|Monkeys, Apes and Humans
Department of Anthropology, University of Missouri-Columbia
Glossary: Know these terms
"Selfish" gene theory: A model of evolution, a gene's eye view of natural selection. Genes are replicators, individuals are their vehicles. Replicators make copies of themselves. Successful replicators make more copies than unsuccessful replicators. Improved vehicles (bodies) promote their success.
Adaptive radiation: Occurs when a species diversifies into multiple niches. This diversification is speciation-one species becomes many. Classic example: the prosimians of Madagascar.
Agonistic buffer: Example, when a subordinate baboon feels threatened he grabs an infant. He becomes less vulnerable to attack. The infant is an agonistic buffer.
Allometric relation: If you compare a hundred species of primates you will find relations between body size and some traits. This relation is rarely 1: 1. For example, smaller species of primates need proportionally more calories than larger species-metabolism and body size is an allometric not a direct 1:1 relation.
Allomother: A female providing care to another female's infant. Allomothers may be practicing parenting skills, reciprocating or helping mothers, or may attempt to kidnap and harrn the infant.
Allopatric species: Species that live in different geographic areas. For example, common chimpanzees and bonobos are allopatric (cf Sympatric).
Altricial: Helpless, highly dependent, immature newborns (cf Precocial).
Altruism: A behavior that costs the doer and benefits others. Anthropology 60 Teaching Assistants are the only true altruists known to exist.
Analogous traits: Traits that two species have in common because of independent evolution in similar environment, not shared ancestry (cf. Homologous).
Arboreal: Living in trees. Gibbons are highly arboreal.
Australopithecines: Early (4.2-1.2 MYA) bipedal hominids. E.g., "Lucy" is a famous australopithecine fossil discovery. Several species.
Bipedalism: Walking upright on two feet. Humans are the only habitually bipedal primates.
Brachiation: Using arms to swing from tree limb to tree limb. Gibbons are brachiators extraordinaire.
Carrying capacity: The number of individuals an environment can support without degradation.
Cereopithecines: One of two major taxonomic subdivisions within Old World monkeys. Cercopithecines tend to have a more frugivorous and/or gramnivorous (seed eaters) diet than the other major taxonomic group, the Colobines, who are folivores (leaf eaters).
Coalitions: Groups of individuals within a primate troop usually cooperating to defend territory, acquire females, or challenge dominant individuals.
Colobines: One of two major taxonomic groups within Old World monkeys. Colobines have large guts and cellulose (enzyme) to digest leaves (cf. cercopithecines). They are Folivores.
Competitive exclusion: Two species cannot share a niche for long. One species will become ext nct or change to occupy a slightly different niche.
Concealed ovulation: No signs of ovulation (e.g., no estrus swellings). In humans, females are unaware when they are ovulating.
Conspecific: Individuals of the same species.
Darwin's Hostile Forces: The Big Problems individuals face in life. Features of the environment that cause differential survival and reproduction (i.e., natural selection). Climatic conditions, availability of food, availability of mates, and predators. For humans and maybe chimps a fifth Hostile Force may be important: inter-group competition with conspecifics.
Diurnal: Active during the day. Most humans are active during the day.
Dominance hierarchies: Primate societies usually have hierarchies-each adult member has a rank. Both males and females have dominance hierarchies. They vary in stability and linearity.
Estrus swellings: Swelling of the perineal region that occurs for a variable period around ovulation. Highly visible and may also involve pheromones.
Folivores: Species whose diet consists primarily of foliage. Folivores have large guts to extract the most energy from leaves. Examples: Red howlers, black and white colobus monkeys.
Frugivores: Species whose diet consists primarily of fruits. Examples: Chimpanzees, Gibbons.
Genotype: An individual's combination of genes. Note that genes do not directly determine your body or behavior. Phenotype is a result of the interaction of genotype and environment.
Group selection: A model of evolution. Some researchers believe that natural selection can favor traits benefiting groups to the disadvantage of individuals. Selection at the group level is expected to be weaker than selection at the individual level because groups do not reproduce as quickly as individuals and because group altruism can not resist the introduction of "selfish individuals." Do not confuse group selection with kin selection.
Hominid: A taxonomic group including modem humans and all ancestral species after the split with our closest relatives, the Chimpanzees.
Homologuous traits: Traits (characteristics) that two species share because of common ancestry (cf. Analogous).
Hypothesis: A proposition explaining a phenomenon such as the function of a behavior or the origin of a trait. Hypotheses should be falsifiable (i.e., testable). Hypotheses are derived from theory.
