Only a few hundred plants and a few dozen animals among all the species in the world were suitable for domestication, and nearly all of them were domesticated at least 5000 years ago. The Agricultural Revolution started in the Middle East because that region had the most plants and animals suitable for domestication. In this way, people were able to increase the percentage of the ecosystem’s biological production that was available for human consumption (see Figure 3.1B), and the carrying capacity for humans increased.įigure 3.1 - Distribution of biological production among plants and animals in the ecosystem food web They also domesticated some of the wild animals that they used as food. They eventually domesticated some of the plants by selecting individual species with desirable characteristics such as edible parts that were larger or easier to process for consumption. People encouraged wild plants that they used as food to grow near their dwellings, making food gathering easier. Agriculture in its simplest form first appeared about 12,000 years ago in the Middle East. This changed after the Agricultural Revolution, which enabled people to create their own small ecosystems for food production. Humans probably consumed about 0.1 per cent of the biological production in the ecosystems in which they lived. The carrying capacity for humans was similar to that of other animals, and human populations were no larger than the populations of other animals. With their hunting and gathering technology, humans were able to capture only a small part of the ecosystem’s total biological production as food for their own consumption. Humans lived in natural ecosystems that contained many different kinds of plants and animals, only some of them suitable as human food (Figure 3.1a). The physical and mental abilities of modern humans - and their ecological position in the ecosystem - were formed by several million years of evolution as hunters and gatherers. Human Population History From hunting and gathering to agriculture The chapter finishes with implications for the future. It describes the expansion of human population as the Agricultural Revolution spread around the globe, and the explosive increase in population that followed the Industrial Revolution. Why did the human population increase so rapidly during the past few centuries, after growing so little for such a long time? Have modern science and technology freed humans from population regulation and the limitations of carrying capacity that apply to other animals? This chapter provides an overview of human population history, starting with the small population of hunter-gatherers that constituted humanity for almost all of its history. The population has multiplied to six billion people during the 12 generations since 1700. By 1700 AD, there were about 600 million people around the world. About 10,000 years ago humans began to increase their numbers in a few parts of the world, an increase that continued gradually until 300 years ago. The entire human population of the planet was probably less than ten million people during nearly all of that time. Homo sapiens have existed for at least 60,000 generations. The first humans known to live in the Western Hemisphere migrated there from Asia about 13,000 years ago. Homo sapiens extended its population to Europe, Asia and Australia about 40,000 - 50,000 years ago. The modern human species (Homo sapiens) appeared in Africa about 1.3 million years ago and remained only in Africa for many years. Humans (Homo erectus) expanded their populations through Europe and Asia at least a million years ago. According to archaeological evidence, the first humans (Homo habilis) appeared in Africa about three million years ago.
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