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Athena Review, Vol.4, no.1

Glossary of terms related to research on Homo erectus

(anatomy, archaeology, ecology, genetics, geochronology, geology, paleoanthropology)

Acheulean industry: Paleolithic stone tool industry characterized by the manufacture of bifacial handaxes, also called Mode 2 technology. Named for the site of Saint Acheul in northern France.

adaptive radiation: Rapid increase in related species on entering a new environment lacking competitors.

agenesis: Failure of a biological structure to develop.

air-fall volcanic ash: Ash from volcanic eruptions, which form tuff layers in the sedimentary sequence.

alcelaphine bovid: Member of the Tribe Alcelaphini of the Bovidae family, which includes the modern species of hartebeests and wildebeests. They are grazers in arid open-country.

Allen’s Rule: The observed tendency of mammals living in cold regions to have shorter extremities than members of the same species living in warm regions (after Joel Asaph Allen 1877).

allopatry: Dispersal and isolation of populations in separate, widely differing geographic regions.

alveole/alveolus: Tooth-bearing portion of the jaws.

anagenesis: Process of speciation in which a species evolves through time into a new species (contrast to cladogenesis).

anastomosis: Connection between parts of a branching system, as in veins of a leaf or streams in a river drainage. .

anterior fovea: Depression in forward part of tooth.

Anthropoidea: Superfamily of higher primates (New World Monkeys, Old World Monkeys, apes, and humans and their bipedal ancestors).

Aullan sea regression: A series of highly eroded sediments in northwest Tuscany (Italy) indicate a cold, rainy climate associated with an abrupt glacially-induced drop in sea level. The Aullan sea regression coincides with the end of the Olduvai paleomagnetic episode, about 1.8 million years ago. Cold-adapted mammalian fossils are found in Aullan deposits.

autapomorphy: New morphological trait unique to a group in an evolutionary lineage; uniquely derived feature (see also cladistics).

autosome: Any chromosome except a sex chromosome.

basicranium: Part of the occipital bone at the bottom of the skull.

bauplan: A fundamental or generalized “body plan” or body structure for a major taxon or group of organisms. From the German for “building plan” or “blueprint.”

biorbital breadth: Distance from outer orbit (eye socket) to outer orbit at widest point.

bizygomatic breadth: Distance from cheekbone to cheekbone at widest point.

Brunhes Chron: Paleomagnetic dating period of normal polarity, lasting from ca. 790,000 BP through the present.

buccal: Relating to the cheek.

calotte: Uppermost portion of the braincase; "skullcap" (equivalent to calva).

canine fossa: A depression above the canine tooth on the cheek of modern humans resulting from the reduction in the size of the face.

character displacement: Increased differences between species where they occur together, either morphological, behavioral, and/or physical.

character release: Increase in phenotypes within a species, due to lack of competition; opposite of character displacement.

clade: Branch (Gk.) or lineage which has split off from an ancestral group, as defined by advanced or derived traits.

cladistics: Method of biological systematics which seeks to determine evolutionary relationships (phylogenies) by interpreting patterns of primitive vs.derived (advanced) characteristics in morphology. Developed in the 1940s-60s by the German biologist W. Hennig; influential in paleoanthropology since the 1970s. A source of the Homo ergaster taxon.

cladogenesis: Form of speciation in which one species evolves via adaptive radiation or isolation into two or more descendant species, separated on the basis of derived traits (contrast to anagenesis).

clast: An individual constituent, grain, or fragment of a detrital sediment or sedimentary rock, produced by physical disintegration of a larger rock mass.

cline: Gradation of frequency of a population’s biological traits over geographical distances.

Continuity Theory: Specific theory that modern humans descended from a mixture of different Homo populations since initial migrations from Africa by 1.8 mya (also called Regional Continuity or Multiregional Theory). Related to general theory that species evolve gradually through natural selection, with corollary that interbreeding populations may exhibit considerable variation in morphology (see also Evolutionary Synthesis; contrast to Replacement Theory).

coronally oriented infraorbital surface: The surface of the face below the eye orbits on a flat plane horizontal to the midline of the skull.

cranial frontal angulation: Slope of the forehead.

cranial vault: Combination of skull bones that encase the brain.

cultural hitchhiking: Co-evolution of culture and genes; reduction in genetic diversity when neutral or nearly-neutral genes (such as mtDNA) and selectively advantageous cultural traits are transmitted in parallel.

cusps: Pointed or rounded bumps on the occlusal or chewing surface of a tooth.

deme: A population, or cluster of individuals, with a high probability of mating with each other compared with their probability of mating with a member of some other population, and therefore having a substantial amount of genetic exchange.

denticulate retouch: Tooth-like serrations on stone tool edges made by removal of small flakes, often by pressure-flaking with bone or soft hammer methods.

derived or advanced traits: Morphological traits which only appear in some members of the group, who comprise a separate clade, or branch (see also cladistics).

disturbed environment: Fragmented natural habitat affected by major changes in the physical environment such as climate, volcanism, or flooding.

