The Social Biology of Ants

If a capsule statement were required defining the prime significance of ants as research objects, it could be the following: the ants are a world­ dominant taxon (family Formicidae) which have achieved their radiation by means of social modifications. They are unique in the magnitude of this achievement, being only remotely approached by their nearest competitors, the termites. With the ants, of which there are over ten thousand species, we are allowed to witness the employment of social design to solve the most diverse ecological problems ordinarily dealt with by single organisms. It is tempting to speculate (and perhaps impossible to prove) that these insects have employed all, or nearly all, of the social strategies permissible within the limits imposed by the hymenopteran brain and the peculiarities of their colonial system. In any case, the study of their social biology must still be considered in an early stage, notwithstanding an already large literature. In the present coverage, emphasis will be on the past fifteen years, al­ though there has been no hesitation to cite important earlier papers. For those interested, a historical perspective can be gotten by reading the books of Forel (53), Goetsch (58, 59), Richards (131), and Wheeler (185, 187). Only behavior and colonial organization are considered. Even after this restriction is made, certain topics have been omitted. Caste determination has been the subject of recent reviews by Brian (19) and Michener (1 15). Schneirla has summarized the results of his and his co-workers' welI-known studies on New World doryline army ants in several detailed articles (140, 142, 143, 148), which should be consulted in conjunction with two more recent research reports (144, 145) on the genus Neivamyrme:r. Especially useful are two of the reviews (142, 143) which take into account Raignier & Van Boven's treatise (128) on the African dorylines. Wilson (198) has considered early stages of army ant behavior in the primitive subfamily Ponerinae. In the present review, biological information in army ants has been mentioned where it was thought to have general significance. The special topic of fungus growing in the Attini has also been bypassed, in view of Weber's current publications (173, 174, 175), but other aspects of a.ttine biology are covered.