This tutorial introduced the challenges of defining life, and how evolution and natural selection can explain the great diversity of life on earth. We also looked at the age of the earth and how the fossil record, along with radiometric dating techniques, can help us understand the story of life on earth.
Our solar system formed about 4.5 billion years ago. It appears that Earth began forming shortly thereafter, and evidence suggests that life first appeared by the end of the first billion years (about 3.5 billion years ago). The available evidence indicates that evolutionary events have been ongoing over the last 3.5 billion years and that these processes have led to the diversity of life we see around us today. In thinking about evolution, remember that all living species represent "modern" forms of life. The challenge that faces evolutionary biologists is to reconstruct events that have occurred in Earth's distant past, and to infer the nature of ancient events that have contributed to the current diversity of organisms.
Scientists can use a variety of techniques to determine the age of these fossils and piece together the history of life on earth. We focused on learning about radiometric dating techniques which are powerful techniques that have helped us learn more about the history of life on earth.