Anthropology Study Guide 2: Evolutionary Theory, Classification, and Primatology

Vocabulary practice flashcards based on Anthropology Study Guide 2, covering speciation, macroevolutionary patterns, dating methods, mammalian taxonomy, primate adaptations, and comparative ape behavior.

Biological Species Concept

The concept defining a species as a group incapable of breeding with one another, because of reproductive isolation barriers (R.I.B).

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Prezygotic Barriers

Reproductive isolation barriers that take effect before sperm and egg come together.

Ethological / Behavioral Isolation

A prezygotic barrier where groups are pushed together due to outside factors or environments and hybrids form (fact check the hybrid part?), but behavioral differences keep the species distinct and won’t allow for reproduction (e.g., Hamadryas baboons and Anubis baboons).

F1 Inviability

A postzygotic barrier where first-generation hybrids can form a zygote that is incompatible with life, or survives with reduced fertility/infertility and cannot successfully reproduce.

F1 Sterility

A postzygotic barrier where hybrid offspring survive but are completely sterile and unable to reproduce because their parental genes are too different (e.g., horse + donkey = sterile mule).

Phylogenetic Species Concept

Also known as the morphological species concept; defines a species as a cluster of individual organisms that share a common ancestor and possess a unique combination of derived traits.

Anagenesis

Straight-line evolution where a single lineage transforms over time from Form A to Form B to Form C without branching.

Cladogenesis

Branching evolution where a single ancestral species with its own variation splits into several distinct branches that adapt to different environments and form new species.

Adaptive Radiation

The rapid diversification of a single ancestral species into a multitude of new forms to exploit different ecological niches and resources.

Gradualism

The model proposing that evolutionary change takes place continuously over vast, long time scales that are difficult for the human mind to imagine.

Punctuated Evolution

An evolutionary pattern characterized mostly by long periods of stasis (staying the same) interrupted by short, sudden, rapid environmental change events, such as volcanic eruptions.

Orthogenesis

A biological misconception proposing that evolution is directed toward a specific predetermined goal; in reality, evolution is not headed in any specific direction.

Relative Dating

A technique based on the Law of Superposition used to determine the chronological sequence of events and artifacts by establishing which is older or younger.

Chronometric Dating

A method used to determine the specific numerical age of an archaeological artifact or fossil.

Phylogeny

The study of evolutionary relationships and the branching lineage histories among organisms.

Homology (Homologous Traits)

Traits in two species that share similar underlying anatomical structures because they were inherited from a shared common ancestor, though they may or may not perform the same function.

Homoplasy (Analogous Traits)

Similar traits across different species that have a similar function but different anatomical structures, having evolved independently rather than from a common ancestor (e.g., bird wings and bat wings).

like two species derived from the same ancestor, that ancestor didnt have the trait, but the two species got it from diff outside pressures like environmental pressures

Parallel Evolution

A type of homoplasy where two species originating from the same ancestor diverge and independently acquire the same trait due to similar environmental pressures.

Convergent Evolution

A form of homoplasy where distantly related animals independently develop similar anatomical structures and functions in response to similar environmental factors.

Primitive Trait

An anatomical feature or character state that has not changed from the ancestral condition.

Derived Trait

An anatomical feature or character state that has changed or modified from the ancestral condition.

Cladistics

A classification methodology that counts only shared derived traits and homologous structures, explicitly ignoring shared primitive traits when constructing biological groupings.

Phenetics

A classification approach that groups organisms based on overall morphological similarities, counting both primitive and derived shared traits without distinguishing between homologous and convergent/parallel traits.

Phylum Chordata

A major taxonomic phylum characterized by the presence of a spinal cord and gill slits at some stage of embryonic development.

Subphylum Vertebrata

A subphylum characterized by bilateral symmetry and bones (vertebrae) enclosing and protecting the spinal cord.

Class Mammalia

A vertebrate class defined as warm-blooded and hairy organisms whose young are nourished on milk supplied by the mother's mammary glands.

Subclass Eutheria

Placental mammals that develop a placenta to nourish offspring internally and give birth to a relatively mature fetus.

Prototherians (Monotremes)

Primitive mammals that lay eggs rather than giving live birth; represented today solely by the platypus and two species of spiny anteater.

Metatherians (Marsupials)

Mammals that give birth to an extremely underdeveloped fetus and continue its development inside an external pouch (e.g., kangaroos and opossums).

