sacral vertebrae: The fused vertebrae that make up the sacrum, at the back of the pelvis.
sacroiliac joint: The joint at the back of the pelvis between the sacrum and the ilium.
sagittal (plane): A vertical plane on the midline that divides the body into a right and left half.
sagittal crest: A compound crest of bone running along the midline of the skull for attachment of enlarged temporalis muscles that meet along the midline.
sagittal keel (torus): A thickening of the bone on all or part of the midline of the frontal or parietals where they meet sagittally, or both bones.
Sahul: The name given to the continent formed when Australia is connected to New Guinea, during the low water level of a glaciation, also used to describe the region.
saltation: Discontinuous variation produced all at once by major mutation.
sample: The subset used to give information about a population. It must be of reasonable size and it must be a random subset of the larger group in order to provide accurate information about the population.
sampling error: A change in gene frequencies between parents and offspring in a population that is due to the small size of each generation when populations themselves are small. Small samples usually do not exactly duplicate the characteristics of the large population they are drawn from.
sandstone: A cemented or compacted detrital sediment composed predominantly of quartz grains the size of sand particles.
sartorius: A muscle extending from the anterior superior iliac spine to the medial side of the proximal tibia, flexing the hip and knee joints.
satellite DNA: The DNA that forms a band in an equilibrium density band that is distinct from the band constituting the majority of the genomic DNA as a result of a different buoyant density.
savanna: A plain characterized by coarse grasses and scattered trees, often with seasonal rainfall.
scanning electron microscope (SEM): An instrument for analyzing the surfaces of tiny structures by using a focused beam of electrons to produce an enlarged image.
scapula: The flat, triangular bone at the back of the shoulder.
scapular spine: The projecting structure extending transversely across the back of the scapula, holding the attachment for muscles such as the deltoid and trapezius, and terminating in the acromion process that meets the clavicle.
scraper: A generalized term used to describe a flake tool that has a retouched edge angle of approximately 60º to 90º.
seasonality: Aspects of the environment, or of adaptations to it, that differ from one time of year to another.
secondary nondisjunction: A nondisjunction of the Xs in the progeny of females that were produced by a primary nondisjunction.
secondary oocyte: A large cell produced by the primary oocyte. In the ovaries of female animals the diploid primary oocyte goes through meiosis I and unequal cytokinesis to produce two cells; the large cell is called the secondary oocyte.
secondary sexual characteristics: Gender-related features, not directly involved in reproduction, that develop at or after puberty.
second law: See principle of independent assortment.
second-site mutation: See suppressor mutation.
section system: in alliance thoery and Australian kinship studies, division of a society into two, four, or eight social categories through rules of descent and allaiance. Symmetrical rules of marital allaince, enjoining marriage with a member of one of the sections, are a normal accompaniment of such systems.
sectorial (tooth crown): Tooth with an elliptical or circular cross-section and a single cusp; in anthropoids, generally referring to the lower anterior premolar wich wears against the overlapping upper canine, creating a honing facet on the premolar’s mesial surface from cutting against the distal edge of the canine in a scissors-like action.
sedentary: Settling permanently in one place.
sedimentary rock: A rock composed of the by-products of other rocks that have been eroded or dissolved. Examples of sedimentary rocks are sandstone, mudstone, halite, and chert.
sedimentology: A subset of geomorphology concerned with the investigation of the structure and texture of sediments, i.e., the global term for material deposited on the earth’s surface.
segmentary societies: Relatively small and autonomous groups, usually of agriculturalists, who regulate their own affairs; in some cases, they may join together with other comparable segmentary societies to form a larger ethnic unit.
selection: See natural selection.
selection coefficient: A measure of the relative intensity of selection against a genotype.
selection differential: In natural and artificial selection, the difference between the mean phenotype of the selected parents and the mean phenotype of the unselected population.
selection response: The amount that a phenotype changes in one generation when selection is applied to a group of individuals.
self-fertilization (selfing): The union of male and female gametes from the same individual.
self-organization: The product of a theory derived from thermodynamics which demonstrates that order can arise spontaneously when systems are pushed far from an equilibrium state. The emergence of new structure arises at bifurcation points, or thresholds of instability.
