Evolution Julian Huxley

1 evolution

1.1 personal influence
1.2 evolutionary synthesis
1.3 evolutionary progress

evolution

huxley , biologist august weismann insisted on natural selection primary agent in evolution. huxley major player in mid-twentieth century modern evolutionary synthesis. prominent populariser of biological science public, focus on 3 aspects in particular.

personal influence

in 20th century 1 of minority of biologists believed natural selection main driving force of evolution, , evolution occurred small steps , not saltation (jumps). these opinions standard.

though time academic quite brief, taught , encouraged number of evolutionary biologists @ university of oxford in 1920s. charles elton (ecology), alister hardy (marine biology) , john baker (cytology) became highly successful, , baker wrote huxley s royal society obituary memoir.

perhaps significant edmund brisco ford, founded field of research called ecological genetics, played role in evolutionary synthesis. important disciple gavin de beer, wrote on evolution , development, , became director of natural history museum. both these fine scholars had attended huxley s lectures on genetics, experimental zoology (including embryology) , ethology. later, became collaborators, , leaders in own right.
in era when scientists did not travel today, huxley exception, travelled in europe, africa , united states. therefore able learn , influence other scientists, naturalists , administrators. in able meet other evolutionists @ critical time in reassessment of natural selection. in africa able influence colonial administrators education , wild-life conservation. in europe, through unesco, @ centre of post-world war ii revival of education. in russia, however, experiences mixed. favourable view changed growing awareness of stalin s murderous repression, , lysenko affair. there seems little evidence had effect on soviet union, , same said other western scientists.

marxist-leninism had become dogmatic religion… , dogmatic religions, had turned reform persecution.

evolutionary synthesis

huxley 1 of main architects of modern evolutionary synthesis took place around time of world war ii. synthesis of genetic , population ideas produced consensus reigned in biology 1940, , still broadly tenable.


informative episode in history of evolutionary biology establishment of neo-darwinian synthesis . berry , bradshaw, 1992. synthesis brought not 1 side being proved right , others wrong, exchange of viable components of competing research strategies . ernst mayr, 1980.


huxley s first trial run treatment of evolution in science of life (1929–30), , in 1936 published long , significant paper british association. in 1938 came 3 lengthy reviews on major evolutionary topics. 2 of these papers on subject of sexual selection, idea of darwin s standing has been revived in recent times. huxley thought sexual selection …merely aspect of natural selection which… concerned characters subserve mating, , sex-limited . rather grudging acceptance of sexual selection influenced studies on courtship of great crested grebe (and other birds pair life): courtship takes place after mate selection, not before.
now time huxley tackle subject of evolution @ full length, in became defining work of life. role of synthesiser, , helped had met many of other participants. book evolution: modern synthesis written whilst secretary zoological society, , made use of remarkable collection of reprints covering first part of century. published in 1942. reviews of book in learned journals little short of ecstatic; american naturalist called outstanding evolutionary treatise of decade, perhaps of century. approach thoroughly scientific; command of basic information amazing .
huxley s main co-respondents in modern evolutionary synthesis listed ernst mayr, theodosius dobzhansky, george gaylord simpson, bernhard rensch, ledyard stebbins , population geneticists j. b. s. haldane, ronald fisher , sewall wright.

however, @ time of huxley s book several of these had yet make distinctive contribution. certainly, huxley, e. b. ford , co-workers in ecological genetics @ least important; , cyril darlington, chromosome expert, notable source of facts , ideas.

an analysis of authorities cited index of evolution modern synthesis shows indirectly whom huxley regarded important contributors synthesis 1941 (the book published in 1942, , references go 1941). authorities cited 20 or more times are:

darlington, darwin, dobzhansky, fisher, ford, goldschmidt, haldane, j. s. huxley, muller, rensch, turrill, wright.

this list contains few surprises. goldschmidt influential geneticist advocated evolution saltation, , mentioned in disagreement. turrill provided huxley botanical information. list omits 3 key members of synthesis listed above: mayr, stebbins botanist , simpson palaeontologist. mayr gets 16 citations , more in 2 later editions; 3 published outstanding , relevant books years later, , contribution synthesis unquestionable. lesser weight in huxley s citations caused publication date of book. huxley s book not strong in palaeontology, illustrates why simpson s later works such important contribution.
it huxley coined terms new synthesis , evolutionary synthesis; invented term cline in 1938 refer species members fall series of sub-species continuous change in characters on geographical area. classic example of cline circle of subspecies of gull larus round arctic zone. cline example of ring species.

some of huxley s last contributions evolutionary synthesis on subject of ecological genetics. noted how surprisingly widespread polymorphism in nature, visible morphism more prevalent in groups others. immense diversity of colour , pattern in small bivalve molluscs, brittlestars, sea-anemones, tubicular polychaetes , various grasshoppers perhaps maintained making recognition predators more difficult.

evolutionary progress


huxley believed on broad view evolution led advances in organisation. progress without goal 1 of phrases, distinguish point of view classical aristotelian teleology. ordinary man, or @ least ordinary poet, philosopher , theologian, anxious find purpose in evolutionary process. believe reasoning totally false.

the idea of evolutionary progress subjected fierce criticism in latter part of twentieth century. cladists, example, (and are) against suggestion group scientifically described advanced , others primitive. them, , radical group of transformed cladists, there no such thing advanced group, derived or apomorphic. primitive groups plesiomorphic. ironically, huxley invented terms clade , grades.

however, take rather extreme case, seem strange when man compared bacteria, mankind not vastly more complex , advanced form of life; or invasion of land plants , animals not great advance in history of life on planet. on issue julian @ opposite end of spectrum grandfather, was, @ least first half of career, propagandist persistent types , getting close denying advances @ all.
huxley argued case many times, in important works. in final chapter of evolution modern synthesis defines evolutionary progress raising of upper level of biological efficiency, being defined increased control on , independence of environment,

evolution in action discusses evolutionary progress @ length: natural selection plus time produces biological improvement… improvement not yet recognised technical term in biology … however, living things improved during evolution… darwin not afraid use word results of natural selection in general… believe improvement can become 1 of key concepts in evolutionary biology.

can scientifically defined? improvements in biological machinery… limbs , teeth of grazing horses… increase in brain-power… eyes of dragon-fly, can see round [it] in every direction, improvement on mere microscopic eye-spots of forms of life.

[over] whole range of evolutionary time see general advance—improvement in main properties of life, including general organization. advance useful term long-term improvement in general property of life. [but] improvement not universal. lower forms manage survive alongside higher .

these excerpts abbreviated, give idea of way of thinking. addresses topic of persistent types (living fossils) later in same book (pp 126–28).
the question of evolutionary advancement has quite history. of course, pre-darwin, believed without question man stood @ head of pyramid (scala naturae). matter not simple evolution natural selection; darwin s own opinion varied time time. in origin wrote , natural selection works , of each being, corporeal , mental endowments tend progress towards perfection . strong; sober remarks, there nothing in theory of natural selection demands selection must produce increase in complexity or other measure of advancement. merely compatible theory might happen. elsewhere darwin admits naturalists have not yet defined each other s satisfaction meant high , low forms (p. 336); nor have – 1 of problems. other evolutionary biologists have had similar thoughts huxley: g. ledyard stebbins , bernhard rensch, example. term progressive evolution anagenesis, though not include idea of improvement.

the objective description of complexity 1 of issues addressed cybernetics in 1950s. idea advanced machines (including living beings) exert more control on environments , operate in wider range of situations perhaps serves basis making terms such advanced amenable more exact definition. debate continues today.

for modern survey of idea of progress in evolution see nitecki , dawkins.