Lecture 1: The history of life on Earth
The first lecture will be an outline of the long history of life on Earth. Earth formed four and a half billion years ago and there has been life on Earth for around four billion years. Attempting to summarize the great diversity of forms of life that has arisen over this immense timespan in a one-hour lecture is really an impossible task but a necessary one to provide background to the appearance of man (next lecture) very late in this long sequence.
Please review the lecture outline and slides before class.
Lecture Outline
12. Mesozoic, Age of Reptiles
13. K/T extinction
14. Cenozoic, Age of Mammals
15. Primates and Man
Concepts introduced in the first lecture
Lecture 1 ends with with a list of conclusions.
Lecture 2 will be on 'The Evolution of Man'
The first lecture will be an outline of the long history of life on Earth. Earth formed four and a half billion years ago and there has been life on Earth for around four billion years. Attempting to summarize the great diversity of forms of life that has arisen over this immense timespan in a one-hour lecture is really an impossible task but a necessary one to provide background to the appearance of man (next lecture) very late in this long sequence.
Please review the lecture outline and slides before class.
Lecture Outline
- Nature of the course
- History of life on Earth
- Before Earth formed
- Very early Earth
- Life begins
- The first few billion years
- Photosynthesis
- Ediacaran period
- The Cambrian explosion
- Paleozoic life
12. Mesozoic, Age of Reptiles
13. K/T extinction
14. Cenozoic, Age of Mammals
15. Primates and Man
Concepts introduced in the first lecture
- The extremely long time Earth has existed
- The extremely long time life on Earth has existed
- Life started very early in Earth history and has persisted, in great diversity, ever since
- For most of that time life only existed in small simple forms
- The evolution of complex animal life was a later event in Earth history
- The fossil record is very sparse before the advent of more complex animal life
- The forms of life on Earth changed with time as life continuously evolved
- Each segment of past time has a different characteristic assemblage of forms of life
- Man, and his immediate ancestors, are very late arrivals on the planet
Lecture 1 ends with with a list of conclusions.
- The Earth is very old and there has been life on Earth, in tremendous variety, for a very long time.
- Evolution, the changes in the forms of life with time, is a process that is slow, but is inevitable.
- Forms of life have continuously changed throughout Earth history, producing a bewildering variety of forms of life.
- The evolutionary process does not run to a plan. If there had been intelligent life, say back in the Mesozoic, it could not have predicted what life would be like in the Cenozoic. Evolutionary paths are not predictable. Evolution has followed different paths in geographically separate portions of the Earth.
- The sequence of forms of life throughout time is unique and does not harbor repetitions. As evidence of this, the fossil assemblage for any rock strata is a reliable indicator of the age of the strata.
- The rise of the mammals and our ancestry was made possible because a big rock hit the Earth 65 million years ago.
- Our species, Homo sapiens, is a newcomer, having been around for around 300,000 years, only the last 0.007 percent of the time the Earth has existed.
Lecture 2 will be on 'The Evolution of Man'