Multilevel Societies Flashcards
What are multilevel societies (MLS)
Most complex social systems that have multiple distinct social levels, where social levels are nested within each other - each level includes the one above it
Describe humans in multilevel societies
Humans belong to different social groups and transition in/out depending on different circumstances
Which primates have multilevel societies (5)?
1) Asian colobines such as a) snub-nosed monkey, b) douc langurs, c) proboscis monkey
2) Cercopithecines such as a) geladas and b) hamadryas baboons
How is the structure of MLS defined?
1) At least 2 stable and consistent levels that separate the individual from the population (core unit, upper level)
2) The number of social levels and names given to levels differs among species
3) Social levels get larger and less socially cohesive moving down levels
What is the core unit in non-human primates usually?
OMU
What is the upper level in non-human primates usually?
Bands
What does the gelada MLS look like?
1) Core = unit (OMU or AMU)
2) Intermediate = team
3) Upper = band/ecological unit (sleep and forage together)
4) Apex = community (associations occur over the span of years)
What does the hamadryas baboon MLS look like?
1) Core = OMU
2) Intermediate = clan (OMUs + some solitary males)
3) Upper = band
4) Apex = troop
What does snub-nosed monkey MLS look like?
1) Core = OMU
2) No intermediate
3) Upper = band
4) Apex = troop
What does hunter-gatherer human MLS look like?
1) Core = family
2) Intermediate = extended family
3) Upper = band
4) Apex = community tribe
What are core units?
1) Highly cohesive/stable
2) Stay in regular/permanent proximity (spatially and socially)
3) Usually OMUs
What makes the OMUs of hamadryas baboons so special?
Hamadryas baboons have OMUs but also have follower males in the group (do not sire offspring)
What are intermediate levels?
1) Closely associated core units
2) Clans/teams
3) Interact with units in the same clan than units outside of clan
What are upper levels?
1) Consist of core units (and intermediate levels)
2) Must be stable enough to be recognized (i.e., recurring groupings that can be observed regularly)
3) Membership can be consistent or probabilistic (come together or separate based on circumstances)
What are apex levels?
1) Temporary aggregation of upper levels (typically at sleeping or foraging sites)
2) Distinctively large
How do we quantify social levels?
By calculating the association time (Snyder-Mackler)
1) Core units spend 100% of time together
2) Teams >90%
3) Bands >50%
4) Community <50%
What is fission-fusion?
Cleaving and coalescing to form subunits in response to socioecological factors (food, predation, mating)
What does fission-fusion look like in MSL?
Cleaving and coalescing into different social levels, but individual within levels remain the same
What are the adaptive functions of MLS?
Helps balance costs and benefits of group living, where different functions can be optimized at different social levels
What are some examples of adaptive functions in MLS of hamadryas baboons?
1) OMU = reproductive partners
2) Clan = maintenance of male-male relationships
3) Band = predator protection and resource defense
4) Troop = predator protection at sleeping cliffs
What are some general examples of adaptive functions of MLS?
1) Clans can split into individual units when food availability is low
2) Units can come together as a clan in the presence of predator/bachelor threats
How did multilevel societies come to be for geladas and hamadryas baboons?
1) Originally large multi-male/multi-female groups
2) Large groups sizes were due to localized resources
3) High aggression and harassment by unfamiliar individuals resulted in splitting into OMUs (for male reproduction and female protection)
How did multilevel societies come to be for snub-nosed monkeys?
Independent OMUs emerged due to persistent threat of infanticide from bachelor males
What is the social structure of gelada core units?
1) Shaped by kin bonds among females (female-female bond)
2) OMU or AMU
What is the social structure of hamadryas baboons core units?
1) Pair bonds between leader male and his females (male-female bonds)
2) OMUs
What is the unifying force that links social levels together?
Kinship
Describe kinship among hamadryas baboon females
1) Female dispersal is limited to bands
2) Females are more closely related maternally within OMUs
3) Leader and follower males are closely related maternally
4) Kin selection among females likely an organizing principle of MLS
What are some consequences of MLS?
1) Reproductive units and bachelor males live closely
2) High intrasexual selection (high density of competitors) = evolution of signals of male quality
3) Males have more developed sexually dimorphic traits
4) Asian colobines exhibit greater sexual dimorphism in body size
What does sexual dimorphism look like in MLS vs multi-male/uni-female and monogamous societies?
Sexual dimorphism is more pronounced in MLS compared to other societies
What is an example of monogamous monkeys that exhibit low sexual dimorphism?
Titi monkeys
