Archaeology & Evolution Glossary (B)

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z


 

B.P.: Before present.

backed blade: A blade (or flake) that is intentionally dulled on a margin so it can be hand-held safely.

bacteria: Spherical, rod-shaped, or spiral-shaped, single-cellular or multi-cellular, filamentous prokaryotic organisms.

balanced polymorphism: A multiplicity of forms in which the frequencies of the different variations do not differ significantly over time because of selection against the extremes (homozygotes).

balance model: A hypothesis of genetic variation proposing that balancing selection maintains large amounts of genetic variation within populations.

band: A simple form of human social organization, consisting of one or more families.

Barr body: A highly condensed mass of chromatin found in the nuclei of normal females, but not in the nuclei of normal male cells. It represents a cytologically condensed and inactivated X chromosome.

basalt: The fine-grained member of the gabbro family of igneous rock. Its mineral composition gives it a dark or black color.

base analog: A chemical whose molecular structure is extremely similar to the bases normally found in DNA.

base-pair substitution mutation: A change in a gene such that one base pair is replaced by another base pair; for instance, an AT is replaced by a GC pair.

basicranium: Base of the skull, formed mainly by the occipital, petrosal (of the temporal), and sphenoid bones.

basic research: Research done to further knowledge for knowledge’s sake.

basi-occiput: The most anterior portion of the occipital bone on the cranial base, the process that is in the front of the foramen magnum and meets the sphenoid.

basion (ba): The point where the anterior border of the foramen magnum crosses the midline.

bauplan: The basic inter-related structural characteristics of a species.

bed: In geology, a smal, distinct rock unit.

bending flake: A detached piece produced by cracks initiated away from the point of applied force. These flakes usually have a pronounced lip, contracting lateral margins immediately below the striking platform, and no bulb of force.

Bergmann’s Rule: Warm-blooded animals of similar shape tend to be larger in cold climates because larger animals tend to lose heat less rapidly than the smaller ones.

Beringia: The continent, or wide land bridge, spanning the Bering Strait between Alaska and Siberia at times of low sea level, including contiguous parts of both.

beveled: Usually referred to as a tool edge that has been modified by the removal of a series of flakes to produced a desired edge angle.

biceps brachialis muscle: Muscle extending from below the humerus midshaft, across the front of the elbow, and attaching on the top of the ulna. It flexes the elbow.

biceps brachii muscle: A two-joint muscle extending from the scapula (two attachments) across the shoulder and elbow joints, to the radial tuberosity. It can flex the humerus and rotate the forearm, most effectively suppinating it.

bicondylar angle: The angle from vertical that the shaft of the femur makes when the bone is stood upright on its condyles.

bicuspid: A premolar tooth.

bidirectional replication: The DNA synthesis that takes place in both directions away from the origin of the replication point.

biface: A tool that has two surfaces (faces) that heet to form a single edge that circumscribes the tool. Both faces usually contain flake scars that travel at least half-way across the face.

bifacial thinning flake: A flake that is removed during biface trimming and often contains a striking platform, that is rounded or ground, indicating preparation. It is usually thin relative to width, with a feathered termination.

bilateral kinship: Kinship traced to relatives through both father and mother.

bilateral symmetry: Anatomical features for which the right and left sides are close to being mirror images of one another.

billet: A baton or club, of material other than rock, used to detach flakes from an objective piece by percussion. It is usually made of antler, wood, or bone.

bilophodont: Teeth with two crests, a type of molar construction in which there are two parallel enamel ridges on the occlusal surface, running from side to side connecting the cusps.

binocular vision: Overlapping fields of vision in which both eyes can focus on a distant object to produce a stereoscopic (three-dimensional) image.

binomial distribution: The theoretical frequency distribution of events that have two possible outcomes.

biochemical mutation: See auxotrophic mutation.

biological species: Defines a species as a reproductively isolated aggregate of populations which can actually or potentially inetrbreed and produce fertile offspring. The concept focuses on the importance of reproductive isolation and the anatomical and behavioral mechanisms that create it.

biomass: The total weights of all living things in a particular area.

biomechanics: Pertaining to the physics of the skeletal system, especially its static and dynamic analyses.

