Climatic change in the advancement of early man
Answers
Fluctuation
Paleoanthropologists – scientists who study human evolution – have proposed a variety of ideas about how environmental conditions may have stimulated important developments in human origins. Diverse species have emerged over the course of human evolution, and a suite of adaptations have accumulated over time, including upright walking, the capacity to make tools, enlargement of the brain, prolonged maturation, the emergence of complex mental and social behavior, and dependence on technology to alter the surroundings.
The period of human evolution has coincided with environmental change, including cooling, drying, and wider climate fluctuations over time. How did environmental change shape the evolution of new adaptations, the origin and extinction of early hominin species, and the emergence of our species, Homo sapiens? (‘Hominin’ refers to any bipedal species closely related to humans – that is, on the human divide of the evolutionary tree since human and chimpanzee ancestors branched off from a common ancestor sometime between 6 and 8 million years ago.)
How do we know Earth’s climate has changed? How quickly and how much has climate changed? One important line of evidence is the record of oxygen isotopes through time. This record of δ18O, or oxygen stable isotopes, comes from measuring oxygen in the microscopic skeletons of foraminifera (forams, for short) that lived on the sea floor. This measure can be used as an indicator of changing temperature and glacial ice over time. There are two main trends: an overall decrease in temperature and a larger degree of climate fluctuation over time. The amount of variability in environmental conditions was greater in the later stages of human evolution than in the earlier stages.