racemization: The conversion of some amino acids from their original "left-handed" form to "right-handed" form, after death, so that the two forms occur iin about equal numbers.

radial notch: Smooth facet on the ulna's proximal shaft where the head of the radius articulates during radial rotation.

radioactive decay: The regular process by which radioactive isotopes braek down into their decay products with a half-life which is specific to the isotope in question.

radiocarbon dating: An absolute dating method that measures the decay of the radioactive isotope of carbom (14C) in organic material.

radioimmunoassay: A method of protein analysis whereby it is possible to identify protein molecules surviving in fossils which are thousands and even millions of years old.

radiometric: A process based on nuclear decay, as in radiometric dating.

radius: One of two long bones of the forearm, on the thumb side, which rotates against the ulna so that its lower end, the hand, can be turned.

raised beaches: These are remnants of former coastlines, usually the result of processes such as isostatic uplift or tectonic movements.

ramage: A term used by Firth to denote a cognatic descent group, and by Sahlins to denote a descent system where local descent groups are ranked according to senoirity of descent.

ramus: The portion of bone at an angle to the body, as in ascending ramus (mandible), or pubic ramus (innominate).

random mating: Matings between genotypes occurring in proportion to the frequencies of the genotypes in the population.

range: Territory normally occupied.

ranked societies: Societies in which there is unequal access to prestige and status.

rDNA repeat units: The tandem arrays of rRNA genes, 18S-5.8S-28S, repeated many times along the chromosome.

recapitulation: The theory that "ontogeny recapitulates phylogeny."

recessive: An allele or phenotype that is expressed only in the homozygous state.

recessive lethal allele: An allele that causes lethality when it is homozygous.

reciprocal altruism: Exchange of favors by two individuals in which one individual temporarily sacrifices potential fitness in expectation of a return.

reciprocal cross: A cross of males and females of one trait with males and females of another trait. In the garden pea example, a reciprocal cross for smooth and wrinkled seeds is smooth female X wrinkled male and wrinkled female X smooth male.

recombinant chromosome: A chromosome that emerges from meiosis with a combination of genes different from a parental combination of genes.

recombinant DNA molecule: A new type of DNA sequence that has been constructed or engineered in the test tube from two or more distinct DNA sequences.

recombinant DNA technology: A collection of experimental procedures that allow molecular biologists to splice a DNA fragment from one organism into DNA from another organism and to clone the new recombinant DNA molecule. It includes the development and application of particular molecular techniques, such as biotechnology or genetic engineering. This technology is important, for example, in the production of antibiotics, hormones, and other medical agents used in the diagnosis and treatment of certain genetic diseases.

recombinants: The individuals or cells that have nonparental combinations of genes as a result of the processes of genetic recombination.

recombination: The bringing together of novel combinations of genes by the process of meiosis and crossover during sexual reproduction. See genetic recombination.

redistribution: A mode of exchange that implies the operation of some central organizing authority. Goods are recieved or appropriated by the central authority, and subsequently some of them are sent by that authority to other loactions.

refitting: Sometimes referred to as conjoining, this entails attempting to put stone tools and flakes back together again, and provides important information on the processes involved in the knapper's craft.

refutationist view: Approach which holds that science consists of theories about the empirical world, that its goal is to develop better theories, which is achieved by finding mistakes in existing theories, so that it is crucial that theories be falsifiable (vulnerable to error and open to testing). The approach, developed by Karl Popper, emphasizes the importance of testability as a component of scientific theories.

regional continuity: The observation that there is a sequence of anatomical features, often found together, spanning the time from earlier to later populations in a geographic region, that seems to reflect some degree of ancestral-descendent relationship.

regression: A statistical analysis assessing the association between two variables.

regression line: A mathematically computed line that represents the best fit of a line to the points.

regulated gene: A gene whose activity is controlled in response to the needs of a cell or organism.

regulatory factors: Proteins active in the activation or repression of transcription of the gene.

relationship systems: term used by Needham and other proponents of the "category" approach to kinship terms to denote "kinship" terminologies.

relative dating: Determination of the ordered sequence of sites, artifacts, or fossils.

release factors: See termination factors.

religion: A framework of beliefs relating to supernatural or superhuman beings or forces that transcend the everyday material world.

replica plating: The procedure for transferring the pattern of colonies from a master plate to a new plate. In this procedure, a velveteen pad on a cylinder is pressed lightly onto the surface of the master plate, thereby picking up a few cells from each colony to inoculate onto the new plate.

replication bubble: Opposing replication forks found with the local denaturing of DNA during replication.

replication fork: A Y-shaped structure formed when a double-stranded DNA molecule unwinds to expose the two single-stranded template strands for DNA replication.

replication machine (replisome): The complex formed by the close association of the key proteins used during DNA replication.

replicon (replication unit): The stretch of DNA in eukaryotes from the origin or replication to the two termini of replication on each side of the origin.

repressor: See repressor gene.

repressor gene: A regulatory gene whose product is a protein that controls the transcriptional activity of a particular operon.

repressor molecule: The protein product of a repressor gene.

repulsion: An arrangement in which each homologous chromsome carries the wild-type allele of one gene and the mutant allele of the other one.

residence rules: Conventions for residence by a couple after marriage, defining whether they reside with husband's kin, wife's kin, or others.

resorb: To destroy and remove bone or parts of bone by osteoclasts (bone cells with digestive enzymes).

restriction endonucleases (restriction enzymes): Enzymes important for analyzing DNA and for constructing recombinant DNA molecules because of their ability to cleave double-stranded DNA molecules at specific nucleotide pair sequences.

