for perfection. The ultimate product of this goal- oriented evolution was thought by Lamarck to be humans. He believed that evolution was mostly due to the inheritance of acquired characteristics as creatures adapted to their environments.

5. Lamarck Cont.
For example, Lamarck thought that giraffes evolved their long necks by each generation stretching further to get leaves in trees and that this change in body shape was then inherited. Likewise, he believed that wading birds, such as herons and egrets, evolved their long legs by stretching them to remain dry. Lamarck also believed that creatures could develop new organs or change the structure and function of old ones as a result of their use or disuse.

6. How quickly do things evolve?
Although Scientists agree that species change and organisms adapt, there are different views on how fast it happens. Some think evolution tends to be a really slow process that takes millions of years (Gradualism). Others think evolution happens in spurts (punctuated equilibrium). There is evidence to support both theories.

7. Evidence of Evolution Fossils Structural cues DNA Clues
Fossils can preserve the structure of an organism in many ways, and they give us a really good idea of what certain organisms looked like through history.
The fossil record isn’t complete because conditions needed to preserve an organism as a fossil are rare so there may always be gaps in the fossil record.
Structural cues
DNA Clues

8. Evidence of Evolution- Embryology
One Area of evidence for evolution is embryology, the study of embryos. Comparing the embryonic developments of multiple species helps us understand that many species share characteristic in their early development
Ex. Vertebrates have muscles arranged in groups of bundles and a tail. They also each have hard protective coverings over the brain.

9. Evidence of Evolution- Structural Cues
Vestigial structures are body structures that no longer have a function. They provide more clues about evolution. It is a leftover from an ancestor species that was once a functioning and vital part of the ancestor species.
Ex. Humans have tailbone, appendix and tonsils all of which are vestigial structure.

10. Evidence of Evolution- DNA
Scientists can compare the DNA of different species in order to find similarities which can tell us information about common ancestry. Mutation rates can also be used to track the changes in species over time.

11. Review The main points of Natural selection
Individuals of the same species have different traits.
Organisms compete with one another for survival
Individuals with traits that help them survive reproduce more successfully. These successful individuals pass their helpful traits down to their offspring.
In time, individuals with the helpful variation may become a separate species as their numbers grow, or if they become isolated from the original population.

12. Definitions
Variation: genetic differences between individuals within a species
Adaptation: inherited variations that make an organism better suited to its environment
Natural Selection: Species change over time to adapt to their environment. The trait that gives an organism a survival advantage is passed on to its offspring when it reproduces.