Intelligence has evolved many times independently among vertebrates. Primates, elephants and cetaceans are assumed to be more intelligent than 'lower' mammals, the great apes and humans more than monkeys, and humans more than the great apes. Brain properties assumed to be relevant for intelligence are the (absolute or relative) size of the brain, cortex, prefrontal cortex and degree of encephalization.
African elephants are conventionally classified as a single species: Loxodonta africana (Blumenbach 1797). However, the discovery in 1900 of a smaller form of the African elephant, spread throughout the equatorial belt of this land, has given rise to a debate over the relevance of a second species of elephant in Africa. The twentieth century has not provided any definite answer to this question.
From 1997 to 2000, six cases of Mycobacterium tuberculosis (TB) infection were diagnosed in three species of animals at, or recently originating from, the Los Angeles Zoo. Restriction fragment length polymorphism (RFLP) analysis showed that five of six animal isolates shared an identical IS6110 pattern, with the sixth differing only by one additional band. A multiinstitutional epidemiologic investigation was conducted to identify and interrupt possible transmission among the animal cases, and to screen personnel for active TB infection and TB skin-test conversion.
Toughening mechanisms based on the presence of collagen fibrils have long been proposed for mineralized biological tissues like bone and dentin; however, no direct evidence for their precise role has ever been provided. Furthermore, although the anisotropy of mechanical properties of dentin with respect to orientation has been suggested in the literature, accurate measurements to support the effect of orientation on the fracture toughness of dentin are not available.
(1) A captive herd of Asian elephants (Elephas maximus) exhibited dusting behaviour when the maximum daily temperature exceeded approximately 13°C, and dusting frequency increased directly with the environmental temperature. (2) Individual animals showed variation in dusting frequency but this was not related to body mass, suggesting that the function of dusting is not primarily thermoregulatory. (3) Synchronisation in the timing of dusting behaviour within the herd suggests that it may have a function in the maintenance of social cohesion.