self-splicing: The excision of introns from some precursor RNA molecules that occur by a protein-independent reaction in some organisms.
semiconservative replicative model: A DNA replication scheme in which each daughter molecule retains one of the parental strands.
semidiscontinuous: Concerning DNA replication, when one new strand is synthesized continuously and the other discontinuously. See also discontinuous DNA replication.
semispinalis capitis: A muscle of the nuchal region travelling down the back where it attaches to cervical and thoracic vertebrae, important in extending and stabilizing the head (for instance in conjunction with anterior tooth loading).
semitendinosus: One of the hamstring muscles, which extend the thigh and flex the leg.
sense codon: A sense codon, as opposed to a nonsense codon, in an mRNA molecule specifies an amino acid in the corresponding polypeptide.
sensory area: One of the three areas of the cerebral cortex devoted to reception of information from the body’s senses.
sequence tagged site (STS): A short segment of DNA that defines a unique position in the human genome; an STS is usually detected by the polymerase chain reaction.
seriation: Placement in an order (chronological, developmental, etc.).
serrate pattern: The combination of a very large vertically oriented mesial molar root with a smaller distal root angled both distally and in a buccal direction.
sesamoid: A bone formed within a tendon.
settlement pattern: Distribution of semi-permanent or permanent human habitations on the landscape and within archaeological communities.
sex chromosome: A chromosome in eukaryotic organisms that is represented differently in the two sexes. In many organisms, one sex possesses a pair of visibly different chromosomes. One is an X chromosome, and the other is a Y chromosome. Commonly, the XX sex is female and the XY is male.
sex-influenced traits: The traits that appear in both sexes but either the frequency of occurrence in the two sexes is different or there is a different relationship between genotype and phenotype.
sex-limited trait: A genetically controlled character that is phenotypically exhibited in only one of the two sexes.
sex-linked: See X-linked.
sex-linked character: A feature whose expression is controlled by genes located on the sex chromosomes.
sexual dimorphism: A polymorphic character in which males and females of a species differ in some aspect of their anatomy not directly related to reproduction or birth.
sexual reproduction: The reproduction involving the fusion of haploid gametes produced by meiosis.
sexual selection: The increased reproductive success of males or females because of characters that enhance either their ability to compete with members of the same sex or their attractiveness to members of the opposite sex.
shaft: The long part of long bone, formed from the diaphyses.
shale: A sedimentary rock formed by the cementation of very fine particles sich as mud or silt.
shear: In chewing, the action resulting from applied forces created when tooth surfaces slide relative to each other, a cutting force.
shovel-shaped incisors: Incisors that have a scooped out lingual surface because of lingual marginal ridges, crown curvatures, or a basal tubercle alone or in combination.
shuttle vector: A cloning vector that can replicate in two or more host organisms. Shuttle vectors are used for experiments in which recombinant DNA is to be introduced into organisms other than E. coli.
sialic rocks: Refers to igneous rocks light in color because of light minerals such as quartz.
sigmoid notch: See trochlear notch.
signal hypothesis: The hypothesis that the secretion of proteins from a cell occurs through the binding of a hydrophobic amino terminal extension to the membrane and the subsequent removal and degradation of the extension in the cisternal space of the endoplasmic reticulum.
signal peptidase: An enzyme in the cisternal space of the ER that catalyzes removal of the signal sequence from the polypeptide.
signal recognition particle (SRP): In eukaryotes, a complex of a small RNA molecule with six proteins, which can temporarily halt protein synthesis by recognizing the signal sequence of a nascent polypeptide destined to be translocated through the ER, binding to it, and hereby blocking further translation of the mRNA.
signal sequence: The hydrophobic, amino terminal extension found on proteins that are secreted from a cell. The amino terminus (extension) is removed and degraded in the cisternal space of the endoplasmic reticulum.
silencer: See silencer element.
silencer element: In eukaryotes, a transcriptional regulatory element that decreases RNA transcription rather than stimulating it like other enhancer elements.
silent mutation: A mutational change resulting in a protein with a wild-type function because of an unchanged amino acid sequence.
silica: A term used to describe silicon dioxide.
silicified: Refers to a rock hardened by silica.
siltstone: See shale.
simian: Referring to any member of Anthropoidae (monkeys, humans, apes).
simian shelf: See mandibular torus.
simple random sampling: A type of probabilistic sampling where areas to be sampled are chosen using a table of random numbers. Drawbacks include: (1) defining the site’s boudaries beforehand (2) the nature of random number tables results in some areas being allotted clusters of sample squares, while others remain untouched.
simple telomeric sequences: Simple, tandemly repeated DNA sequences at, or very close to, the extreme ends of the chromosomal DNA molecules.
