Glossary – R


race (sociology): a human population unified by culture; more particularly, of related breeding stock; alternately, a subspecies that may interbreed with other subspecies.

racer snake (aka Galápagos racer, Pseudalsophis biserialis or Philodryas biserialis): a colubrid snake endemic to the Galápagos Islands.

rachis: an axial structure.

racoon: a medium-sized mammal native to North America. The most distinctive traits of the racoon are its dexterous front paws and its facial mask, which featured in the mythologies of native American tribes.

radar: an object-detection system employing radio waves.

radial glia cell: a glia stem cell in the central nervous system that serves as the progenitor to astrocytes, oligodendrocytes, and neurons.

radiant energy: the energy of electromagnetic and gravitational radiation.

radiation (evolutionary biology): profuse adaptive speciation.

radiation (physics): a process of traveling electromagnetic waves; also used for a similar sojourn of subatomic particles.

radiative zone (cosmology): the middle of 3 layers in a star’s interior, where core-produced radiation skitters about before eventually being emitted through the upper layer as light and heat.

radical (chemistry): a reactive atom, molecule, or ion owing to an unpaired valence electron. See polyatomic.

radical (mathematics): the square root of a number.

radical behaviorism: a school of behaviorism founded by B.F. Skinner which decreed that all behavior was a deterministic physiological reaction which may be conditioned.

Radical Reformation: a Protestant movement in the 16th century, reacting against the perceived corruption in the Catholic Church and the Magisterial Protestant movement led by Martin Luther and others. Magisterial Protestants essentially wanted to substitute their elite for those in the Catholic Church. Radical Reformists rejected this institutionalized authority in favor of egalitarianism. Most of the Radical Reformers were Anabaptists.

radical sign: √.

radicalism (politics): belief in extreme views or principles. Compare liberalism, conservatism, reactionism.

radicand: the number (x) of a radical (x).

radicle: the embryonic root of a plant, which is the first part of a seedling to emerge during germination and grow into the ground. The plumule is the baby shoot bearing leaves that grows after the radicle.

Radio Electronics (1929–2003): an American electronics magazine.

radio wave: a long wavelength electromagnetic radiation, ranging between 1 millimeter to 100 kilometers.

radioactivity: a subatomic process of losing energy.

radiology: imaging of organic substances using electromagnetic radiation.

radiolysis: radioactive molecular decay.

radioresistant: ionizing radiation resistant.

radish (Raphanus sativus): an edible root vegetable.

radium (Ra): the element with atomic number 88; a highly radioactive luminescent metal that glows a faint blue.

radon (Rn): the element with atomic number 86; a radioactive, colorless, tasteless, odorless noble gas.

Raffles’ pitcher plant (Nepenthes rafflesiana): a tropical pitcher plant native to Borneo, Sumatra, peninsular Malaysia, and Singapore, with at least 3 distinct varieties; named after Stamford Raffles.

raft spider (aka fishing spider, Dolomedes fimbriatus): a dark-bodied spider with a conspicuous light stripe that walks on water. Raft spiders run down their prey on water. They can submerge altogether to hide from predators.

ragworm: a marine annelid in the Platynereis genus.

ragworm (Hediste diversicolor): a polychaete (segmented) worm that lives in burrows at beaches and estuaries on the northeast Atlantic coast. A ragworm may grow to 10 cm. Ragworms practice agriculture in their burrows.

rail: a small to medium-sized bird in the large cosmopolitan Rallidae family. Rails live on every continent except Antarctica. Rails have short, rounded wings. Rail flight is not powerful, but they can stay aloft for prolonged periods. For lack of power, rails are easily blown off course, and thereby are common vagrants. This has resulted in rails colonizing many oceanic islands.

ramet (botany): an individual in a clonal population.

ramind: the logic processing (rational reasoning) part of the mind. Compare demind, inmind.

ramshorn snail: a freshwater snail in the Planorbidae family. The common name refers to the planispiral (coiled) shells that the snails have.

rancidity (aka rancidification): chemical decomposition of lipids. Rancidification has 3 pathways: hydrolytic, oxidative, and microbial. Hydrolytic rancidity happens when water peels fatty acid chains off the glycerol backbone in triglycerides. Oxidative rancidity transpires by free radicals on the loose (unbounded oxygen running rampant)–double-bonded unsaturated fats are cleaved, releasing volatile aldehydes and ketones. Microbial rancidity comes with the little ones employing their enzymes to fractionalize fat.

