How did humans learn about Toxicants?

Toxicants are not new. Early humans learned by a potentially fatal Russian roulette game of trial and error which plants were and were not food. This vital information was transmitted through the cultural food practices of the group.

Early groups recognized the alkaloids in plants for their religious, medical, and social opiate uses.
 These same alkaloids from plants are currently our drugs of abuse.

Some of the earliest nutritional studies pointed out that products used as food had toxic factors . Early studies on rats fed raw soybeans showed that the rats would fail to grow unless the soybeans were first cooked. Other legumes and egg white showed similar toxicities when fed raw. These toxic factors were subsequently shown to be enzyme inhibitors. Other types of molecules were found to have a variety of toxic effects.