East African Rift Valley: Long, narrow valley in Ethiopia, Kenya, and Tanzania caused by the separation of the Nubian, Somalian, and Arabian tectonic plates.

ecological release: Niche expansion under reduced interspecific competition, believed by some to be accompanied by increased morphological/phenotypic variability.

ecotone: Localized "edged community" between two other reasonably distinct communities; typically rich in species because they contain representatives from both parent communities and may also contain their own distinct species.

ectomorphy: Adaptive exaggerated linear build, associated in modern humans with dry, parching heat, which allows effective dissipation of heat through a high ratio of skin surface to body mass.

electron spin resonance (ESR) dating: Dating method that measures the concentration of electron traps in a material, which accumulate through natural radiation; method yields a minimum, rather than actual, age. ESR is the only absolute dating method which can be applied beyond 500,000 BP in a carbonated and karstic environment.

encephalization: Increase in brain size.

epiphysis: Part of a bone that is separated from the main body of the bone by a layer of cartilage and that subsequently unites with the bone through further ossification.

Evolutionary Synthesis: Evolutionary theory combining the Darwinian concept of natural selection with Mendelian genetics. Evolution is defined as the production of variation through genetic inheritance, and the sorting of variants by natural selection (Mayr 1963). Developed by biologists in the 1930s-50s (i.e., E. Mayr, T. Dobzhansky, GG. Simpson); influential in paleoanthropology since the 1940s. A source of the Homo erectus taxon.

exogenous: Originating from outside the organism or system.

first order behaviors: Behaviors immediately retrievable from the archaeological record (cf. Binford 1984).

foramen magnum: Large hole in the base of the skull where the spinal cord attaches to the skull.

frontal bone: Skull bone making up the forehead and upper portion of the eye sockets.

gene flow: The movement of genes into or through a population by interbreeding, or migration and interbreeding, with another population.

geochronology: Study of time in relationship to the history of the earth, especially by the absolute age and relative dating systems developed for this purpose.

grade: A level of organization based on the presence of common biological features and used in assessing diffferent evolutionary lines of animals.

half-life: Time period in which half the initial amount of atoms of a radioactive element disintegrates into non-radioactive atoms.

haplotype: Combination of genetic markers or polymorphisms in a gene or genome, such as the mtDNA, that are inherited together as a unit.

high-resolution mass spectrometry: Determination, usually by electrical means, of molecular weights and relative abundances of isotopes within a compound.

Himalayan fore slope: Essentially, the southern foothills of the Himalayan Mountains in current northeast Pakistan and north-central India. The fore slope has thick deposits of stream wash relating to the last burst of Himalayan uplift, 10-2 million years ago.

hippotragine bovid: Member of the Tribe Hippotragini of the Bovidae family, which includes modern horse-like antelopes such as oryxes. They are grazers in arid open country.

Hominidae/hominid: (Formerly:) family of humans and their bipedal ancestors; (now:) family of Paninae (chimpanzees and gorillas), and humans and their bipedal ancestors.

Homininae/Hominin: Sub-family of humans and their bipedal ancestors.

Hominoidea/hominoid: Superfamily of apes (chimpanzees, gorillas, orangutans, gibbons), and humans and their bipedal ancestors.

hornblende: Most common mineral of the amphibole group, occurring in many igneous and metamorphic rocks, typically black in color, but having variable composition.

hyoid: A horseshoe-shaped bone suspended from the base of the skull and forming part of the system of ligaments and muscles that control tongue movement.

hypoconulid: A flat accessory cusp, one of several cusps on a lower tooth.

hypodigm: All of the available information (e.g., fossils) about a taxon.

imbrication zones: Areas where tectonic plates meet, with one overlapping the other, as with shingles or tiles on a roof.

inert gaseous element: Non-reactive element in the gas state; noble gas.

Jaramillo Normal Subchron: Short shift in polarity during the Matuyama Chron, dated at 1.1-1.0 mya.

