Human Evolution Lecture Notes

Vocabulary flashcards covering human evolution, biological concepts, primate origins, and the archaeological record of hominins and early Homo species.

Macroevolution

Evolution above the species level; the focus of which is the formation of new species (speciation) and the evolutionary relationships among groups of species.

Speciation

The formation of new species.

Isolating mechanisms

Factors that separate breeding populations, preventing gene flow and creating divergent subspecies or species.

Cladogenesis

Speciation through a branching mechanism whereby an ancestral population gives rise to $2$ or more descendant populations.

Heterochrony

Change in the timing of developmental events that is often responsible for changes in the shape or size of a body part.

Neotany

A condition where juvenile traits are retained in the adult state.

Homeobox gene

A gene responsible for large-scale effects on growth and development frequently responsible for major reorganization of body plans.

Punctuated equilibria

A model of macroevolutionary change suggesting evolution occurs via long periods of stability (stasis) punctuated by periods of rapid change.

Anagenesis

A sustained directional shift in a population’s average characteristics where speciation occurs gradually without an evident break from the last species.

Derived characteristics

Characteristics that define a group of organisms that did not exist in ancestral populations.

Ancestral characteristics

Characteristics possessed by an organism or group of organisms due to shared ancestry.

Convergent evolution

A process by which unrelated populations develop similarities due to similar function rather than shared ancestry.

Continental drift

The movement of continents embedded in underlying plates on the earth's surface in relation to one another according to the theory of plate tectonics.

Adaptive radiation

Rapid diversification of an evolving population as it adapts to a variety of available niches.

Preadapted

Possessing characteristics that, by chance, are advantageous in future environmental conditions.

Homeotherms

Animals that maintain a relatively constant body temperature despite environmental fluctuations.

Isotherms

Animals whose body temperature rises or falls according to the temperature of the surrounding environment.

K-selected species

Species that use a reproduction strategy involving the production of relatively few offspring with high parental investment in each.

R-selected species

Species that use a reproduction strategy involving the production of large numbers of offspring with relatively low parental investment in each.

Arboreal hypothesis

A theory for primate evolution proposing that life in the trees was responsible for enhanced visual acuity and manual dexterity.

Visual predation hypothesis

A hypothesis by M. Cartmill proposing that hunting behavior in tree-dwelling primates was responsible for enhanced visual acuity and manual dexterity.

Aegyptopithecus

A monkey-like skull and body with ape-like Y5 molars, exhibiting high sexual dimorphism; no bigger than a modern house cat.

Proconsul

The first Miocene fossil ape remains found in Lake Victoria; characterized by Y5 molars, no tail, and broad flexible shoulder joints.

Molecular clock

The hypothesis that dates of divergences among related species can be calculated by examining genetic mutations accrued since the divergence.

Precipitation (Molecular)

When a dissolved substance is removed from a liquid form through chemical transformation to a solid form, used in comparing blood proteins.

Bipedalism

The mode of locomotion in which an organism walks on its two hind legs.

Australopithecus

A genus including several species of early bipeds from eastern, southern, and central Africa living between about $1.1$ and $4.3$ mya.

Hominins

A term used to refer specifically to humans and fossil bipeds.

Hominids

A term used to refer to humans and apes.

Foramen magnum

The opening at the base of the skull through which the spinal cord leaves; it is centered in bipeds and toward the back in knuckle-walkers.

Savannah

A semi-arid plains environment as found in eastern Africa.

Diastema

A space between the canines and other teeth allowing large projecting canines space within the jaw.

Gracile australopithecines

Members of the genus Australopithecus possessing a more lightly built chewing apparatus and likely a diet including more meat.

Robust australopithecines

Species within Australopithecus living from $2.5$ to $1.1$ mya known for a rugged chewing apparatus, including large back teeth and a sagittal crest.

Sagittal crest

A crest running from front to back on the top of the skull midline to provide surface bone for the attachment of large chewing muscles.

Law of competitive exclusion

The principle that when two closely related species compete for the same niche, one will out-compete the other, bringing about the latter's extinction.

Homo habilis

Meaning 'Handy Man'; the first fossil members of the genus Homo appearing $2.5$ mya with larger brains and smaller faces than australopithecines.

Percussion method

A stone tool manufacture technique performed by striking raw material with a hammerstone or against a stone anvil to remove flakes.

Lower Paleolithic

The first part of the Old Stone Age beginning with Oldowan tools spanning from about $2.6$ mya to $200,000$ or $250,000$ years ago.

Oldowan tool tradition

The first stone tool industry, beginning $2.5$ to $2.6$ mya and utilizing the percussion method.

Gender

The cultural elaboration and meanings assigned to the biological differentiation between the sexes.

Marrow

The tissue inside of long bones where blood cells are produced, containing concentrated protein and fat.

Tertiary scavenger

In a food chain, the third animal group (second to scavenge) to obtain meat from a kill made by a predator.

Acheulean Tool Tradition

The tool-making tradition of Homo erectus in which hand-axes were developed from the earlier Oldowan chopper.

Hand-axe

A tear-drop shaped tool pointed at one end with a sharp cutting edge all around.

Bipolar percussion

A tool-making technique involving holding a stone against an anvil and striking it with a hammerstone.

Culture

Learned, shared human behavior.

Broca's area

A front central area of the human brain that aids in language production.

Wernicke's area

A lower rear central area of the human brain that allows language comprehension.

Hypoglossal canal

The opening in the skull that accommodates the tongue-controlling hypoglossal nerve; in humans, it is twice the size of any ape's.

Levalloisian Technique

A tool-making technique by which $3$ or $4$ triangular flakes were detached from a specifically prepared core resembling a tortoise shell.

Hafting

The technique of attaching small stone bifaces and flakes to handles of wood to create knives and spears.

Neandertals

A distinct group within Homo inhabiting Europe and SW Asia from approximately $30,000$ to $125,000$ years ago, characterized by robust builds and occipital buns.

Occipital bun

A spot on the back of the head where large neck muscles attach, specifically noted in Neandertals.

Middle Paleolithic

The middle part of the Stone Age characterized by the Mousterian and Levalloisian traditions.

Mousterian tradition

The tool industry of Neandertals and their contemporaries from $40,000$ to $125,000$ years ago, featuring lighter and smaller tools than the Acheulean.

Hyoid bone

A bone associated with the muscles of speech in the larynx; its shape in Neandertals matches that of modern humans.

Lexigrams

Pictures on a computer screen used to teach communication and word association, as demonstrated with Kanzi the bonobo.