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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.
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