Kabuh (Bapang) Formation: Upper series of hominid-bearing strata in the Sangiran Dome in Java, producing Ar/Ar dates of 1.5 - 1.0 mya.

K-selection: The density-dependent selective force on organisms in a stable environment characterized by high competition, who produce few offspring of large size, with more energy expediture on each offspring and a high level of efficiency, relative to r-selection.

lithics: Collective term for stone tool artifacts and their raw materials, typically derived from river cobbles and rock outcrops. See also Mode 1 and Mode 2 industries.

malar incisure: Notch on the cheekbone (malar is equivalent to zygomatic).

mandible: Bone of the lower jaw.

mastoid process: A triangular bone behind the earhole on a human skull; usually more pronounced in males than females.

Matuyama Chron: Paleomagnetic dating period of reversed polarity, lasting from ca. 2.1 - 0.79 mya.

maxilla: Bones of the upper jaw.

metaconid: One of several major cusps on a lower tooth.

microtine rodents: Voles, lemmings and related small rodents used in biostratigraphy to help date the earliest human colonization of Europe (i.e. Arvicola, the modern water vole, first appears ca. 600,000 BP).

microwear analysis: Microscopic study of edge and side wear on stone tools, to determine artifact functions, amount of use, and subsistence-related flora and fauna.

mitochondrial DNA (mtDNA): DNA in the mitochondria of cells, rather than in the nuclei. Because mitochondria occur outside the nucleus of the cell, mtDNA is typically only passed on through the female, and hence reveals matrilineal relationships. Rate change for mtDNA is much faster than DNA of the nucleus, making it suitable for analyses of recent evolutionary developments.

Mode 1 technology: Earliest lithic phase of the Old World Lower Paleolithic, characterized by utilized flakes and core chopper tools, also called Oldowan industry.

Mode 2 technology: Second major lithic phase of the Old World Lower Paleolithic, characterized by bifacially flaked tools including handaxes; also called Acheulean industry.

morphology: Study of the various forms of the physiology or skeletal parts of organisms.

Movius Line: Postulated boundary of Acheulean handaxe manufacture at the western edge of the tropical evergreen forest in eastern India, first proposed by H.L. Movius (1949). This separated the handaxe-producing hominids of Africa, Europe, and western Eurasia from hominids in east Asia, not known to produce handaxes.

mylohyoid groove: Longitudinally running groove on the internal surface of the mandible (lower jaw), where the mylohyoid muscle (flat, triangular muscle forming the floor of the mouth) attaches.

non-coding: DNA sequence not involved in coding for a protein end-product.

non-recombining: Those portions of the human genome that do not combine, including mtDNA and the Y-chromosome. Because they are non-recombining, the mutations that occur in these segments of DNA are not reshuffled or mixed into new combinations, and hence, accumulate in a linear or chronological fashion.

nuchal plane: Area on rear of skull providing attachment for neck muscles.

nuchal torus: Ridge where neck muscles attach to the back of the skull.

nuclear genome: Full set of chromosomes, and corresponding inheritable traits, from the nucleus of a cell.

obligate biped: Upright walking hominid, whose anatomy dictates bipedality as primary means of locomotion.

occipital plane: rounded cranial area on rear of skull above nuchal plane.

occipital squamous portion: Large flattened portion of the occipital (rear) bone of the skull, separated from the small thick basilar portion by the foramen magnum.

occlusal wear: Wear on the chewing surface of a tooth.

Oldowan industry: Lower Paleolithic stone tool industry characterized by utilized flake tools and core tools; also called Mode I technology. Named for sites in the Olduvai Gorge in Tanzania.

Olduvai Normal Subchron: Short shift in polarity during the Matuyama Chron, dated at 1.99-1.77 mya Plio-Pleistocene transition). During this period, when the first long-distance Homo erectus migrations occurred, the Tethys corridor was extremely unstable (Larick et al. 2001; 2004).

orthognathic: Straight-jawed; without forward projection of the upper or lower jaw (contrast prognathic).

paleomagnetism: Dating method based on the periodic reversals of the earth’s magnetic polarity, often employed in dating of early hominine sites.

Paninae: Subfamily of chimpanzees (Pan troglodytes and Pan paniscus) and gorillas (Gorilla gorilla)(see also Hominidae).

