ice cores: Borings taken from the Arctic and Antarctic polar ice caps, containing layers of compacted ice useful for the reconstruction of paleoenvironments and as a method of absolute dating.
igneous rock: Rock formed as a result of the hardening of lava or magma (molten rock). Examples of igneous rock are obsidian, basalt, and rhyolite.
iliac pillar: A bony buttress extending vertically down the iliac blade, supporting it against the powerful muscular forces generated by the hip abductor muscles.
ilium (iliac blades): The side, or broad and flat blade of the innominate, forming its upper portion.
imaginal discs: In the Drosophila blastoderm, undifferentiated cells that will develop into adult tissue and organs.
immunoglobulins: Specialized proteins (antibodies) secreted by B cells that circulate in the blood and lymph and that are responsible for humoral immune responses.
inbreeding: Preferential mating between close relatives.
Inca bone: A triangular shaped Wormian bone found where the lambdoidal suture meets the sagittal suture.
incisiform: Shaped like an incisor.
incisive canal: Tubular passageway between the anterior portion of the hard palate and the floor of the nose, to carry the nerves and vessels running between the nasal and oral cavities.
incisive foramen: Opening of the incisive canal onto the roof of the hard palate, located just behind (and above) the roots for the central incisors.
incisor: Broad tooth at the front-most part of the jaw.
inclusive fitness: A characterization of how well a feature’s genetic material is represented in the next generation because of the survival of the group of those relatives who share it.
incomplete (partial) dominance: The condition resulting when one allele is not completely dominant to another allele so that the heterozygote has a phenotype between that shown in individuals homozygous for either individual allele involved. An example of partial dominance is the frizzle chicken.
induced mutation: A mutation that results from treatment with mutagens.
inducer: A chemical or environmental agent for bacterial operons that brings about the transcription of an operon.
induction: The synthesis of a gene product (or products) in response to the action of an inducer, that is, a chemical or environmental agent.
inductively coupled plasma emission spectrometry (ICPS): Based on the same basic principles as OES (optical emission spectrometry), but the generation of much higher temperatures reduces problems of interference and produces more accurate results.
industry: A group of archaeological assemblages found over a specific region or time whose artifacts are similar.
infanticide: The killing of infants.
informal tools: Stone tools made in a casual manner with only minor design constraints. These tools are often called expediently made tools or tools made for the need of the moment.
infraorbital foramen: An opening under the lower orbital rim for the infraorbital nerve and vessels.
infrared absorption spectrometry: A technique used in the characterization of raw materials, it has been particularly useful in distinguishing ambers from different sources: the organic compounds in the amber absorb different wavelengths of infrared radiation passed through them.
inion: The center of the tuberculum linearum, a protuberance of varying expression that develops where the superior nuchal lines meet at the sagittal plane. It is not necessarily what is called the external occipital protuberance (although this describes what it is) which occurs above it, at or below where the supreme nuchal lines meet at the midline.
innerorbital: Encompassing the orbits.
innervated: Served by the branches of one of the nerves.
innominate (os coxae): Large bone forming the sides of the pelvis.
insertion: The attachment of a muscle or ligament farthest from the trunk or center of the body.
insertion sequence (IS) element: The simplest transposable genetic element found in prokaryotes. It is a mobile segment of DNA that contains genes required for the process of insertion of the DNA segment into a chromosome and for the mobilization of the element to different locations.
interaction sphere: A regional or interregional exchange system, e.g., the Hopewell interaction sphere.
interaction variance (VI): Genetic variance that arises from epistatic interactions among genes.
intercostal muscles: Muscles situated between the ribs.
intergenic suppressor: A mutation whose effect is to suppress the phenotypic consequences of another mutation in a gene distinct from the gene in which the suppressor mutation is located.
interglacial: A warm period between two major periods of multiple glaciations.
internal buttress (of the mandible): Transverse torus or tori on the inside surface of the symphysis. When the most inferior one is the most posterior point on the internal surface, it is a simian shelf.
internal control region (ICR): Promotor sequence, recognized by RNA polymerase III, that is located within the gene sequence, for instance, in tRNA genes and 5S rRNA genes of eukaryotes.
internasal angle: The angle formed by the lengthwise joint of the two nasal bones, where they meet at the internasal suture.
internasal suture: The suture between the two nasal bones where they meet at the midline.
interorbital: Between the orbits.
interpluvial: A dry phase between two rainy periods.
interproximal facet: Wear surface between the vertical crown walls of two adjacent teeth, created by anterior forces and transverse motions during mastication.
interproximal wear: Tooth wear betwean adjacent teeth, on the adjacent (mesial and distal) sides.
interspecific allometry: The relationship between size and shape across a range of different species.
interstadial: A warmer interval between stadials within a major glaciation.
interstitial wear: See interproximal wear.
intervening sequence (ivs): See introns.
intra– Among or within.
intragenic suppressors: A mutation whose effect is to suppress the phenotypic consequences of another mutation within the same gene in which the suppressor mutation is located.
intraspecies clade: A group of ancestral-descendant poulations that share common descent (although not unique common descent) within a species.
intron: A nucleotide sequence in eukaryotes that must be excised from a structural gene transcript in order to convert the transcript into a mature messenger RNA molecule containing only coding sequences that can be translated into the amino acid sequence of a polypeptide.
inversion: 1) Turning inward, for example, of the sole of the foot 2) A chromosomal mutation that results when a segment of a chromosome is excised and then reintegrated in an orientation 180º from the original orientation.
ischial tuberosity: The roughened area at the base of the ischium for the hamstrings attachment.
ischium: The lower rear bone of the innominate.
IS element: See insertion sequence (IS) element.
isolating mechanisms: Biological or behavioral characteristics of individuals which prevent sympatric groups from interbreeding.
isometry: Change in overall size that maintains the same relative proportional shape.
isotope: Chemically identical but anatomically different forms of an element (the number of neutrons are different so the atomic weight differs).
isostatic uplift: Rise in the level of the land relative to the sea caused by the relaxation of Ice Age conditions. It occurs when the weight of ice is removed as temperatures rise, and the landscape is raised to form raised breaches.
isotopic analysis: An important source of information on the reconstruction of prehistoric diets, this technique analyses the ratios of the principle isotopes preserved in human bone; in effect the method reads the chemical signatures left in the body by different foods. Isotopic analysis is also used in characterization studies.
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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.