Homeotherm

An organism that maintains a constant internal body temperature, permitting survival across diverse environments at the expense of high metabolic energy.

Heterodont

An organism possessing specialized teeth with different shapes and functions to process various foods, limited to two sets throughout life.

K-Selected

A reproductive strategy emphasizing offspring quality over quantity through high parental investment and care (e.g., humans).

r-Selected

A reproductive strategy emphasizing offspring quantity over quality, characterized by large numbers of offspring and relatively low parental care (e.g., frogs).

Cerebrum

The outer forebrain region associated with memory, learning, and intelligence; in mammals, it is larger and highly convoluted to accommodate more brain cells and neural connections.

Binocular Stereoscopic Vision

A visual system with overlapping visual fields where both hemispheres of the brain receive input from both eyes, producing precise depth perception.

Behavioral Flexibility

The capacity of an organism to modify learned behaviors in response to shifts in ecological, social, or demographic environments; fundamental to primate culture.

Solitary Group

The smallest primate social grouping, composed solely of an adult female and her dependent young.

Polygyny

A mating system where a single male maintains sexual bonds with multiple female partners simultaneously.

Polyandry

A rare mating system in primates where a single female maintains sexual bonds with multiple male partners concurrently.

Multimale / Multifemale Group

A social structure comprising multiple adult males, multiple adult females, and their offspring; the most widespread social arrangement among non-human primates.

Sexual Dimorphism

Measurable physical differences in size, coloration, or morphology between males and females of the same species (e.g., males being larger than females).

Prosimians

Primitive primates found primarily in Madagascar, Africa, and Asia (22 species) with smaller body and brain sizes, a heavy reliance on olfaction, nocturnal habits, and vertical clinging and leaping locomotion.

Tarsier

An unusual Indonesian prosimian with massive eyes, a dry nose, nocturnal and solitary habits, an owl-like appearance and behavior, and a diet of insects, arachnids, and small vertebrates.

Aye-Aye

A solitary, nocturnal lemur with an elongated middle finger used to extract wood-boring insects and larvae; exhibits convergent ecological traits with woodpeckers.

Ring-tailed Lemur

A diurnal, terrestrial prosimian characterized by female-dominant social groups, scent glands used for territorial marking, and male 'stink fights'.

Anthropoids

The 'higher primates,' encompassing monkeys, apes, and humans, marked by larger brain-to-body size ratios, fully enclosed bony eye sockets, diurnal rhythms (except the owl monkey), and complex social dynamics.

Platyrrhines (New World Monkeys)

Arboreal primates of superfamily Ceboidea that evolved ~30 million years ago, possessing flat noses with side-facing nostrils, four extra premolars, and prehensile tails in some taxa.

Catarrhines (Old World Monkeys)

Quadrupedal primates with downward-facing nostrils divided into Cercopithecines and Colobines, sharing dental formulas with humans and occupying diverse habitats from rainforests to snowy Japanese mountains.

Hominoids

The primate group encompassing humans and apes, defined by the absence of an external tail, large body sizes, high intelligence, K-selected life histories, and a Y-5 lower molar cusp pattern.

Y-5 Pattern

A distinct dental trait in hominoid lower molars featuring five cusps separated by grooves forming the letter 'Y', rather than the four-cusped bilophodont pattern of Old World monkeys.

Gibbons (Hylobates)

Small Southeast Asian apes (4 genera, 16 species) adapted to brachiation with extremely long arms, elongated fingers, reduced thumbs, monogamous pairings, and no sexual dimorphism.

Gorilla

The largest great ape (Eastern and Western species) exhibiting extreme sexual dimorphism, a uni-male (one-male, multifemale) social system, and a folivorous diet (~85% leaves) supported by specialized digestive tracts.

Orangutan Social Structure

A dispersed, solitary social organization driven by localized fruit shortages, where adult females range with infants and solitary adult males defend expansive territories without forming cohesive groups.

Bonobos (Pan paniscus)

A chimpanzee species south of the Congo River characterized by peaceful, egalitarian, female-bonded groups, strong mother-son ties, and frequent recreational sex for pleasure across a 40-day estrous cycle.

Common Chimpanzees (Pan troglodytes)

A chimpanzee species characterized by aggressive, male-dominated societies, male coalition alliances, territorial inter-group violence, and strictly reproductive sex during a 10-day estrous cycle.