Randall–Sundrum model: a braneworld model that construes a universe of 5 dimensions using warped geometry, with the force of gravity (via gravitons) emanating from the 5th dimension, which is not compact (and so, invisible for being beyond Planck-unit measure); instead, merely phase-shifted from 3D space. There are 2 Randall–Sundrum models: RS1 and RS2. RS1 has 2 branes, while RS2 has 1 brane.

random (adjective): the idea that a system lacks order.

random competence: the faculty of an individual who can generally accomplish a routine task, but struggles, and is prone to blunder, with tasks which require on-the-spot problem-solving. Contrast random incompetence.

random incompetence: the faculty of an individual who is generally competent (satisfactory in task completion) in being a decent, spontaneous problem-solver, nonetheless exhibiting the occasional mistake. Contrast random competence.

random mutation (evolutionary biology): the absurd notion that evolution proceeds via random genetic mutations.

random sample (aka simple random sample): randomly picked sample objects for examination.

rangeomorph: a taxon of Ediacaran sessile frondose biota which grew to 2 meters and reproductively spread via propagule.

raptor (aka bird of prey): a carnivorous bird.

rare-male effect (aka negative frequency-dependent selection): the process in which the evolutionary fitness of a trait goes up as its relative abundance goes down.

raspberry: the delicate fruit of a multitude of flowering plants species in the rose family genus Rubus.

rat: a medium-sized, long-tailed rodent with superior cunning.

rate-of-living hypothesis: a 1908 hypothesis by Max Rubner that lifespan varies inversely with basal metabolic rate.

ratel: see honey badger.

rational (psychology): agreeable to reason, good sense, and sound judgment.

rationalism: the philosophic belief that reason is the source and arbiter of knowledge.

“All our knowledge begins with the senses, proceeds then to the understanding, and ends with reason. There is nothing higher than reason.” ~ Immanuel Kant

rational number: a number that can be expressed exactly by a ratio of 2 integers. Contrast irrational number.

rational therapy (aka rational emotive behavior therapy): a psychotherapy developed by Albert Ellis in the mid-1950s aimed at helping people be happier and thereby lead more fulfilling lives by discarding irrational thoughts that invoke negative emotions or maladaptive behavior.

rationalism: the epistemology that knowledge is attained deductively; an epistemology that regards reason as the source and test of knowledge. Rationalists believe that reality has an intrinsically logical structure. Hence, rationalists contend certain truths exist and the intellect can directly grasp these truths.

rationalization (psychology): to invent a sophistic explanation for acts, opinions, emotions, et cetera, that is not the actual cause or reason.

rationalization (sociology): setting aside human natural human inclinations toward emotional values and social mores for stark efficiency in meeting goals.

ratite: a diverse group of flightless birds.

rattlesnake: a venomous snake with a rattle at the end of its tail. Rattlesnakes kill by bite rather than constriction. 32 species are known.

raven: a relatively large corvid endemic to the northern hemisphere. The common raven is the largest perching bird.

ray (zoology): a flat-bodied, cartilaginous, marine fish closely related to sharks.

ray spider: a spider of ~30 species which constructs a cone-shaped web.

ray-finned fish (Actinopterygii): a class of bony fishes, comprising nearly 99% of fish species, over 30,000 species; so-called because their fins are webs of skin between bony spines (rays), as contrasted to fleshy, lobed fins (lobe-finned fish).

reaction formation: a Freudian defense mechanism in which unacceptable or anxiety-producing emotions and urges are overcome by embracing the opposite tendency.

reactionism (aka reactionaryism, reactionarism) (politics): belief in extremely conservative views or principles; favoring regressive change and opposing progressive change.

reactive oxygen species (ROS): chemically reactive molecules containing oxygen.

reactivity: the tendency to react from deep-seated emotion, particularly fear.

real: that which is, as contrasted to what manifests. See truth .