restriction enzymes: See restriction endonucleases.

restriction fragment length polymorphism (RLFPs): The different restriction maps that result from different patterns of distribution of restriction sites. They are detected by the presence of restriction fragments of different lengths on gels.

restriction map: A genetic map of DNA showing the relative positions of restriction enzyme cleavage sites.

restriction site linker: A relatively short, double-stranded oligodeoxyribonucleotide about 8 to 12 nucleotide pairs long that is synthesized by chemical means and that contains the cleavage site for a specific restriction enzyme within its sequence.

retouch: Intentional modification of a stone tool edge by either pressure or percussion flaking technique. Modification by use is considered usewear as opposed to retouch.

retract: Pull backwards.

retromolar space: A space or gap at the rear of a mandible between the back of the last molar and the anterior edge of the ascending ramus where it crosses the alveolar margin.

retrovirus: Single-stranded DNA virus that replicates via double-stranded DNA intermediates. The DNA integrates into the host's chromosome where it can be transcribed.

reversed polarity epoch: Period of geological time in which the earth's magnetic field is directly the opposite to what it is at present (the north end of a compass would point north, rather than south).

reverse genetics: See positional cloning.

reverse mutation (reversion): A mutational change from a mutant allele back to a wild-type allele.

reverse transcriptase: An enzyme (an RNA-dependent DNA polymerase) that makes a complementary DNA copy of an mRNA strand.

rhinarium: A hairless patch of skin between the nose and upper lip that is kept moist to enhance the sense of smell.

rhizotic: Rooted, a model of change in which elements (populations cultures, languages) are derived from or rooted in several different antecedents.

rhyolite: The fine-grained member of the granite family of igneouos rocks. It is light in color and usually contains pink feldspar.

ribonuclease (RNase): An enzyme that catalyzes the degradation of RNA to nucleotides.

ribonucleic acid (RNA): A usually single-stranded polymeric molecule consisting of ribonucleotide building blocks. RNA is chemically very similar to DNA. The three major types of RNA in cells are ribosomal RNA (rRNA), transfer RNA (tRNA), and messenger RNA (mRNA), each of which performs an essential role in protein synthesis (translation). In some viruses, RNA is the genetic material.

ribonucleotide: The basic building block of RNA consisting of a sugar (ribose), a base, and a phosphate.

ribose: The pentose sugar component of the nucleotide building block of RNA.

ribosomal DNA (rDNA): The regions of the DNA that contain the genes for the rRNAs in prokaryotes and eukaryotes.

ribosomal proteins: The proteins that along with rRNA molecules comprise the ribosomes of prokaryotes and eukaryotes.

ribosomal RNA (rRNA): The RNA molecules of discrete sizes that along with ribosomal proteins comprise ribosomes of prokaryotes and eukaryotes.

ribosome: A complex cellular particle composed of ribosomal protein and rRNA molecules that is the site of amino acid polymerization during protein synthesis.

ribosome-binding site: The nucleotide sequence on an mRNA molecule on which the ribosome becomes oriented in the correct reading frame for the initiation of protein synthesis.

ridge: A narrow roughened elevation on a bone's surface.

R looping (R loops): A technique developed by M. Thomas, R. White, and R. Davis in which molecules of double-stranded DNA are incubated at temperatures below their denaturing temperature to open up short stretches of the DNA double helix so that single-stranded RNA molecules can begin to form DNA/RNA hybrids where the two are complementary. The DNA/RNA hybrid forms an R loop by displacing a single-stranded section of DNA.

RNA: See ribonucleic acid.

RNA editing: Posttranscriptional insertion and/or deletion of nucleotides in an mRNA molecule.

RNA ligase: An enzyme that splices together the RNA pieces once the intervening sequence is removed from the pre-tRNA.

RNA polymerase: An enzyme that catalyzes the synthesis of RNA molecules from a DNA template in a process called trascription.

RNA polymerase I: An enzyme in eukaryotes located in the nucleolus that catalyzes the transcription of the 18S, 5.8S, and 28S rRNA genes.

RNA polymerase II: An enzyme in eukaryotes found only in the nucleoplasm of the nucleus. It catalyzes the transcription of mRNA-coding genes.

RNA polymerase III: An enzyme in eukaryotes found only in the nucleoplasm. It catalyzes the transcription of the rRNA and 5S rRNA genes.

RNA primer: A preexisting polynucleotide chain in DNA replication to which new nucleotides can be added.

RNA processing control: The second level of control of gene expression in eukaryotes. This level involves regulating the production of mature RNA molecules from precursor-RNA molecules.

RNA synthesis: See transcription.

Robertsonian translocation: A type of nonreciprocal translocation in which the long arms of two nonhomologous acrocentric chromosomes become attached to a single centromere.

robust: A large or heavily built body or body part.

Robusticity Index: An index obtained by expressing a diameter (or circumference) of a bone in terms of its length.

rock: Any naturally formed, firm and coherent aggregate or mass of mineral matter that constitutes part of the Earth's crest.

rock composition: Refers to the chemical elements and mineral from which rocks are created.

rock texture: Refers to the size, shape, and relationship of individual particles in a rock.

rock varnishes: Natural accretions of magnesium and iron oxides, togetehr with clay minerals and organic matter, which can provide valuable environmental evidence. Their study, when combined with radiocarbon methods, can provide a minimum age for some landforms, and even some types of stone tools which can accumulate varnish.

roll-out: See hinge termination.

Romer's Rule: The generalization that new adaptations are often allowed by evolutionary changes that initially better adapt a species to its old way of life