biostratigraphy: Sequential or temporal ordering of strata based on the fossils they contain.

biparental inheritance: Plant zygotes that show traits indicating chloroplast chomosomes from both parents are present and active.

bipedal: Two-legged.

bipolar flake: A detached piece formed as a result of compression forces. Bipolar flakes often show signs of impact on opposing ends and have compression rings moving in two directions toward one another.

bipolar technique: Removal of flakes from a core resting on a hard surface, giving the flakes different thickness characteristics and the core a unique form because there is a shockwave from percussion at both ends. A technique of resting the objective piece on an anvil and striking it with a hammer to split or remove a detached piece.

bivalent: A pair of homologous, synapsed chromosomes during the first meiotic division.

blade tool: An artifact formed on a parallel-sided stone flake, usually removed from a carefully prepared core but defined as any flake whose length is more than double its breadth.

blank: A detached piece potentially modifiable into a specific tool form.

bonobo: A supposed species of chimpanzee, Pan paniscus, that live in forested habitats of Central Africa south of the Zaire River; the closest living relative of the common chimpanzee, Pan troglodytes.

boss: A round, broad, bulging eminence on cranial bones.

bottleneck: A form of genetic drift that occurs when a population is drastically reduced in size. Some genes may be lost from the gene pool as a result of chance.

bovid: A member of the family Bovidae, cloven-hoofed ungulates (bison, antelopes, deer, goats, sheep, etc.). Most bones found at African sites are bovid.

bowing (limb shaft bowing): Curvature of the long bone shaft in the anterior-posterior plane.

Brachial Index: Ratio of the length of the forearm divided by the length of the upper arm (radius/humerus*100).

brachiation: Arm-over-arm arboreal locomotion in which the animal progresses below-branches by swinging its body between forelimn supports.

brachycephalic: Broad-headed, having a Cephalic Index (cranial breadth/cranial length*100) over 80.

branch-point sequence: The consenus sequence in mammalian cells, YNCURA, (where Y is a pyrimidine, R is a purine, and N is any base) to which the free 5′ end of the intron loops and binds to the A nucleotide in the sequence during intron splicing.

breccia: Sedimentary rock composed of angular fragments of derived material cemented together, often the main component of cave or fissure fillings.

bregma (b): The point at the top of the head where the coronal and sagittal sutures of the skull meet, or where the two parietal bones meet with the frontal.

bregmatic (prebregmatic) eminence: Small prominence on the cranial midline at or near bregma.

bridewealth: Marriage payments from the husband and his kin to the bride’s kin. Characteristically these payments balance a transfer of rights over the wife’s sexuality, work services, residence, fertility, and so on.

broad-sense heritability: A quantity representing the proportion of the phenotypic variance that consists of genetic variance.

Broca’s area: A cortical region of the human brain located on the side of the frontal lobe, just above the temporal lobe (directly beneath a finger placed at the temple). This area is important in speech production and injury to it will result in aphasia (language dyfunction).

browridge: A thickened ridge or shelf of bone above the orbits at the base of the forehead, continuously, although not necessarily evenly, developed from the middle of the cranium to each side.

buccal: The cheek-facing side of a postcanine tooth.

bulb of force: bun (occipital bun): A backward extension of the cranial rear in the form of a protuberance bounded by the nuchal plane below, a short vertical face for the occiput behind, and a flat surface above (lambdoidal flattening).

bunodont: Teeth with low, rounded cusps.

burin: A chisel-like stone tool for engraving bone, wood, horn, or soft-stone.

Bibliography

Andrefsky, W., Jr. 1998. Lithics: Macroscopic Approaches to Analysis. Cambridge: Cambridge University Press.
Keesing, R.M. 1975. Kin Groups and Social Structure. Fort Worth: Harcourt Brace.
Renfrew, C., and P. Bahn. 1996. Archaeology: Theories, Methods, and Practice. New York: Thames and Hudson Inc.
Russell, P.J. 1998. Genetics. Menlo Park: Addison Wesley Longman, Inc.
Wolpoff, M. 1999. Paleoanthropology. second edition. Boston: McGraw-Hill.