real number: either an integer, rational, irrational, algebraic, or transcendental number.

reality: that which necessarily is, phenomenal or noumenonal. Contrast actuality.

realization (aka unity consciousness): an enlightened state of consciousness with an abiding experience of the unicity of Nature. (Note that the term enlightenment is sometimes used for realization. No knowledgeable distinction may be made between enlightenment and realization by those not having attained unity consciousness.) Compare enlightenment, coherence consciousness.

reasoning: making sense of experience and applying logic.

reception: perception of a communication signal.

receptor (cytology): a cell signal receiver; a specific area on a cell, typically on its surface, with 1 or more proteins which are either receptive to stimulus, or which are identifying something contacting it; the term is also used as a misnomer by virologists for the cell binding site that viruses favor.

recession (economics): a general slowdown in economic activity. Compare stagflation, depression.

recessive (trait): a genetic trait (allele) that is masked by a dominant trait. Recessive traits are part of the phenotype only with homozygous alleles that are recessive.

reciprocal altruism: tit-for-tat altruism; an organism helping another with the expectation that the favor may be returned in the future.

reciprocity: mutual exchange (giving and receiving).

recoding (genetics): interpretive reading of genetic code by an organism.

recombination (genetics): mixing traits during meiosis that introduces diversity in offspring.

Reconstruction Era (1865–1877): the political period in the United States of policies designed to engender reintegration of the southern states back into civil union with the North. Most historians consider the endeavor a failure: the south remained an agricultural, poverty-stricken backwater, where whites reestablished dominance over blacks via violence and Jim Crow laws.

rectrix (plural: rectrices): one of the stiff main feathers of a bird’s tail, used to control the direction of flight.

rectum: the final straight portion of the large intestine in some mammals.

recursion (programming languages): the ability of a behavior to iteratively call itself.

red blood cell (aka erythrocyte): the most common type of vertebrate blood cell, employed to deliver oxygen to the tissues via blood flow through the circulatory system.

red colobus: a primarily arboreal Old World monkey native to western, central, and eastern Africa that lives in humid forests. Red colobuses live in groups of up to 80 members, albeit averaging 20–40, with twice as many females as males in a group. Groups establish dominance hierarchies via aggressive behavior. Red colobus monkeys are frequently hunted by chimps.

red deer: the 4th largest deer species (behind the moose, wapiti, and sambar deer); resident in Europe, western and central Asia.

red giant: a luminous giant star of relatively low mass.

red junglefowl (Gallus gallus): a tropical bird in the Phasianidae family, native to India, Southeast Asia, Indonesia, and nearby islands.

Red Queen hypothesis: an evolutionary hypothesis positing organisms’ need for constant adaptation to meet ever-changing environmental demands.

red-eyed vireo (Vireo olivaceus): a small American songbird.

red-tailed hawk (aka chicken hawk (though it rarely preys on chickens), Buteo jamaicensis): a bird of prey endemic to North America.

red-toothed shrew (aka long-tailed shrew): a common shrew in the genus Sorex with over 140 species, native to Eurasia and North America.

redback spider (Latrodectus hasseltii): a nocturnal, venomous spider indigenous to Australia.

redbelly snake (Storeria occipitomaculata): a nonvenomous snake endemic to eastern North America that may play dead when distressed.

redd: the nests of a female fish.

redox: a change during a reaction specific to loss or gain of electrons, with reduction a gain and oxidation a loss.

redshift: reflected light from a distant object, where the light has a longer wavelength. The longest human-visible wavelength of light is seen as reddish, hence the term redshift.

reductant: a chemical species that donates an electron to another species.

reduction (chemistry): a gain of electrons or a decrease in oxidation state to an atom or molecule; typically, reaction with hydrogen. Contrast oxidation.

reduction potential: the tendency of a chemical species to acquire electrons, and thereby be reduced.

reductionism: the absurd idea that a complex dynamic system can be understood by ascertaining and analyzing constituent elements. Reductionism requires that the something can never be more than the sum of its parts. Reductionists explain biological processes in the same way that chemists and physicists interpret inanimate matter. In adhering to empirical cause-and-effect, reductionism is a tool of matterism. See synergy. Contrast holism.

reef: a rock or other structure underwater.

reference frame (aka frame of reference): an abstract coordinate system that encompasses location, orientation, and measurement.

reference-group: a group that serves for self-evaluation. See in-group, out-group.

reflection (physics): a change in direction for an energy wavefront between 2 different media so that the wavefront returns into the medium from which it originated. Contrast refraction.

reflection (psychology): contemplation involving imagination.

reflex (biology): an autonomic response to a certain stimulus.