SINEs (short interspersed repeated sequences): One class of interspersed and highly repeated sequences that consist of dispersed families with unit lengths of fewer than 500 base pairs and repeated for as many as hundreds of thousands of copies in the genome.
Single Species Hypothesis: The theory that only one hominid species at a time could be expected because culture should so broaden hominid niches that competition for limiting resources between species would be inevitable and lead to enhanced cultural abilities and further niche broadening. Only one of the competing species would be expected to persist. The hypothesis rests on the assumption that all manifestations of culture result in effective niche expansion.
single-strand DNA binding (SSB) proteins (helix-destabilizing proteins): Proteins that help the DNA unwinding process by stabilizing the single-stranded DNA.
sinus: A pocket or cavity within a cranial bone, also applied to describe the grooved pathways for blood vessels on the endocranial surface.
sister chromatid: A chromatid derived from replication of one chromosome during interphase of the cell cycle.
sister exchange: Exchange of sisters in marriage by a pair of men.
sister groups: Two groups that result from a single split in a cladogram; they, and only they, share the same parent taxon.
site: A distinct spatial clusterin of artifacts, features, structures, and organic and environmental remains, as the residue of human activity.
site catchment analysis (SCA): A type of off-site analysis, which concentrates on the total area from which a site’s contents have been derived; at its simplest, a site’s catchment can be thought of as a full inventory of artifactual and non-artifactual remains and their sources.
site exploitation territory (SET): Often confused with site catchment analysis, this is a method of achieving a fairly standardized assessment of the area habitually used by a site’s occupants.
skull: The bony skeleton of the head, including the lower jaw.
slate: A metamorphosed shale that breaks along flat planes.
slope (regression coefficient): The change in one variable (y) associated with a unit increase in another variable (x).
small nuclear ribonucleoprotein particles (snRNPs): The complexes formed by small nuclear RNAs and proteins in which the processing of pre-mRNA molecules occurs.
small nuclear RNA (snRNA): Found only in eukaryotes, one of four major classes of RNA molecules produced by transcription, snRNAs are used in the processing of pre-mRNA molecules.
sociobiology: The study of the biological basis of all social behavior.
soft hammer: This usually refers to a billet but may include hammerstones of very soft materials such as mudstone.
soft percussion (soft hammer): An Acheulean technology that used wood, bone, or antler instead of rock to chip flakes from a core.
somatic cell hybridization: The fusion of two genetically different somatic cells of the same or different species to generate a somatic hybrid for genetic analysis.
somatic mutation: A mutation in a cell that produces a mutant spot or area, but the mutant characteristic is not passed on to the succeeding generation.
sororate: A form of secondary marriage whereby, upon the death of a wife, her sister or some other close relative marries the surviving husband. This perpetuates the marital contract between groups.
Southern blot technique: A technique invented by E.M. Southern and used in analyzing genes and gene transcripts, in which DNA fragments are transferred from a gel to a nitrocellulose filter.
spacer sequences: Transcribed sequences that are found between, and flanking, coding RNA sequences. Spacer sequences are removed during processing or pre-rRNA and pre-tRNA to produce mature molecules.
spatulate: Spade-like, referring to upper incisors that are broad, often with marginal ridges along the edges of their internal surface.
specialized: (1) Derived or apomorphic, differing from the ancestral condition; (2) adapted to a limited range of resources.
specialized transducing phage: A temperate bacteriophage that can transduce only a certain section of the bacterial chromosome.
specialized transduction: A type of transduction in which only specific genes are transferred.
speciation: The process whereby species multiply; the acquisition of reproductive isolation between populations, splitting one species into two.
