A social learning model of conflict and cooperation in human societies

Patterns of conflict and cooperation both within and between societies may be related to the degree of cultural similarity within and between the same societies. A simple model of social learning is used to predict patterns of conflict and cooperation in hypothetical societies that differ in the roles of relatives and nonrelatives in the enculturation of children. The model is illustrated by comparing its predictions to known differences in the patterns of conflict between males inpatrilocal and matrilocal societies.     

Ability of predatory native Australian fishes to learn to avoid toxic larvae of the introduced toad Bufo marinus

Of two native Australian fishes naïve to the introduced toad Bufo marinus most barramundi Lates calcarifer rapidly learned to avoid B. marinus tadpoles, while sooty grunter Hephaestus fuliginosus exhibited considerable intraspecific variation in their learning ability. Some sooty grunter learned to avoid tadpoles after only a few attacks, while other individuals continued to attack and reject tadpoles throughout the entire laboratory trials. Individuals of both species recognized and avoided tadpoles 1 day after their previous encounter. None of the fishes died during the trials. The observed variation in behavioural responses of fishes to B. marinus may be due to differences in (1) learning ability, (2) fish hunger levels, and or (3) tadpole palatability and toxicity. The results demonstrate that most barramundi and sooty grunter learn to avoid B. marinus tadpoles with minimal trauma. Consequently, it is anticipated that the toads are unlikely to have a significant negative impact on wild populations of these fishes through direct toxic effects.     

Foraging Efficacy of a Larval Parasitoid in a Cotton Patch: Influence of Chemical Cues and Learning

Plant-herbivore chemical signals and behavioral plasticity may enhance parasitoid host-foraging efficacy in the field; however, no studies have quantified the potential benefits from these factors under field-type conditions. The effect of plant-herbivore signals and learning on the foraging efficacy of Microplitis croceipes was quantified by directly observing and recording total and sequential duration of various foraging behaviors relative to 5 randomly placed herbivore-damaged and host-infested cotton plants and 20 undamaged and non-host-infested plants. Microplitis croceipes spent significantly more time searching (flying and antennation) on host infested versus uninfested plants. Antennation time was significantly and negatively correlated with successive host stings. Contrary to expectations of increased duration, flight time remained constant throughout the foraging bout, which may indicate that there was some learning associated with flight. These results suggest that plant-herbivore chemical signals and learning enhances the foraging efficacy of M. croceipes.     

The role of ``conservatism' in herring migrations

Herring (Clupea harengus) migrationstend to remain constant over periods of severalyears or even decades, despite environmentalvariation. When a migration pattern is changed,apparently in response to an environmentalstimulus, the change in migratory behaviorsometimes lasts longer than the environmentalstimulus itself. This paper reviews evidencethat the response of herring to environmentalchange is restrained by conservatism. Herringapparently develop certain migratory habitsduring the early stage of adult life and tendto adhere to these habits for life, even whenthe environment changes. Two elements ofconservatism are distinguished: the formationof habits within one generation, and thetransfer of habits between generations. Anumber of case studies on North Sea herring andNorwegian spring spawning herring are reviewedin order to find evidence for habit formationand tradition in the migrations of thesepopulations. By eliminating the possibilitythat homing to spawning, wintering and feedinggrounds is due to innate behavior orenvironmental constraints, it is shown that thereturn of these fish to the same areas eachyear is most likely a form of learned behavior.In many cases, new year-classes adopt the samemigration pattern as their predecessors, whichis explained by the social transfer of habitsfrom old herring to young ones. A change ofmigration pattern is usually initiated by arecruiting year-class that lacks the ``guidance'of older herring at the time it has to startits first migration. This may be the effect ofa special environmental condition that affectsthe distribution of the recruiting age groupmore than that of the adult stock component, andthereby results in a separation of the twostock components. After the recruitingyear-class has adopted the new migration route,it tends to repeat it in subsequent years. Thenew migration thus becomes habitual. Subsequentgenerations may copy the migration and continuethis behavior even after the originalenvironmental cause has disappeared.