Archaeology & Evolution Glossary (L)

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


 
labial: Toward the lips, a direction on the anterior teeth toward the outside.

labial convexity: The degree of curvature in the mesial-distal direction of the labial surface of an incisor.

labiolingual: The breadth dimension of an incisor or canine, from the lip side to the tongue side.

lacrimal bone: In the skull, a small bone forming part of the medial orbit wall, between the maxilla and the ethmoid behind it.

lacrimal duct: Tear duct, connecting the orbit with the nasal cavity.

lacrimal foramen: Opening of the tear duct.

lacrimal fossa: Depression in which the lacrimal foramen sits.

lactation: Secretion of milk from mammary glands.

lacustrine: Deposits laid down in relatively still-water lakes, pertaining to a lake.

lagging strand: In DNA replication, the DNA strand that is synthesized discontinuously in the 5′ to 3′ direction away from the replication fork.

lambda: A point on the back of the skull at the juncture of the occiput and the parietal bones, where the sagittal and lambdoidal sutures meet.

lambdoidal flattening: A flattened surface at lambda, always extending anteriorly onto the parietal bones and in some cases extending posteriorly onto the occiput when a true occipital bun is formed.

lambdoidal suture: The transverse suture at the back of the cranium where the parietal and occipital bones join.

landscape archaeology: The study of individual features including settlements seen as single components within the broader perspective of the patterning of human activity over a wide area.

land-use pattern: The pattern found in the way the traces of hominid activities are distributed across the landscape.

larynx: The uppermost part of the windpipe, the sphincter guarding the entrance to the trachea and functioning as the sound-producing organ of the throat.

lateral: Away from the midline of the body.

lateral frontal trigone: A backward-facing triangular form to the lateral-most part of the supraorbital torus. The apex is created by a prominent temporal ridge, and the torus is thicker at the trigone than it is medially. To be distinguished from the frontal trigone.

lateralization: The transfer of a function to one side of a bilaterally symmetric structure or body.

lateral margins: Margins of detached pieces and objective pieces on either side of the longitudinal axis.

lava: Molten rock solidified on the Earth’s surface.

leader sequence: One of three main parts of the mRNA molecule. The leader sequence is located on the 5′ end of the mRNA molecule and contains the coded information that the ribosome and special proteins read to tell it where to begin the synthesis of the polypeptide.

leading strand: In DNA replication, the DNA strand synthesized continuously in the 5′ to 3′ direction toward the replication fork.

leptonema: The stage during meiosis in prophase I at which the chromosomes have begun to coil and are visible.

lesser trochanter: Large blunt process on the posterior face of the femoral shaft, just below the neck, for attachment of muscles that flex the thigh.

lethal allele: An allele that results in the death of an organism.

Levallois technique: A technique for flake production in which a stone core is shaped like a tortoise shell and a single flake with preformed shape is struck from it.

Levallois flakes: A flake struck from a Levallois core.

Levallois points: A point made from a Levallois flake.

lexicon: The collection of words in a language.

lexicostatistics: The study of linguistic divergence between two languages, based on changes in a list of common vocabulary terms and the sharing of common root words.

life history: The stages of life an organism passes through from birth to death.

ligament: A strong band of connective tissue linking two bones in a joint.

light repair: See photoreactivation.

limbic system: A complex part of the brain comprised of deep nuclei and fiber tracts related to the control and expression of the emotions.

limiting resources: Environmental factors whose abundance in a given habitat limits population size.

linea (line): A raised surface in the form of a narrow crest or ridge.

linea aspera: The elevated line that extends down the posterior surface of the femoral shaft.

lineage: A group of ancestral-descendant species that are reproductively isolated from other lineages, a line of common descent.

LINES (long interspersed repeated sequences): The dispersed families of repeated sequences in mammals that are several thousand base pairs in length and occur >20,000 times in the genome.

lingual: Toward the tongue, the tongue-facing side of a tooth.

linkage: A term describing genes located on the same chromosome.

linkage map: See genetic map.

linked genes: Genes that are located on the same chromosome.

linker: See restriction site linker.

lip: A projection found on the proximal ventral surface of a detached piece below the striking platform. Some researchers believe that a pronounced lip indicates the detached piece was removed with a soft hammer.

lithic: Of or pertaining to stone.

living floor: A preserved campsite.

load: Refers to the amount of force placed on the objective piece from either percussion or pressure. Load is generally increased when going from pressure flaking to percussion flaking and from soft hammer to hard hammer. The application of a force.

locus: A specific location (1) on a chromosome, matched to the corresponding position on the other chromosome of a pair, the site of the maternal and paternal alleles that are often considered together as a gene; (2) defined within a paleontological or archaeological site.

lod score method: The lod (logarithm of odds) score method is a statistical analysis, usually performed by computer programs, based on data from pedigrees. It is used to test for linkage between two loci in humans.

loess: A fine-grained deposit of wind-blown material.

longitudinal study: Examination of changes in individuals over a given time span.

loph: A crest or ridge of enamel on the occlusal surface of a tooth.

lordosis: Ventrally convex curvature of the spine, contrasting with the normally concave condition.

LSA: Late Stone Age.

lumbar: Pertaining to the lower back, the vertebrae that lie between the thoracic vertebrae and the sacrum.

lumper: One who emphasizes similarities and formalizes variation at higher taxonomic levels (cf. splitter).

lyonization: A mechanism in mammals that allows them to compensate for X chromosomes in excess of the normal complement. The excess X chromosomes are cytologically condensed and inactivated, and they do not play a role in much of the development of the individual. The name derives from the discoverer of the phenomenon, Mary Lyon.

lysogenic: A term describing a bacterium that contains a temperate phage in the prophage state. The bacterium is said to be lysogenic for that phage. On induction phage reproduction is initiated, progeny phages are produced, and the bacterial cell lyses.

lysogenic pathway: A path, besides the lytic cycle, that a phage can follow. The chromosome does not replicate; instead, it inserts itself physically into a specific region of the host cell’s chromosome in a way that is essentially the same as F factor integration.

lysogeny: The phenomenon of the insertion of a temperate phage chromosome into a bacterial chromosome, where it replicates when the bacterial chromosome replicates. In this state the phage genome is repressed and is said to be in the prophage state.

lytic cycle: A type of phage life cycle in which the phage takes over the bacterium and directs its growth and reproductive activities to express the phage’s genes and to produce progeny phages.

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.