Name 2/03/10#43 Section 6.3 Notes

Many types of evidence

support evolution

fossil

biological

genetic

What is a scientific theory?

• Scientific theory - widely accepted statement based on scientific evidence that helps explain and predict natural phenomena

Can you list any scientific theories?

• Theory of evolution• Atomic theory• Theory of relativity• Big bang theory• The germ theory of illness

What do you need to prove a theory is accurate?

• Evidence that confirms the theory

Can theories change? If so, how?

• Yes, theories can change if new evidence becomes available.

What evidence supports the theory of evolution?

• The theory of evolution has been built on three sources of evidence: fossil, biological and genetic.

How does fossil evidence support evolution?

• Fossil evidence shows that two species with a common ancestor can develop differently

• ancestor – an early form of an organism from whichlater forms descend• Example: The glyptodon resembles the modernarmadillo found in South America today.

How does biological evidence support evolution?

• Scientists use biological evidence by studying the structure and development of living things.

• Scientists focus three things:-Vestigial organs-Homologous structures-Embryonic Development

Vestigial organs

• Vestigial organs are physical structures that are no longer useful to a living organism, but may have existed as fully developed structures in an ancestor.

Vestigial organs

• Human examples:-tail bone -appendix -wisdom teeth

Homologous Structures

• Homologous Structures – Many different species share similar body structures.

• However, these structures are used differently by each species.

• The similarity shows that the organisms share a common ancestor.

• Label the following structures found in each organism:1) carpals 2) radius 3) humerus 4) phalanges 5) metacarpals 6) ulna

3

2

6

1

5

4

Homologous Structures

Embryonic Development

• There are many organisms that look very similar during embryonic development (earliest stages of life).

• As the organisms develop, they look less and less alike.

• These similarities again show that the organisms share a common ancestor.

How does genetic evidence support evolution?

• Similar organisms have very similar genes

• Less closely related organisms have genes that are much easier to tell apart.

• The similar patterns in DNA show the organisms share a common ancestor.