Panthera: Genus of chiefly large cats, including extinct (Pleistocene) and modern species of lion, tiger, leopard, and jaguar.

parapatry: Restricted gene flow between the ancestral population and adjacent populations. (Milliken)

parietals: Right and left side bones at the top of the skull; joined by the sagittal suture.

patch: Portion of an ecological mosaic in a discontinuous or heterogeneous environment, which is distinguished by particular resources and typically exploited by an organism as a specialty niche.

penecontemporaneous: Formed at almost the same time; also said of a structure or mineral that was formed immediately after deposition of a sediment but before its consolidation into rock.

petrography: Branch of geology dealing with the description and systematic classification of rocks, especially igneous and metamorphic rocks, and especially by microscopic examination of thin sections.

phenocryst: One of the relatively large and ordinarily conspicuous crystals of an igneous rock.

phenotype: The observable, measurable, or testable characteristic of an organism for a particular trait (contrast to genotype).

Phyletic Gradualism: View of evolution as gradual, with small changes due to natural selection eventually leading to speciation. Thus gaps in the hominid fossil record, if filled, would tend to show a phyletic continuum between related taxa (see also anagenesis and Evolutionary Synthesis; contrast to Punctuated Equilibrium).

phylogeny: The study of evolutionary development of a species, often expressed with a family tree or branching diagram such as a cladogram

phytolith: Microscopic crystal secretion of a living plant that is often unique within a family, genus, or species.

plagioclase: Class of common rock-forming minerals within the group of feldspars, including albite, oligoclase, andesine, labradorite, bytownite, and anorthite.

plesiomorphy: Trait retained from an ancestral group or clade (see also cladistics).

Plio-Pleistocene: Time period around two million years ago, spanning the end of the Pliocene period of the Tertiary era and the following Pleistocene period of the Quaternary.

polymorphism: Genetic variability for a trait.

polytypic: Comprising several subspecies or geographical variants.

population: interbreeding localized group.

population bottleneck: Reduction in population size that may cause changes in gene frequency within a population.

postcranial bone: Bone from any part of the body except the skull and face.

pot lid fracture: Round fractures on the surface of a stone or stone tool caused by small flakes popping off when thermally treated.

primitive characters: Attributes retained from an ancestral group or clade (see also cladistics).

prognathism: Forward projection of the face; i.e., alveolar prognathism.

protoconid: The most buccal (i.e., nearest the cheek) of several major cusps on a lower tooth.

proto-prismatic cores: Stone cores prepared to produce an elongated flake when struck; predating Upper Paleolithic prismatic cores from which blades were struck.

Pucangan (Sangiran) Formation: Earliest level of hominid-bearing strata in the Sangiran Dome in Java, producing argon/argon dates of 1.81 and 1.66 mya.

pumice: A light-colored, cellular, glassy volcanic rock, often sufficiently buoyant to float on water. al.)

Punctuated Equilibrium: Evolutionary theory of long periods of equilibrium (stasis) interrupted by rapid episodes or bursts of speciation (Eldredge and Gould 1972). Includes assumption that many gaps in the fossil record are themselves real, and reflect relatively sudden replacement of one species by another due to migration or catastrophic events (see also Replacement Theory; contrast to Phyletic Gradualism).

radioactive isotope: One of two or more species of the same chemical element (having the same number of protons in the nucleus, but differing in the number of neutrons) capable of changing spontaneously into another element by the emission of charged particles from its nucleus.

radiometric dating: Calculation of an age in years for geologic or biologic materials by measuring the presence of a short-life radioactive element (e.g. carbon-14) or a long-life radioactive element plus its decay product (e.g. potassium-40 and argon-40). The term applies to all methods of age determination based on nuclear decay of naturally occurring radioactive isotopes.

Rapoport’s Rule: The observed tendency for species living in temperate or high-latitude environments to have broader latitudinal ranges than species living in tropical climates.

reduncine bovid: Member of the Tribe Reduncini of the Bovidae family, which includes the modern species of waterbuck and reedbuck. They are grazers in well-watered areas.

refitting: The recombining by archaeologists of stone cores with the flakes originally struck off them during lithic tool manufacture.