Reformation (aka Protestant Reformation) (16th century): a Christian reform movement that spawned the schism between Catholicism and Protestantism.

refraction: energy wave deflection due to passing from one medium into another, each medium having a distinct velocity. Contrast reflection (physics).

refractive index (aka index of refraction): a dimensionless number indicating the speed of light through a specific material. For instance, the refractive index of water is 1.333: light slows 1/3rd while traversing water (rather than vacuum). The refractive index determines by how much a light path is bent (refracted) when entering a certain material.

regression (biosphere): sea-level lowering. Contrast transgression.

regression (psychology): a Freudian defense mechanism involving a reversion of the ego to an earlier stage of development, rather than dealing with unacceptable desires in a more adult way.

regret: to be distressed over one’s past act or failure to act.

reify, reification: to regard an abstraction as an actual thing.

reincarnation: the idea that souls cycle through incarnations; common in many spiritual belief systems, though not a mainstream belief in Abrahamic religions (monotheistic religions which include Judaism, Christianity, and Islam).

reindeer (aka caribou in North America): a deer of the Arctic and Subarctic, resident in tundra and taiga biomes.

reionization: an epoch where the universe’s atomic matter reverted into ionized plasma.

reishi: a medicinal mushroom in traditional Chinese medicine.

relative permittivity (historically, dielectric constant): the relative resistance of a material to an electric field.

relativity (physics): the idea that there is an inertial reference frame. See general relativity, special relativity.

relativity of simultaneity: the idea that simultaneity is not absolute, instead depending upon an observer’s frame of reference. Different observers in relative motion to one another may legitimately disagree as to whether 2 events occurred simultaneously or one before the other.

reliability: the probability of success in light of the frequency of failure.

reliability theory: a probabilistic approach to engineering quality control that emphasizes dependability in product lifecycle management.

religion: a shared belief system encompassing the nature of the universe and life, commonly belied by evidence. Religions are frequently faith-based, typically dogmatic, and usually involve supernatural agents (gods). Compare natural philosophy. Contrast science.

reminiscence theory of knowledge: a hypothesis by Plato that all knowledge is attained by soul-searching; that all knowledge is innate and can only be tapped through introspection.

remote viewing: long distance visual perception. Compare out-of-body experience.

Renaissance (14th–17th centuries): the European intellectual and cultural movement from the mid-14th century (after the Black Death) into the 17th century, characterized by collective nostalgia for classical antiquity, though it ended up with skepticism toward traditional thought. The Renaissance affected the arts, religion, politics, philosophy, and science.

Renault (1899–): French automaker.

renascent: rising again into being or vigor.

renormalization: a mathematical technique to eradicate infinities from physics equations. As infinity is infinitely unwelcome, the erasure of renormalization is liberally applied as needed. Renormalization was initially viewed with suspicion, considered a provisional procedure, but eventually embraced as an acceptable adjunct. The use of renormalization illustrates the travesty of the physical models used in modern physics, which often provide elegant approximations at the expense of ignoring issues that infinities imply.

rent (economics): excess profit from economic power.

renewable: something which doesn’t wear out or go away.

reovirus: a virus of at least 87 species among 30 genera in the Reoviridae family, with a genome of double-stranded RNA and multi-layered capsids.

reptile: a clade of ectothermic, tetrapod, amniote vertebrates that is neither bird nor mammal. The earliest reptiles evolved over 315 MYA from amphibians that were adapting to aridity.

representative democracy: a form of democracy where citizens elect representatives to decide government policies. Compare direct democracy.

representativeness heuristic: a mental shortcut for judgment using probabilistic assumption based upon experience.

repression (psychology): a Freudian defense mechanism of excluding unacceptable desires from the conscious mind.

reprogramming (epigenetics): erasure and remodeling of epigenetic marks. Reprogramming is common during animal early development. Methylation is one reprogramming technique.

republic: a state which reflects the will of its citizenry.

