Origin of the Earth and the Geological Ages
The history of humans is closely related to the history of the earth. The earth contains geological, archaeological and biological records of historical times in its upper layers. They are important for reconstructing the history of the earth and various living organisms. The fossil bones of the human ancestors are embedded in the earth’s layers.
Palaeoanthropologists and archaeol-ogists excavate the soil and rock layers on the earth and extract evidence about hu-man ancestors. These layers and the fossils are scientifically dated to study the various stages in human evolution and prehistory. Through the gathered evidence, they at-tempt to understand the evolution of hu-man history and developments in a chron-ological order.
Archaeology is the study of human past through the analysis and interpretation of material remains.
Palaeoanthropology is the study of the human ancestors and their evolution by the study ofthe fossil remains.
The earth was formed approximately 4.54 billion years ago. Gradually, conditions emerged for the growth of organisms. Then plants and animals came into being, and thereby foundation was laid for the evolution of humans. The long span of time in earth’s history is divided into eras, periods and epochs by the geologists
The earliest trace of life in the form of microorganisms emerged 3.5 billion years ago. The primitive multi-cellular form of life first appeared in the Proterozoic era, about 600 to 542 million years ago. In the Palaeozoic era (542 to 251 million years ago), fish and reptiles along with various plants appeared. Dinosaurs existed in the Mesozoic Era (251 to 66 million years ago). Australopithecines (literally ‘southern ape’) appeared in the Cenozoic era, which commenced about 66 million years ago.
Australopithecines were the apes from which modern humans evolved. Now they are extinct, but they are considered to be the close relatives of humans.
1 billion = 100 crore
1 million = 10 lakh