ABSTRACT
Heterotrophs, animals differ from plants, algae, and related photosynthetic microbes—all autotrophs—in being unable to make food. This inability requires heterotrophs to seek it in the environment. When food is scarce, heterotrophs migrate to another area in hopes of finding new options. Heterotrophs target plants, animals, or both as food depending on their status as herbivores, carnivores, or omnivores. Although the first primates were likely specialists in targeting insects, many today are generalists in eating many foods. Humans typify the generalism inherent in omnivory, which is an outgrowth of their status as primates and a product of evolution. The lineage leading to humanity had many species, all but one now extinct. All sought to modify the environment in seeking food. This quest involved a range of strategies known as foraging, collecting, gathering, scavenging, hunting, and fishing. All primates, including species closely related to us, display some of these behaviors. Modern humans expanded these possibilities by inventing agriculture and animal husbandry, in the process of remaking the environment in striking ways to produce food. Rather than depend on their surroundings in a static way as do most animals, people manipulate their world through science and technology to yield food. Study and critique of farming and livestock raising demonstrates their potential to harm humanity and the world.