Republican Party: the dominant conservative-reactionary party in the US. Contrast Democratic Party.

republicanism: the ideology of governing a state or society as a republic, where citizens hold popular sovereignty.

repulsion (psychology): strong dislike, distaste, aversion. Contrast attachment.

resistance (physics, chemistry): a measure of a material’s opposition to the flow of electric current; alternately, a measure of the force required to make a current flow through a material; measured in ohms.

resistant starch: starch that escapes digestion in the small intestines; a form of roughage (dietary fiber).

resistor (chemistry): a material that resists to a measurable degree passage of electric charges.

Resolution Trust Corporation (RTC) (1989–1995): a US government-owned corporation run by William Seidman, tasked with liquidating assets of failed thrifts during the 1980s–1990s savings and loan crisis.

resonance (music): the vibrational quality of a tone.

resonance (physics): a periodic synchrony.

reserpine (C33H40N2O9): an alkaloid derived from the root of the Indian snakeroot; a traditional Indian medicine for insanity, fever, and snakebite.

resolving power: the ability to perceive detailed images.

respiration (cellular): the metabolic processes and reactions that convert nutrients into ATP, with waste products released.

restriction factor: a protein in a cell that interferes with viral replication.

resveratrol (C14H12O3): a phenol produced by plants when attacked by bacteria or fungi; found in the skin of red grapes. Contrary to the ballyhoo, there is little evidence that resveratrol has a health benefit to humans.

retina: the light-sensitive layer of tissue lining the inner surface of the eye.

retinal (aka retinaldehyde, vitamin A aldehyde): one of many forms of vitamin A. Retinal binds to the protein opsin, which is the chemical basis of animal vision.

retinal bipolar cell: an intermediary type of nerve cell between photoreceptors (rod and cone cells) and ganglion cells. The human eye has 13 distinct types of bipolar cells.

retinal ganglion cell: a type of nerve cell near the inner surface of the retina that receives visual information from photoreceptors.

retinoblastoma: an aggressive cancer that attacks the retinas.

retinoic acid: a metabolite of vitamin A that mediates the functions of vitamin A required for growth and development. Chordate animals need retinoic acid.

retroreflection: radiation reflection back to its source with minimal scattering.

retrotransposon: (aka transposon via RNA intermediates): a genetic element that can amplify itself in a genome. Retrotransposons are considered a subclass of transposons.

retrovirus: a family of single-stranded RNA-enveloped viruses that replicate in a host cell via reverse transcription.

retrospective memory: a memory from the past. A retrospective memory may be explicit (declarative) or implicit (procedural). Contrast prospective memory.

return on equity (RoE): the rate of return for ownership interest (shareholder equity).

return on investment (ROI): the concept of an investment in a resource yielding a benefit to its investor.

Reverse Plaza Accord: a 1995 agreement among the United States, Germany, and Japan to reverse the 1985 Plaza Accord and strengthen the dollar against the yen and Deutsch mark.

reverse transcriptase: a DNA enzyme that transcribes single-stranded RNA into single-stranded DNA.

reverse transcription: the process of creating a single-stranded DNA from an RNA template using reverse transcriptase.

reversion evolution (aka reverse evolution, re-evolution, de-evolution, devolution, backward evolution): evolutionary descent with an unmanifest ancestral trait reactivated (atavism).

rhabdomeric (aka r-opsin): the type of photoreceptor used by protostomes (e.g., insects) for vision. Compare ciliary.

rheid (geology): a solid deformed by viscous flow. A solid becomes a rheid by sustained observation (that is, experiencing its deformation). The term was coined by Warren Carey in 1953. Contrast fluid.

rheid: a nominal solid at a temperature below melting point, deformed by viscous flow.

rheology: the geological science of matter flow.

rhesus macaque (Macaca mulatta): a mid-sized Old World monkey, native to south, central, and Southeast Asia; inhabiting a great variety of habitats, from grasslands to arid and forested biomes. Rhesus macaques are avid swimmers, which is rhizobacterium: a plant-beneficial soil bacterium.

rhizobia: soil bacteria of several species that cooperatively provide nitrogen fixation services for legumes. Rhizobia cannot by themselves fix nitrogen.

rhizoid: a specialized root-like tissue.

rhizome: a creeping rootstalk (underground stem shoot(s)) of a cloning plant.