species: In living animals a group of populations (Biological species) that can actually or potentially interbreed and have fertile offspring, and are reproductively isolated from other species. Also see Evolutionary, Genealogical, Morpho-, and Phylogenetic species.
spermatogenesis: Development of the male animal germ cell within the male gonad.
sperm cells (spermatozoa): The male gametes; the spermatozoa produced by the testes in male animals.
sphenoid bone: Irregularly shaped bone forming part of the base and sides of the skull and the back of the orbit.
sphere of exchange: In non-market societies, prestige valuables and ordinary commodities were often exchanged quite separately, i.e., valuables were exchanged against valuables in prestige transactions, while commodities were exchanged against commodities with much less ceremony, in mutally profitable barter transactions. These separate systems are termed spheres of exchange.
spine: A sharp projection or short ridge.
spliceosomes: The splicing complexes formed by the association of several snRNPs bound to the pre-mRNA.
splitter: One who emphasizes differences and formalizes variation al lower taxonomic levels (cf. lumper).
spongy bone: See cancellous bone.
spontaneous mutations: The mutations that occur without the use of chemical or physical mutagenic agents.
sporophyte: The haploid, asexual generation in the life cycle of plants that produces haploid spores by meiosis.
squama: The flat portion of a cranial bone.
squamosal suture: Suture between the parietal and temporal bones, in the form of a beveled edge with the temporal overlapping on the outside.
stadial: A cold period during a glaciation.
stamen: The male reproductive organ in a flowering plant that usually consists of a stalk, called a filament, bearing a pollen-producing anther.
standard deviation: Approximately, the mean difference between all of the data points in a sample and their average. Formally the square root of the variance (V), where
V = S(|Xi – Xav|)2/(n – 1)
Xi is each data point, Xav is the mean of the points, and n is the number of points.
standard error of gene frequency: A measure of the amount of variation among the gene frequencies of populations. It is the square root of the variance of gene frequency.
stasis: Little or no evolutionary change occurring over a long period of time; see also punctuated equilibrium.
state: A term used to describe a social formation defined by distinct territorial boundedness, and characterized by strong central government in which the operation fo political power is sanctioned by legitimate force. In cultural evolutionist models, it ranks second only to the empire as the most complex societal development state.
stela: A free-standing carved stone monument.
step fracture: The scar left on the objective piece after a previous flake has been detached with step termination.
step termination: The distal end of a flake that terminates abruptly in a right-angle break. This creates a “step-like” break, not to be confused with hinge termination.
sternocleidomastoid muscle: Extends from the mastoid process and superior nuchal line to the sternum and the clavicle, rotating and stabilizing the head.
steroid response element (REs): The DNA sequence to which steroid hormones will bind to activate a gene.
stone tool: An artifact that has been intentionally modified by retouch or unintentionally modified by usewear. Examples of stone tools are projectile points, unifaces, scrapers, and microliths. Debitage would not be considered tools, but would be considered artifacts.
stop codon: See chain-terminating codon.
stratification: The laying down or depositing of strata or layers (also called deposits) one above the other. A succession of layers should provide a relative chronological sequence, with the earliest at the bottom and the latest at the top.
stratified random sampling: A form of probabilistic sampling in which the region or site is divided inot natural zones or strata such as cultivated land and forest; units are then chosen by a random number procedure so as to give each zone a number of squares proportional to its area, thus overcoming the inherent bias in simple random sampling.
stratified systematic sampling: A form of probabilistic sampling which combines elements of (1) simple random sampling (2) startified random sampling (3) systematic sampling, in an effort to reduce sampling bias.
stratigraphy: The location or position of fossil or other deposits relative to other buried layers or features.
striking platform: The surface are of an objective piece recieving the force to detach a piece of material. This surface is often removed with the detached piece so that the detached piece will contain the strking platform at the point of applied force.
structural gene: A gene that codes for an mRNA molecule and hence for a polypeptide chain.
stylohyoid ligament: A ligament extending from the styloid process on the cranial base to the hyoid bone.
styloid process: A pencil shaped, pointed process of bone that rests in the vaginal foramen of the temporal petrous, fusing with it in older individuals. It is the seat of attachment for the stylohyoid ligament.
subadults: An age category, young individuals including infants, children, and juveniles.
