Making Sense of 7 Billion People
According to a back-of-the-envelope calculation, there are about 1.7 million other top-level, land-dwelling, mammalian predators on Earth. Put another way: For every non-human mammal sharing our niche, there are more than 4,000 of us.
In short, humans are Earth’s great omnivore, and our omnivorous nature can only be understood at global scales. Scientists estimate that 83 percent of the terrestrial biosphere is under direct human influence. Crops cover some 12 percent of Earth’s land surface, and account for more than one-third of terrestrial biomass. One-third of all available fresh water is diverted to human use.