Rhizopus: a genus of mold fungi.

rhizosphere: soil managed by plant roots via secretions. By contrast, bulk soil is outside the rhizosphere.

rhododendron: a genus of over 1,000 species of woody plants in the heath family. Most rhododendrons have showy flowers.

Rhodopseudomonas palustris: a common, waterborne, purple bacterium that can switch between different modes of metabolism.

rhodopsin (aka visual purple): a pigment-containing light-sensitive protein that converts light into an electrical signal (phototransduction).

rhubarb (Rheum rhabarbarum): an herbaceous perennial growing from short, thick rhizomes. Whereas the large leaves are poisonous, the long fleshy stalks are edible. Rhubarb has been used medicinally by the Chinese for thousands of years. By contrast, eating the stalks as food was first documented in 17th century England.

rhythm: the percussive propulsion of music. Compare melody.

ribbon synapse: a type of nerve synapse with promotes rapid signal transmission via a calcium channel.

ribonucleoprotein (RNP): an RNA-binding protein and associated RNA. RNPs work as regulators in RNA metabolism, DNA replication, and gene expression.

ribose (C5H10O5): a simple sugar (monosaccharide), finding equilibrium in 5 forms.

ribosome: the cellular factory for synthesizing proteins from peptide pieces.

ribozyme: an RNA-based enzyme.

rice: the edible seed of plant in the Oryza genus.

rickettsia: a genus of obligate intracellular bacteria parasites. Rickettsia depend the cytoplasm of a eukaryotic host cell for growth and replication. Rickettsia are known to infect protists, leeches, arthropods, and humans.

Riemannian geometry (aka elliptic geometry): a non-Euclidean geometry by Bernhard Riemann, rejecting Euclid’s 5th postulate (the parallel postulate) and modifying Euclid’s 2nd postulate (that finite straight lines can be extended) to state that all straight lines are the same length.

rift (geology): a chasm where crust and lithosphere are pulled apart.

Rig Veda (~1500–1200 BCE): an Indo-Aryan collection of 1,028 hymns and 10,600 verses in Sanskrit; 1 of the 4 canonical Vedas which form the basis of Hinduism. The other Vedas are Athar, Sama, and Yajur.

right triangle: a triangle with 2 sides forming a 90° angle.

right wing: the political philosophy that certain stratified social orders are natural, desirable, or inevitable; typically associated with conservatism and socioeconomic inequality. Contrast left wing.

Ring of Fire: a 1963 Johnny Cash song: “love is a burning thing, and it makes a fiery ring.” Perhaps you intended the Pacific Ring of Fire.

rinkhal (aka ringhal, ring-necked spitting cobra, Hemachatus haemachatus): a venomous, ovoviviparous, spitting snake of southern Africa. Not a true cobra, though it looks like one, but closely related.

riparian: the bank of a natural watercourse, such as a stream, river, or lake.

risk: the idea that loss or other inconvenience may occur.

risk sensitivity: the capability of an organism to discriminate between stable and unstable environments.

role (sociology): the behaviors, obligations, and privileges attached to a social status.

role (sociology): the behaviors, obligations, and privileges attached to a social status.

risk sensitivity: the capability of an organism to discriminate between stable and unstable environments.

river: a natural watercourse, usually freshwater, that flows to a lake, sea, or ocean.

rpm: revolutions per minute.

RNA (ribonucleic acid (C5H10O5)): a macromolecule comprising a long chain of nucleotides. RNA & DNA differ by their sugar (ribose versus deoxyribose (a ribose lacking an oxygen atom)). RNA & DNA also differ by 1 nucleobase: whereas RNA uses uracil (U), DNA employs thymine (T). See DNA.

RNA interference (RNAi): an epigenetic regulator of gene expression. RNAi limits gene expression. See miRNA.

