talonid: A distal shelf on a tooth.
talus (astragalus): Anklebone.
taphonomy: Study of the processes that effect the remains of organisms from the death of an organism through its fossilization.
tarsals: Small bones of the ankle and foor. In humans these are the talus, calcaneus, navicular, cuboid, and three cuneiforms.
TATA element: See Goldberg-Hogness box.
taurodont: Teeth having enlarged pulp cavities in their roots.
tautomeric shift: The change in the chemical form of a DNA (or RNA) base.
tautomers: Alternate chemical forms in which DNA (or RNA) bases are able to exist.
taxon: A monophyletic group of organisms recognized as a formal unit, at any level of a hierarchic classification.
taxonomy: The theory and practice of classifying organisms.
technology: The techniques used to produce artifacts.
tectonic movements: Displacements in the plates that make up the earth’s crust, often responsible for the occurrence of raised beaches.
tektites: Streamlined glassy objects found in some soils that result from meteoric impacts that throw silicon-rich material into the upper atmosphere that fuses into a glass as it heats up during its return.
tell: A Near Eastern term that refers to a mound site formed through successive human occupation over a very long time span.
telocentric chromosome: A chromosome that has the centromere more or less at one end.
telomere-associated sequences: Repeated, complex DNA sequences extending from the molecular gene of chromosomal DNA, suspected to mediate many of the telomere-specific interactions.
telophase: A stage during which the migration of the daughter chromosomes to the two poles is completed.
telophase II: The last stage of meiosis II during which a nuclear membrane forms around each set of chromosomes, and cytokinesis takes place.
template strand: The unwound single strand of DNA on which new strands are made (following complementary base pairing rules).
temporal bone: Complex bone on the side and base of the cranium that includes the ear, mandibular joint, and a portion of the side of the braincase.
temporal fossa: The space enclosed by the side of the skull and the zygomatic arch, which is occupied by the temporalis muscle as it passes from its mandibular attachment to its attachment on the cranium.
temporal line: The line caused by the edge of the temporalis muscle where it attaches along the cranial vault. There are two lines, an inferior line from the deep part of the muscle and a superior line from the superficial part.
temporalis muscle: A fan-shaped muscle that moves the jaw in mastication and creates force between the teeth, joining the inside of the mandibular ramus and the side and rear of the skull.
temporonuchal crest: A compound crest on the back of the skull formed by convergence of the temporal line of the nuchal crest.
tendon: A strong, inelastic cord of connective tissue joining muscle to bone.
tephra: Volcanic ash. In the Mediterranean, for example, deep-sea coring produced evidence for the ash fall from the eruption of Thera, and its stratigraphic location provided important information in the construction of a relative chronology.
termination factors (release factors; RF): The specific proteins in polypeptide synthesis (translation) that read the chain termination codons and then initiate a series of specific events to terminate polypeptide synthesis.
terminations: In glacial studies, the midpoints in deglaciations leading to interglacial periods.
terminator: See transcription terminator sequence.
terrestrial: On the ground.
terrestrial quadruped: Ground-living animal that moves about primarily on all four limbs.
territory: Part of a home range that is exclusive to a group of animals and is actively defended from other groups of the same species.
testcross: A cross of an individual of unknown genotype, usually expressing the dominant phenotype, with a homozygous recessive individual in order to determine the genotype of the individual.
testis-determining factor: Gene product in placental mammals that sets the switch toward male sexual differentiation.
tetrad analysis: Genetic analysis of all the products of a single meiotic event. Tetrad analysis is possible in those organisms in which the four products of a single nucleus that has undergone meiosis are grouped together in a single structure.
tetrasomy: The aberrant, aneuploid state in a normally diploid cell or organism in which an extra chromosome pair results in the presence of four copies of one chromosome type and two copies of every other chromosome type.
tetratype (T): One of the three types of tetrads possible when two genes are segregating in a cross. The T tetrad contains two parental and two recombinant nuclei, one of each parental type and one of each recombinant type.
thermoluminescence (TL): A dating technique that relies indirectly on radioactive decay, overlapping with radiocarbon in the time period for which it is useful, but also has the potential for dating earlier periods. It has much in common with electron spin resonance (ESR).