Replacement Theory: Specific theory based on mtDNA evidence that all modern humans are descended from an African population, who replaced all other Homo populations after 200,000 BP. Related to general theory that speciation results from adaptive radiation and cladogenesis, frequently with rapid replacement of one species by another (see also Punctuated Equilibrium; contrast to anagenesis).

routed foraging: Foraging behavior seen in chimpanzees. There is no evidence of planned resource exploitation.

r-selection: Density independent selective force on organisms in an unstable environment characterized by low competition, who produce many small offspring, with less energy expediture per offspring, relative to K-selection.

sagittal midline: Imaginary plane that transects the body along the mid-point into mirrored left and right sides.

second-order behaviors: Behavior that needs additional lines of evidence before it can be inferred from the archaeological record (cf. Binford 1984).

sensu lato: (Lat.) in the widest sense of the term. Contrast sensu stricto (Lat.), in the narrowest, or most restricted sense of the term; e.g., Homo erectus (sensu stricto).

sexual dimorphism: Differences in body size and other structural traits between males and females of the same population. Pronounced in apes and early hominins, reduced in modern humans.

shoveling: Characterized by upper incisor teeth reinforced with extra enamel at their edges of the tongue side. Shovel-shaped incisors are typical of Homo erectus.

species: Groups of interbreeding natural populations reproductively isolated from other such groups; also, a protected gene pool with isolating mechanisms to protect itself from harmful gene flow from other populations (Mayr 1963).

speleothem: Mineral deposit formed in a cave by the influence of water.

stable isotope: One of two or more species of the same chemical element (having the same number of protons in the nucleus, but differing in the number of neutrons) that is not spontaneously radioactive.

subduction zone: Long narrow belt where one tectonic plate descends beneath another.

Sunda: Former subcontinent consisting of the Malaysian peninsula, Sumatra, the Indonesian islands, and the currently submerged continental shelf.

supramastoid crests: Points of attachment on the temporal bones above the mastoid processes for the temporal muscles (major chewing muscles).

supraorbital torus: Bony ridge above the eye sockets on a skull; very pronounced in Homo erectus, Neanderthals, and some australopithecines (from supra: above; orbital: eye; torus: ridge).

supratoral sulcus: Depression above the supraorbital torus.

sympatry: Two or more related species living in the same area.

talonid basin: Crushing or grinding surface on a lower tooth.

taphonomy: Study of the various natural activities that act on an animal bone from the death of the creature to the incorporation of the bone into a geological deposit as a fossil.

taxon (pl. taxa): Named group of organisms, formally distinguished from other groups.

taxonomy: System of classification involving the detailed ordering of taxa in a biological group.

temporal line: Area on the frontal bone of the skull where the temporal, a major chewing muscle, attaches; the temporal muscle then runs down the skull, passing through the zygomatic arch, ending up on the top back of the lower jaw.

temporal squama: A portion of the temporal bone, which is located at the side of the skull near the ear, the squama is flat or fanlike in modern humans and projects upward and forward.

tephra: Collective term for all clastic materials ejected from a volcano and transported through the air, including volcanic dust, ash, pumice, blocks, and bombs.

tephrostratigraphy: The arrangement and characteristics of volcanic strata as to their composition, geographic position, and chronological deposition.

Tethys corridor: Zone along the former Tethys ocean, which approximately occupied the current position of the mountain belt from the Alps to the Himalayas, at the edge of a continental plate.

tibia: Large long bone of the lower leg; the shin.

tragelaphine bovid: Member of the Tribe Tragelaphini of the Bovidae family, which includes modern spiral horned bovines, such as the greater kudu and nyala. They are mainly browsers on foliage, although they can also graze on grass.

trait complexes: Group of attributes or characters within a species for which heritable differences can be defined.

tuff lens: Body of tuff, or volcanic rock, that is thick in the middle and thin at the edges.

tuff: General term for all consolidated rocks formed by volcanic explosion or aerial expulsion from a volcanic vent.

unretouched flakes: Stone flakes as struck from primary core, without further edge modification.

uranium series (U-series) dating: Dating method based on the decay of a number of isotopes of uranium.

Villafranchian fauna: European animal assemblage spanning the late Upper Pliocene and Lower Pleistocene eras

wave-cut benches: Level to gently sloping narrow surfaces produced by wave erosion, extending outward from a wave-cut cliff, and developed mainly above water level by storm waves, weathering, and rainwash.

Y-chromosome: A chromosome unique to males, on which sex-determination genes are located, consisting largely of non-recombining sequence. Genetic variation on the Y-chromosome can show inheritance of specific genes or mutations through the paternal line, and also track male migrations through time and space.

zygomatic arch: Bone of the face forming the cheekbone, the outer portion of orbit (or eye socket), and its floor.

zygomaxillary border: Meeting place (or suture) where the zygomatic arch (cheekbone) meets the maxilla (upper jawbone).

(see also bibliography in Introduction to Homo erectus)

[Note: This glossary appears on pp.68-71 of  the printed issue of Athena Review (vol.4, no.1). Copyright 2004, Athena Publications, Inc.]

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