RNA polymerase: an enzyme that unwinds a specific strand of DNA.

RNA splicing: editing precursor messenger RNA (mRNA) after transcription but before translation.

RNA world (abiogenesis): the hypothesis that life began with RNA-based replication.

roadrunner (aka chaparral bird): a fast-running ground cuckoo with a long tail and crest, endemic to the deserts of the southwestern United States and Mexico, in the genus Geococcyx, with 15 species.

Roaring Twenties: the economic prosperity during the 1920s of the industrialized countries in North America and Western Europe, particularly in major cities.

robber baron: beginning in the 1870s, a term applied to 19th-century American business magnates who engaged in unethical and monopolistic practices, wielded widespread political influence, and amassed enormous wealth. The term originally referred to noblemen in the Middle Ages who functioned as feudal warlords and were literally robber barons. Notable examples of American robber barons include Cornelius Vanderbilt (railroads and shipping), Andrew Carnegie (steel), J.P. Morgan (financier), John D. Rockefeller (oil), and Bill Gates (software). The clever rascals all redeemed their reputations for posterity by becoming philanthropists in their later years.

robber fly (aka assassin fly): a fast, medium-to-large, powerfully built, bristly fly in the Asilidae family (in the order Diptera, the true flies), with 7,000 described species. Robber flies are notoriously aggressive predators; hence the name. They prey on other insects as ambush hunters. Some robber flies resemble bumblebees, which these flies attack. Their disguise abets predation in affording close proximity before moving in for the kill.

robin: a common name for a passerine with a red or orange breast. The European robin (Erithacus rubecula) and American robin (Turdus migratorius), which are not closely related, are exemplary robins. The European robin is an Old World flycatcher. The American robin is a thrush.

robot: a computerized device with sensory faculty and capable of independent activity.

robotics: the application of computer technology to mechanical devices, typically for industrial and commercial activities.

rock ant (Temnothorax albipennis): a small European ant that builds simple nests in rock crevices using tiny pebbles and grains of sand.

rockrose: a small family of flowering plants endemic to the temperate areas of Europe and the Mediterranean basin, as well as North America, with a few species in South America.

rockcress: a small flowering plant in the Arabidopsis genus, related to mustard and cabbage. There are 9 rockcress species.

rod (cell): a black-and-white photoreceptor in the mammalian eye that receives 1 photon at a time. 1 of the 2 types of the photoreceptor cells in the retina (the other being cone cells).

rodent: an order of mammals characterized by constantly growing incisors that must be kept short by gnawing. ~40% of mammal species are rodents: 2,227 known species.

Rodinia (1.1–0.8 bya): the supercontinent containing all of Earth’s landmass, centered at the equator. Rodinia began breaking up around 800 mya, ending the abysmal chill of the Cryogenian period.

roe (singular & plural): fish egg masses (clusters).

role (sociology): the behaviors, obligations, and privileges attached to a social status.

Roman Curia: the Roman Catholic Church’s administrative organ.

Roman Empire (27 BCE–395 (undivided)/476 (Western)/1453 (Eastern)): the ancient Roman civilization after the Republic. Theodosius I was the last Roman emperor to rule an undivided Empire. The Western Roman Empire fell when Romulus Augustulus was deposed by Flavius Odoacer in 476. The Eastern Roman (Byzantine) Empire crumbled into feudal kingdoms before finally falling to the onslaught of the Ottoman Turks in 1453. See Byzantine Empire.

Roman Kingdom (753–509 BCE): the monarchial period of ancient Rome, before the Roman Republic.

Roman Republic (509–27 BCE): the period of ancient Roman civilization that began with the overthrow of the Roman Kingdom and ended with the establishment of the Roman Empire under Octavian.

Romanesco broccoli: the flower bud of Brassica oleracea, notable for its fractal appearance, its relative crunchiness, and delicate, nutty flavor.

Romanov, House of (aka Romanoff) (1613–1917): the 2nd and last imperial dynasty that ruled Russia.