subchron: A short period (10 – 100 kyr) of polarity reversal within a chron.
subfossil: Recent, often only partially fossilized, remains often from the Holocene or historical times.
submetacentric chromosome: A chromosome that has the centromere nearer one end than the other. Such chromosomes appear J-shaped at anaphase.
subnasal alveolar process: Part of the anterior maxilla below the nose, housing the roots of the upper incisors.
subspecies: A geographically defined aggregate of local populations which differs with various degrees of significance (depending on the author) from other such subdivisions of the species.
subtrochanteric: Below (or distal to) the position of the trochanter.
sulcus: A broad groove; on the brain’s surface the sulci are the valleys between the gyri.
sum rule: The rule that the probability of either one of two mutualy exclusive events occurring is the sum of their individual probabilities.
Sunda: The name for the region of mainland Southeast Asia and the western Indonesian islands. This area is a single land mass during the low sea levl of glaciation.
superciliary arches: Smoothly rounded bulges of bone found on the frontal bone of the skull at its center and extending over the inner portion of the upper orbital border.
supination: Rotation of the forearm so that the palm faces upward; the reverse movement from pronation.
suppressor gene: A gene that causes suppression of mutations in other genes.
suppressor mutation: A mutation at a second site that totally or partially restores a function lost because of a primary mutation at another site.
suprainiac fossa: An elliptical depression on the occiput above the superior nuchal line, or inion.
supramastoid: The pneumatized region on the temporal bone just above the mastoid process base. It marks the backward extension of the root of the zygomatic process of the temporal.
supraorbital torus: 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.
supraspecific: Above the species level.
supratoral sulcus: A broad depression or groove between the browridges and the frontal bone, creating an angle between the top of the browridge and the front of the orbital squama.
suspensory: Hanging, locomotor and postural habits with the body below or among branches.
Sutural bone: See Wormian bone.
suture: A joint where two bones interdigitate and are separated by fibrous tissue. The joints between most of the bones of the skull are sutures. Most sutures join and the bones eventually fuse together as individuals grow older.
Svedberg units (S values): The conversions for sedimentation rates in sucrose density centrifugation. Svedberg units are used as a rough indication of relative sizes of the components being analyzed.
symmetrical alliance: In alliance theory, a marriage system involving direct exchange.
sympatric speciation: Speciation without geographic isolation with isolating mechanisms developing within populations.
sympatry: The occurrance of two or more poulations (species, etc.) in the same area.
symphyseal angle: The angle made by the mandibular symphysis face and the lower border of the body, such as the mandibular symphysis and pubic symphysis.
symphysis: A flexible fibrocartilaginous joint found on the middle of the body, such as the mandibular symphysis and the pubic symphysis.
symplesiomorphy: The sharing of ancestral characters by several species.
synapomorphy: The sharing of apomorphies, or derived characters, by two or more species.
synapsis: The intimate association of homologous chromosomes brought about by the formation of a zipperlike structure along the length of the chromatids called the synaptonemal complex.
synaptonemal complex: A complex structure spanning the region between meiotically paired (synapsed) chromosomes that is concerned with crossing-over rather than with chromosome pairing.
synchronic: Referring to phenomena considered at a single point in time; i.e., an approach which is not primarily concerned with change (c.f. diachronic).
synkaryon: A fusion nucleus produced following the fusion of cells with genetically different nuclei.
synostosis: The joining of separate pieces of bone in human skeletons; the precise timing of such processes is an important indicator of age.
syntenic: The genes that are localized to a particular chromosome by using an experimental approach (literally “together thread”; the term is similar to linked).
systematics: The science of the diversity of organisms and their relationships and classification.
systematic sampling: A form of probabilistic sampling employing a grid of equally spaced locations; e.g., selecting every other square. This method of regular spcaing runs the risk of missing (or hitting) every single example if the distribution itself is regularly spaced.
systems thinking: A method of formal analysis in which the object of study is viewed as comprising distinct analytical sub-units. Thus in archaeology, it comprises a form of explanation in which a society or culture is seen through the interaction and interdependence of its component parts; these are referred to as system parameters, and may include such things as population size, settlement pattern, crop production, technology, etc.
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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.