Niche

Humans also have fundamental and realized niches. Like other species, the fundamental niche of humans is bounded by their biological tolerance of extremes of environmental conditions.

However, unlike other species humans have developed an extraordinary ability to utilize technology to mitigate extremes of environmental conditions, allowing survival in otherwise inhospitable places. In this sense, humans have utilized technological innovations to greatly expand the boundaries of their realized niche. Humans can now sustain themselves in Antarctica, on mountain tops, in the driest deserts, in phenomenal densities in cities, and even in spacecraft.

Humans have also expanded the dimensions of their realized niche by managing the intensity of their interactions with other species. Humans control their own competitors, predators, parasites, and diseases, thereby reducing the constraints that these biological stressors exert on the realized, human niche. Humans also manage the ecological constraints of their mutualistic plants and animals such as agricultural cows, pigs, chickens, and plant crops.

The phenomenal expansion of their realized niche has allowed a great increase in the abundance of humans. For most of their evolutionary history, humans engaged in a hunting and gathering lifestyle, and their global population was probably a few million individuals. The first significant expansions of the realized human niche involved the domestication of fire and the development of primitive tools and agricultural methods, all of which allowed populations to increase. During the past several centuries of extraordinary technological development, populations of humans have grown especially quickly, and in 1995 almost six billion people were alive on Earth. This growth has been accomplished through expansion of the realized niche of industrial humans.

However, it must be understood that the remarkable technological expansions of the realized niche of humans require large and continual subsidies of energy, food, and other resources. These are needed in order to maintain the colonization of difficult environments and to continue the control of constraining ecological influences. If access to these resources is somehow diminished, then the ability of humans to colonize and manage their environment is diminished as well, or it collapses.