1. EVIDENCE FOR THE THEORY OF EVOLUTION
3. homologous structures and common ancestry
Copyright Pearson Prentice Hall

2. Copyright Pearson Prentice Hall
Homologous Body Structures
Structures that have different mature forms but develop from the same embryonic tissues are called homologous structures.
Copyright Pearson Prentice Hall

3. Copyright Pearson Prentice Hall
Evidence of Evolution
Homologous Structures
Turtle
Alligator
Bird
Mammal
The limbs of these four modern vertebrates are homologous structures. They provide evidence of a common ancestor whose bones may have resembled those of the ancient fish shown here. Notice that the same colors are used to show related structures. Homologous structures are one type of evidence for the evolution of living things. Homologous structures are one type of evidence for the evolution of living things.
Ancient, lobe-
finned fish
Copyright Pearson Prentice Hall

4. Copyright Pearson Prentice Hall

5. Copyright Pearson Prentice Hall
Evidence of Evolution
Not all homologous structures serve important functions.
The organs of many animals are so reduced in size that they are just vestiges, or traces, of homologous organs in other species.
These organs are called vestigial organs.
Copyright Pearson Prentice Hall

6. EVIDENCE FOR THE THEORY OF EVOLUTION
4. Similarities in early development, or embryology
Copyright Pearson Prentice Hall

7. Copyright Pearson Prentice Hall
Similarities in Embryology
The early stages, or embryos, of many animals with backbones are very similar.
The same groups of embryonic cells develop in the same order and in similar patterns to produce the tissues and organs of all vertebrates.
Pharyngeal
pouches
Post-anal
tail
Chick embryo (LM)
Human embryo
Copyright Pearson Prentice Hall

8. Copyright Pearson Prentice Hall
Evolutionary Theory
Evolutionary Theory
Scientific advances in many fields of biology, geology, and physics have confirmed and expanded most of Darwin’s hypotheses.
Evolutionary theory continues to change as new data are gathered and new ways of thinking arise.
Copyright Pearson Prentice Hall