Thiessen polygons: A formal method of describing settlement patterns based on the territoral divisions centered on a single site; the polygons are created by drawing straight lines between pairs of neighboring sites, then at the mid-point along each of these lines, a second series of lines are drawn at right angles to the first. Linking the second series of lines creates the Thiessen polygons.
thin-section analysis: A technique whereby microscopic thin sections are cut from a stone object or potsherd and examined with a petrological microscope to determine the source of the material.
thoracic: Pertaining to the thorax (chest), especially the ribbearing vertebrae below the cervical and above the lumbar vertebrae.
Three Age System: A classification system devised by C.J. Thomsen for the sequence of technological periods (stone, bronze, and iron) in Old World prehistory. It established the principle that by classifying artifacts, one could produce a chronological ordering.
three-point testcross: A test involving three genes within a relatively short section of the chromosome. It is used to map genes for their order in the chromosome and for the distance between them.
thymine (T): A pyrimidine base found in DNA but not in RNA. In double-stranded DNA, thymine pairs with adenine.
tibia: Long bones of the lower leg, between the knee and the foot.
tomography: A CAT scan is a radiographic technique that can display “slices” taken through bones or skulls that will show the shape and extent of internal cavities.
tool: An artifact with a functional use. Curated tools are kept for use in the future, while expedient tools are made in response to an immediate need.
toothpick grooves: Elongate grooves between adjacent teeth, usually on the roots just below the crown level and marked on their facing sides.
topoisomerases: A class of enzymes that catalyze the supercoiling of DNA.
torus: A smooth rounded ridge or protuberance.
totemism: Symbolic association between a social group (e.g., a lineage or clan) and a kind of bird, plant, or natural phenomenon. In “classic” forms, a member of the social group has some special religious relationship (e.g., a food taboo) toward members of the natural species.
totipotency: The capacity of a nucleus to direct events through all the stages in development and therefore produce a normal adult.
trabecular bone: See cancellous bone.
trace element analysis: The use of chemical techniques, such as neutron activation analysis, or X-ray fluorescence spectrometry, for determining the incidence of trace elements in rocks. These methods are widely used in the identification of raw material sources for the production of stone tools.
trailer sequenc: The sequence of the mRNA molecule beginning at the end of the amino acid-coding sequence and ending at the 3′ end of the mRNA. The trailer sequence is not translated and varies in length from molecule to molecule.
trajectory: In systems thinking, this refers to the series of successive states though which the system proceeds oevr time. It may be said to represent the long-term behavior of the system.
transconjugants: In bacteria, the recipients inheriting donor DNA in the process of conjugation.
transcription: The transfer of information from a double-stranded DNA molecule to a single-stranded RNA molecule. It is also called RNA synthesis.
transcriptional control: The first level of control of gene expression in eukaryotes. This level involves regulating whether or not a gene is to be transcribed and the rate at which transcripts are produced.
transcription factors (TFs): Specific proteins that are required for the initiation of transcription by each of the three eukaryotic RNA polymerases. Each polymerase uses its own set of TFs.
transcription terminator sequence (terminator): A transcription regulatory sequence located at the distal end of a gene that signals the termination of transcription.
transdetermination: During development, a process whereby an imaginal disc does not totally dedifferentiate but switches to another determined path.
trans-dominant: The phenomenon of a gene or DNA sequence controlling genes that are on a different piece (strand) of DNA.
transducing phage: The phage that is the vehicle by which genetic material is shuttled between bacteria.
transducing retroviruses: Retroviruses that have picked up an oncogene from the cellular genome.
transductants: In bacteria, the recipients inheriting donor DNA in the process of transduction.
transduction: A process by which bacteriophages mediate the transfer of bacterial genetic information from one bacterium (the donor) to another (the recipient); a process whereby pieces of bacterial DNA are carried between bacterial strains by a phage.
transfer RNA (tRNA): One of the hour classes of RNA molecules produced by transcription and involved in protein synthesis; molecules that bring amino acids to the ribosome, where they are matched to the transcribed message on the mRNA.
transformant: The genetic recombinant generated by the transformation process.
transformation: 1) A process in which genetic information is transferred by means of extracellular pieces of DNA in bacteria 2) The failure of cells to remain constrained in their growth properties and give rise to tumors.
