Thread of Life By: Roger Lewin This book covers the patterns of evolution and how each species and time era had an effect on Earth’s history. It covers the world from the beginning to the present times telling us all that has happened in between. The book begins by introducing us to geology and how it is used in telling time and finding fossils. The Grand Canyon is a good place to begin because it is the worlds greatest geological gash. Sediment was deposited here layer upon layer and eventually the layers were cut through by the Colorado River. The time covered by the layers of rock in the Grand Canyon represent about two billion years of earths history.
The next chapter introduces to us how life began. Many scientists believe that life began as soon as the earth cooled sufficiently after just forming. It is believed that the first life on earth emerged some four billion years ago. The author goes on to say that the beginning of life can be organized into five stages: first, the earth forms from materials in our solar system; second, chemicals such as sugars, phosphates, and amino acids are formed; third, these building blocks link together to form nucleic acids, proteins, carbohydrates, and fats; fourth, these turn into proto-organisms; and last, these organisms gain the ability to replicate. This explains how life begins. Soon the organisms of the water begin to evolve legs and lungs and start to venture out of the water onto the land.
This brings about the era of the dinosaurs. Dinosaurs ruled the earth for about 185 million years and then their populations began to decline. About 65 million years ago there is evidence that an asteroid struck the earth and caused the extinction of many species of marine plankton. The last of the dying dinosaur population may have died out before this. After the dinosaurs died off, then came the reign of the mammals. Mammals were more equipped for survival because of more intelligence and the development of a lower jaw comprised of one bone.
The Essay on Senior Year School Life Time
I dropped out of high school the last semester of my senior year. I was having a lot of problems at home and in my social life. I fell into the whole smoking pot stage, drinking all the time with my friends and ditching school. I was running with the wrong crowd and it was leading me into a dead end. I just sat around doing nothing but wasting my life away for four years. I had a few jobs in that ...
Upper and lower molars helped mammals survive better. Mammals would also stay with there young and nurture them until they were able to fend for themselves. Mammals were able to survive a very long time and are still evolving in present times. In the present, there is evidence that our human ancestors walked erect some 3. 75 million years ago. Facts suggest that we evolved from primates and our latest ancestor is the chimpanzee.
The human race turned out to be the smartest species yet. The skills of invention and problem solving came to be very useful to mankind. Humans also invented language which was also very useful because they could communicate with each other. The most complex thing that we will probably never be able to conquer totally is the human brain. I learned a lot through the course of reading this book. Many of my beliefs have been tested due to new facts that have been made more obvious to me.
One part of the book that was very interesting was when it explained that if many species of animals hadn’t evolved, they would not have been here on earth today. Also, I had always thought that the asteroid that struck the earth was what ended the rule of the dinosaurs when really they were probably all dead by then. I learned a lot about Darwin and what he studied and the theories that he came up with. In closing, this book was very good and very insightful. I would definitely recommend this book to anybody who is interested in the history of the earth. The book had very good illustrations and pictures to help you understand the message it is trying to convey..