Individual selection: A model of evolution. Natural selection favors traits improving the survival and reproduction of individuals.
Infanticide: Killing an infant. E.g., among Hanuman langurs, infanticide typically occurs after male "takeovers."
Insectivores: Species whose diet consists primarily of insects. Example: the galago (bushbaby). The earliest primates were probably insectivores.
K-selection / r-selection: K-selected species reproduce slowly. They produce altricial offspring requiring a long time to maftire. R-selected species reproduce quickly and have many offspring. They produce many precocial offspring that quickly mature. K-selection and r-selection are relative terms. Prosimians are more r-selected than apes but ants are much more r-selected than prosimians.
Kin selection: A model of the evolution of cooperative behavior. Individuals help relatives because relatives share genes. By helping relatives to survive and reproduce, individuals are helping perpetuate copies of their genes. Do not confuse kin selection with group selection.
Mate choice: An individual selects a mate by physical or behavioral or territorial characteristics. In polygynous species, females tend to be more picky in choosing mates while males are less selective.
Mate-control polygyny: A form of polygyny where males coerce females into harems and/or guard them from other males.
Monogamy: Mating relationship between one male and one female. Male and female reproductive variance is approximately equal. Classic example in primates: gibbons. Monogamy is usually associated with high paternal care.
Multi-male societies: (cf. uni-male societies). Many adult males live in a primate troop. For example, chimps live in multi-male societies.
Natural selection: The directional process of evolutionary change. Some genes or allelles become more common over time because of beneficial effects that they have on survival and reproduction.
Niche: A species' particular habitat, the ecological opportunities they exploit. Includes diet, where they live, when they are active. Two species are not expected to share the same exact niche for long.
Nocturnal: Active during the night. Insectivores usually hunt insects at night facilitated by big eyes.
Phenotype: The product of the interaction between genotype and the environment. E.g., your body.
Philopatry: "Love of place." Almost all primate societies are female philopatric. Females stay with their natal group, males migrate.
Phylogeny: Species arranged on a family tree. Phylogeny describes how species are related. The goa of taxonomy is to classify species by their evolutionary relationships.
Polyandry: A mating system. A female has several male mates in this breeding system. Females have greater reproductive variance than males'. Polyandry is uncommon. No primate species is purely polyandrous. Some mating relationships in tamarins are polyandrous but most are monogamous. Mates provide extensive paternal care in polyandrous relationships.
Polygyny: A mating system. A male has several female mates. Male reproductive variance is greater than females'. Classic primate examples: baboons, gorillas, langurs.
Precocial: Offspring born relatively mature and independent (cf. altricial.)
Range: The total area of a land an individual or group uses (cf. territory.)
Reciprocity: Tit-for-tat favor exchange. You scratch my back and I'll scratch yours. An individual may do a favor for another (e.g., watch over her infant) and the recipient returns the favor at a later date. Reciprocity is facilitated by individual recognition and long-term memory.
Reproductive success: The simplest definition: the number of an individual's offspring surviving to maturation. Natural selection favors traits improving reproductive success.
Resource-defense polygyny: Mates attract multiple mates by guarding resources critical for female reproduction (e.g., fruit trees). Resource-defense polygyny is expected in areas where critical resources are unevenly distributed and clumped. (cf. mate defense polygyny)
Sexual dimorphisms: Traits (including behavior) that differ in size, shape, or some other characteristic between two sexes of a species. Examples: Baboon males have larger canines and body size than females. Human females have larger breasts and hips than males.
Sexual selection: A type of natural selection that acts differently on males and females of the same species. Traits involved in mate competition (e.g., canines, flashy peacock tail) are products of sexual selection.
Species: Taxonomic groups, usually defined by inability to interbreed and produce viable offspring. Species are reproductively isolated from each other. Genes in one species cannot combine with genes from another species and produce a successfully reproducing vehicle (individual).
Terrestrial: Living on the ground. Humans are terrestrial. (Chimps are semi-terrestrial.)
Territory: The area defended (outgroup conspecifics are excluded) by an individual or group is her/their territory (cf. range, core area).
Uni-male societies: "Harem" societies. Composed of one dominant mate, several females, and their juvenile and infant offspring. E.g., Hanuman Langurs, Gorillas. Also referred to as "One-Male- Units" (OMUs).
Vertical leaping and clinging: Arboreal locomotion that involves jumping among vertical tree limbs and branches (as compared to running along the tops of branches). Tarsiers are a good example.
Department of Anthropology
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revised: fall 2004
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