transgene: A gene introduced into the genome of an organism by genetic manipulation in order to alter its genotype.
transgenic organism: An organism that has had its genotype altered by the introduction of a new gene into its genome by genetic manipulation.
transitional mutation: A specific type of base-pair substitution mutation that involves a change in the DNA from one purine-pyrimidine base pair to the other purine-pyrimidine base pair at a particular site (e.g., AT to GC).
transit peptidase: The enzyme that removes transit sequences from proteins transported into organelles.
transit sequences: The extra sequences at the N-terminal ends of proteins that are necessary and sufficient for posttranslational transport into organelles.
translation (protein synthesis): The conversion in the cell of the mRNA base sequence information into an amino acid sequence of a polypeptide.
translational control: The regulation of protein synthesis by ribosome synthesis among mRNAs.
translocation (transposition): 1) A chromosomal mutation involving a change in position of a chromosome segment (or segments) and the gene sequences it contains 2) In polypeptide synthesis, translocation is the movement of the ribosome, one codon at a time, along the mRNA toward the 3′ end.
transmission genetics (classical genetics): A subdivision of the science of genetics primarily dealing with how genes are passed from one individual to another.
transport control: Regulating the number of transcripts that exit the nucleus to the cytoplasm.
transposable element: A genetic element of chromosomes of both prokaryotes and eukaryotes that has the capacity to mobilize itself and move from one location to another in the genome.
transposase: A enzyme encoded by the IS element of a transposon that calalyzes transposition activity of a transposable element.
transposon (Tn): A mobile DNA segment that contains genes for the insertion of the DNA segment into the chromosome and for mobilization of the element to other locations on the chromosomes.
transverse torus: See superior mandibular torus or inferior mandibular torus.
transversion mutation: A specific type of base-pair substitution mutation that involves a change in the DNA from a purine-pyrimidine base pair to a pyrimidine-purine base pair at the same site (e.g., At to TA or GC to TA).
trapezius muscle: A muscle extending from the nuchal plane to the clavicle and scapula that stabilizes the shoulder and brings the scapula upwards.
travertine: A calcium carbonate rock deposited around lime-rich springs and lakes.
tribes: A term used to describe a social grouping generally larger than a band, but rarely outnumbering more than a few thousand; unlike bands, tribes are usually settled farmers, though they also include nomadic pastoral groups whose economy is based on exploitation of livestock. Individual communities tend to be integrated into the larger society through kinship ties.
trihybrid cross: A cross between individuals of the same type that are heterozygous for three pairs of alleles at three different loci.
trisomy: An aberrant, aneuploid state in a normally diploid cell or organism in which there are three copies of a particular chromosome instead of two copies.
trisomy-21: A human clinical condition characterized by various abnormalities. It is caused by the presence of an extra copy of chromosome 21.
trochanter: A larger process, for muscle attachment.
trochlea: Any smooth, saddle-shaped bony surface that forms part of a joint.
trochlear (sigmoid) notch: The notch within the hook-like proximal end of the ulna that slides in and out of the olecranon fossa of the humerus.
true-breeding (pure-breeding) strain: A strain allowed to self-fertilize for many generations to ensure that the traits to be studied are inherited and unchanging.
true reversion: A point mutation from mutant back to wild type in which the change codes for the original amino acid of the wild type.
tubercle: A small eminence.
tuff: A consolidated deposit of volcanic ash, transported to the site by air or more often water.
tumor viruses: Viruses that induce cells to dedifferentiate and to divide to produce a tumor.
Turner syndrome: A human clinical syndrome that results from monosomy for the X chromosome in the female, which gives a 45,X female. These females fail to develop secondary sexual characteristics, tend to be short, have weblike necks, have poorly developed breasts, are usually infertile, and exhibit mental deficiencies.
twin spots: Two adjacent cell groups that differ in genotype and phenotype. They result from mitotic crossing-over within the somatic cells of a heterozygous individual.
tympanic bone: The portion of the temporal bone that encloses the inner ear.
tympanic crest: See petrosal crest.
tympanic membrane: Eardrum.
type: (1) A complete or incomplete specimen which serves as the base for the name of a taxon; (2) a single individual used to epitomize a sample.
typology: A scheme to order multiple types in relational manner. A common typology orders types in a hierarchical manner.
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