1. Basis for Classification

2. As we gather more evidence, classifications systems will change.
Modern classification uses evolutionary evidence from 3 areas.

3. 1. Anatomy
Scientists compare body parts that may be homologous parts; some are vestigial structures.
Homologous parts- similar because structures share a common ancestry ex- forelimb of vertebrates
Vestigial structures- structure no longer functioning, left over from ancestor. Ex- tailbone, appendix

5. Analogous parts- parts that do not share a common ancestor, but similar because are used for similar function. Ex- wings of bird and wings of butterfly.

6. Use fossil evidence to relate current organisms to extinct organisms.

7. 2. Embryology
Scientists compare developing embryos.

8. 3. Biochemistry
Scientists compare genetic codes ex-amino acid or DNA sequences
Also body chemistry ex- hormones, blood
The more nucleotide sequences organisms have in common the more related they are.

9. Species
Amino acid differences with human hemoglobin
Gorilla 1
Rhesus monkey 8
Mouse 27
Chicken 45
Frog 67
Lamprey
125