Final answer:
The climate during the time of Sahelanthropus and Lucy was cooler than today, characterized by ice ages and rapid climatic changes. These conditions led to survival strategies like migration and development of new tools. The presence of megafauna alongside early humans further illustrates the era's environmental characteristics.
Step-by-step explanation:
The climate and environment during the time of the ancestors of Sahelanthropus (often mentioned as 'Salam') and Lucy (Australopithecus afarensis) can be reconstructed based on geological and fossil evidence. Lucy lived approximately 3.2 million years ago during the Pliocene epoch, when the Earth was cooler than today and experienced an ice age. Our planet encountered large, rapid changes in climate associated with the growth and retreat of continental ice sheets. These changes influenced the distribution and availability of resources, prompting early humans to form tight-knit, migratory communities.
During the late Quaternary, the climate was even more variable with frequent cold periods, and early humans, including Homo sapiens, adapted by developing new tools, learning to control fire, and eventually, migrating out of Africa as the climate there grew increasingly dry. These migrations were responses to the changing climate and resource distribution, which ultimately resulted in the global spread of human populations. The range of Pleistocene megafauna like mammoths, mastodons, and giant sloths provided evidence of the diversity of life forms that coincided with early humans and further affirms the environmental conditions of the time.
With the advent of agriculture around twelve thousand years ago, early human societies began to establish settled communities and alter their environment on a larger scale, leading to drastic ecological changes even before the development of modern industrial society. This historical environmental impact underscores the relationship between human evolution and climatic conditions throughout the ages.