also rat race, 1934 in reference to aviation training, from rat (n.) + race (n.1).

A rat race is ... a simple game of "follow the leader" in fighter planes. The leader does everything he can think of — Immelmanns, loops, snap rolls, and turns, always turns, tighter and tighter. [Popular Science, May 1941]

In the 1930s actual rat races of some sort are frequently mentioned among popular carnival and gambling attractions. Meaning "fiercely competitive struggle," especially to maintain one's position in work or life is by 1939. Rat-run is from 1870 in the sense of "maze-like passages by which rats move about their territory," but originally and usually in a derogatory transferred sense.

[Matthew] Milton was not, at the period we write of [c. 1811], at all in the ring ; for in the following March he was steward of a rat-race, held at a public-house in Shepherd's-market, where four of these "varmin," decorated with different coloured ribands, were started for a sweepstakes, round the clubroom, before a host of sportsmen. ["Sporting Incidents at Home and Abroad," The Sporting Review, May 1848]

*rēd-, Proto-Indo-European root meaning "to scrape, scratch, gnaw."

It forms (possibly) all or part of: abrade; abrasion; corrode; corrosion; erase; erode; erosion; radula; rascal; rase; rash (n.) "eruption of small red spots on skin;" raster; rat; raze; razor; rodent; rostrum; tabula rasa.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit radati "scrapes, gnaws," radanah "tooth;" Latin rodere "to gnaw, eat away," radere "to scrape;" Welsh rhathu "scrape, polish."

*genə-, also *gen-, Proto-Indo-European root meaning "give birth, beget," with derivatives referring to procreation and familial and tribal groups.

It forms all or part of: Antigone; autogenous; benign; cognate; congener; congenial; congenital; connate; cosmogony; cryogenic; degenerate; engender; engine; epigone; eugenics; -gen; gendarme; gender; gene; genealogy; general; generate; generation; generic; generous; genesis; -genesis; genial; -genic; genital; genitive; genius; genocide; genotype; genre; gens; gent; genteel; gentile; gentle; gentry; genuine; genus; -geny; germ; german (adj.) "of the same parents or grandparents;" germane; germinal; germinate; germination; gingerly; gonad; gono-; gonorrhea; heterogeneous; homogeneous; homogenize; homogenous; impregnate; indigenous; ingenious; ingenuous; innate; jaunty; kermes; kin; kindergarten; kindred; king; kind (n.) "class, sort, variety;" kind (adj.) "friendly, deliberately doing good to others;" Kriss Kringle; malign; miscegenation; nada; naive; nascent; natal; Natalie; nation; native; nature; nee; neonate; Noel; oncogene; ontogeny; photogenic; phylogeny; pregnant (adj.1) "with child;" primogenitor; primogeniture; progenitor; progeny; puisne; puny; renaissance; theogony; wunderkind.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit janati "begets, bears," janah "offspring, child, person," janman- "birth, origin," jatah "born;" Avestan zizanenti "they bear;" Greek gignesthai "to become, happen," genos "race, kind," gonos "birth, offspring, stock;" Latin gignere "to beget," gnasci "to be born," genus (genitive generis) "race, stock, kind; family, birth, descent, origin," genius "procreative divinity, inborn tutelary spirit, innate quality," ingenium "inborn character," possibly germen "shoot, bud, embryo, germ;" Lithuanian gentis "kinsmen;" Gothic kuni "race;" Old English cennan "beget, create," gecynd "kind, nature, race;" Old High German kind "child;" Old Irish ro-genar "I was born;" Welsh geni "to be born;" Armenian cnanim "I bear, I am born."

*teutā-, Proto-Indo-European root meaning "tribe." It forms all or part of: Deutsch; Dutch; Plattdeutsch; Teuton; Teutonic.

It is the hypothetical source of/evidence for its existence is provided by: Old Irish tuoth "people," Old Lithuanian tauta "people," Old Prussian tauto "country," Oscan touto "community," German Deutsch, Gothic þiuda, Old English þeod "people, race, nation," Old English þeodisc "belonging to the people." But Boutkan says it is probably a substratum word.

*bheuə-, also *bheu-, Proto-Indo-European root meaning "to be, exist, grow."

It forms all or part of: Bauhaus; be; beam; Boer; bondage; boodle; boom (n.1) "long pole;" boor; booth; bound (adj.2) "ready to go;" bower; bowery; build; bumpkin; busk; bustle (v.) "be active;" byre; bylaw; Eisteddfod; Euphues; fiat; forebear; future; husband; imp; Monophysite; neighbor; neophyte; phyletic; phylo-; phylum; phylogeny; physic; physico-; physics; physio-; physique; -phyte; phyto-; symphysis.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit bhavah "becoming," bhavati "becomes, happens," bhumih "earth, world;" Greek phyein "to bring forth, make grow," phytos, phyton "a plant," physis "growth, nature," phylon "tribe, class, race," phyle "tribe, clan;" Old English beon "be, exist, come to be, become, happen;" Old Church Slavonic byti "be," Greek phu- "become," Old Irish bi'u "I am," Lithuanian būti "to be," Russian byt' "to be."

*sterə-, also *ster-, Proto-Indo-European root meaning "to spread."

It forms all or part of: consternate; consternation; construct; construction; destroy; destruction; industry; instruct; instruction; instrument; obstruct; obstruction; perestroika; prostrate; sternum; sternocleidomastoid; strain (n.2) "race, stock, line;" stratagem; strategy; strath; strato-; stratocracy; stratography; stratosphere; stratum; stratus; straw; stray; street; strew; stroma; structure; substrate; substratum; substructure.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit strnoti "strews, throws down;" Avestan star- "to spread out, stretch out;" Greek stronymi "strew," stroma "bedding, mattress," sternon "breast, breastbone;" Latin sternere "to stretch, extend;" Old Church Slavonic stira, streti "spread," strana "area, region, country;" Russian stroji "order;" Gothic straujan, Old High German strouwen, Old English streowian "to sprinkle, strew;" Old English streon "strain," streaw "straw, that which is scattered;" Old High German stirna "forehead," strala "arrow, lightning bolt;" Old Irish fo-sernaim "spread out," srath "a wide river valley;" Welsh srat "plain."