Romanticism (aka Romantic Era): the intellectual and aesthetic movement which originated in Europe at the end of the 18th century and was the strong intellectual current there until 1850. Romanticism emphasized the subjective emotions behind the aesthetic experiences of life. Romanticism revolted against the aristocratic norms of the day, as well as taking a swipe at the scientific rationalization of the natural world, in favor of admiring the beauty and power of Nature. Romanticism weaved a complex set of effects; politically, it fostered nationalism. See Age of Enlightenment.

Romans: the citizens of the ancient Roman Republic or Empire.

rook: the most abundant Eurasian corvid.

room temperature: 17–25 °C; an average of 23 °C.

rootless duckweed (aka spotless watermeal, Wolffia arrhiza): an aquatic plant; the smallest vascular plant in the world.

rorqual whale: the largest group of baleen whales, with 9 species, including the largest animal that has ever lived: the blue whale. Rorquals are slender and streamlined compared to their cousins, the right whales. Most roquals have narrow, elongated flippers. Rorquals have folds of skin that allow them to widely open their mouths for feeding, which they do by gulping in water, then pushing it out through their baleen plates with their tongue. Rorquals feed on crustaceans such as krill, but also on various small fish, including sardines and herring.

rose: a woody perennial, well known for gorgeous flowers.

rostrum: the snout or beak-like projection from the head of a dolphin or other vertebrate. The term rostrum is overloaded with similar meaning for invertebrate parts. The forward extension from the carapace (front section) of a crustacean is its rostrum. Mollusks have beak-like mouthparts which are referred to as a rostrum (or proboscis).

rotenone (C23H22O6) : an odorless, colorless, crystalline ketone, used as a broad-spectrum insecticide, pesticide, and piscicide (fish killer). Rotenone foils electron transport in mitochondria. Rotenone occurs naturally in the roots, seeds, and stems of several plants as a defense against herbivory.

rotifer: a phylum of tiny pseudocoelomate animals, common in freshwater, though there are a few marine rotifers; most are free-living, though ~25 species are colonial.

roundworm (aka nematode): a worm of an estimated 100,000 species in a diverse phylum. Over 28,000 species are known, of which 60% (over 16,000) are parasitic. Unlike earlier-evolved cnidarians (jelly-like marine animals) and flatworms, nematodes have tubular digestive systems, with openings at both ends. Compare flatworm.

roughage: dietary fiber.

rove beetle: a beetle in the largest family of beetles (Staphylinidae), which has a lineage back to the Triassic, 200+ mya.

Roxarsone: an organoarsenic compound used as a feed additive for poultry and pigs to increase weight gain.

royal jelly: a honeybee secretion fed to larvae and adult queens.

royalactin: the protein in royal jelly that engenders development of a queen via epigenetic modifications.

rubidium (Rb): the element with atomic number 37; a highly reactive, soft, silvery-white alkali metal. Rubidium 85Rb is the only stable isotope, and the most common (72%). 87Rb, which is 28% of naturally occurring rubidium, is slightly but persistently radioactive, with a half-life of 49 billion years.

ruin lizard (aka Italian wall lizard, Podarcis sicula): a lizard endemic to Europe, most abundant in southern Italy.

rule: a regulating principle.

rumen (aka paunch): the 1st chamber of the alimentary canal of ruminant animals. The rumen is the primary site for microbial fermentation of ingested food.

ruminant: an herbivorous mammal with a rumen.

Ruminococcus: a genus of anaerobic bacteria, found in abundance in the intestines of humans who eat a lot of polyunsaturated fats and/or often drink alcohol. See Bacteroides, Prevotella.

runaway hypothesis: a hypothesis that evolution by mating preference can lead to absurd extremes.

Russia: the world’s largest country (17.1 million km2), with 146 million people (2019); a late economic developer with a history of thuggish governance.

rutin (C27H30O16; aka rutoside, sophorin): a citrus flavonoid glycoside found in many plants. In humans, rutin acts as a blood thinner, improving circulation and preventing clotting. Rutin has anti-inflammatory effects. It increases thyroid iodide uptake. Rutin is a strong antioxidant.

rye (Secale cereale): a cereal grain closely related to barley and wheat.

Rwanda: an agrarian nation-state in central east Africa; a former German colony (1884–1962); one of the smallest countries on the African mainland (26,338 km2), with one of the highest population densities (11 million in 2015).