Evidence for Evolution Key Terms: Fossil Relative dating Radioisotope dating/carbon dating Half Life Homologous structures Analogous structures Vestigial structure Embryology Embryo Biogeography Comparative morphology

Fossil Evidence of Evolution Fossils: the remains or traces of organisms that live in the past (studied by paleontologists) Relative dating: a means of identifying the age of a fossil or rock by comparing it to another fossil or rock

Fossil Evidence of Evolution Half-life: the amount of time needed for one-half of a radioactive element to decay Radioisotope dating: measures the age of a material by comparing the amount of a radioactive form of an element contained in the material with the amount of decay product Carbon dating: using carbon to determine the age of a fossil

Physical Features: Comparative Anatomy Homologous structures: body parts of different organisms that have a similar structure, but may have different functions

Physical Features: Comparative Anatomy Analogous structures: body parts that have a similar function, but not a similar structure

Physical Features: Comparative Anatomy Vestigial structures: body parts that do not seem to play a major role in an organism’s life functions

Physical Features: Comparative Anatomy Comparative morphology: a branch of science in which the structures of living things are compared to understand better the development and relationship among species Embryology: the study of embryos or animals before birth Embryo: an early stage in the development of an organism Biogeography: distribution of species on Earth over the course of history

Biochemical Evidence for Evolution All organisms have DNA. DNA directs the production of proteins, which are made up of amino acids. Scientists study both the sequences of bases in DNA and the resulting proteins to compare organisms. The more closely related two organisms are, the more similar the components of these molecules are.