Animal echolocation in the external ear. There are two hypotheses about the evolution of echolocation in bats. The first suggests that laryngeal echolocation evolved twice in Chiroptera, once in the Yangochiroptera and once in the horseshoe bats (Rhinolophidae). The second proposes that laryngeal echolocation had a single origin in Chiroptera, was subsequently lost in the family Pteropodidae (all megabats), and later evolved as a system of tongue-clicking in the genus "Rousettus". Individual bat species echolocate within specific frequency ranges that suit their environment and prey types. This has sometimes been used by researchers to identify bats flying in an area simply by
Microbial food cultures under the Food, Drug and Cosmetic Act. Section 409 of the 1958 Food Additives Amendment of the Food, Drug and Cosmetic Act, exempts from the definition of food additives substances generally recognized by experts as safe (GRAS) under conditions of their intended use. These substances do not require premarket approval by the US Food and Drug Administration. Because there are various ways to obtain GRAS status for microbial food cultures, there is no exhaustive list of microbial food cultures having GRAS status in the US. Within the European Union, microbial food cultures are regarded as food ingredients and are regulated