darwin and modern science-第7节

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thmism；〃　the　idea　of　an　〃inherent　growth…force〃　and　at　the　same　time　he　held　that　〃the　way　of　life　powerfully　reacts　upon　all　form〃　and　that　the　orderly　growth　of　form　〃yields　to　change　from　externally　acting　causes。〃

Besides　Buffon；　Erasmus　Darwin；　Lamarck；　Treviranus；　and　Goethe；　there　were　other　〃pioneers　of　evolution；〃　whose　views　have　been　often　discussed　and　appraised。　　Etienne　Geoffroy　Saint…Hilaire　（1772…1844）；　whose　work　Goethe　so　much　admired；　was　on　the　whole　Buffonian；　emphasising　the　direct　action　of　the　changeful　milieu。　　〃Species　vary　with　their　environment；　and　existing　species　have　descended　by　modification　from　earlier　and　somewhat　simpler　species。〃　　He　had　a　glimpse　of　the　selection　idea；　and　believed　in　mutations　or　sudden　leapsinduced　in　the　embryonic　condition　by　external　influences。　　The　complete　history　of　evolution…theories　will　include　many　instances　of　guesses　at　truth　which　were　afterwards　substantiated；　thus　the　geographer　von　Buch　（1773…1853）　detected　the　importance　of　the　Isolation　factor　on　which　Wagner；　Romanes；　Gulick　and　others　have　laid　great　stress；　but　we　must　content　ourselves　with　recalling　one　other　pioneer；　the　author　of　the　〃Vestiges　of　Creation〃　（1844）；　a　work　which　passed　through　ten　editions　in　nine　years　and　certainly　helped　to　harrow　the　soil　for　Darwin's　sowing。　　As　Darwin　said；　〃it　did　excellent　service　in　this　country　in　calling　attention　to　the　subject；　in　removing　prejudice；　and　in　thus　preparing　the　ground　for　the　reception　of　analogous　views。〃　　（〃Origin　of　Species〃　（6th　edition）；　page　xvii。）　　Its　author；　Robert　Chambers　（1802…　1871）　was　in　part　a　Buffonianmaintaining　that　environment　moulded　organisms　adaptively；　and　in　part　a　Goethianbelieving　in　an　inherent　progressive　impulse　which　lifted　organisms　from　one　grade　of　organisation　to　another。

AS　REGARDS　NATURAL　SELECTION。

The　only　thinker　to　whom　Darwin　was　directly　indebted；　so　far　as　the　theory　of　Natural　Selection　is　concerned；　was　Malthus；　and　we　may　once　more　quote　the　well…known　passage　in　the　Autobiography：　　〃In　October；　1838；　that　is；　fifteen　months　after　I　had　begun　my　systematic　enquiry；　I　happened　to　read　for　amusement　'Malthus　on　Population'；　and　being　well　prepared　to　appreciate　the　struggle　for　existence　which　everywhere　goes　on　from　long…　continued　observation　of　the　habits　of　animals　and　plants；　it　at　once　struck　me　that　under　these　circumstances　favourable　variations　would　tend　to　be　preserved；　and　unfavourable　ones　to　be　destroyed。　　The　result　of　this　would　be　the　formation　of　new　species。〃　　（〃The　Life　and　Letters　of　Charles　Darwin〃；　Vol。　1。　page　83。　　London；　1887。）

Although　Malthus　gives　no　adumbration　of　the　idea　of　Natural　Selection　in　his　exposition　of　the　eliminative　processes　which　go　on　in　mankind；　the　suggestive　value　of　his　essay　is　undeniable；　as　is　strikingly　borne　out　by　the　fact　that　it　gave　to　Alfred　Russel　Wallace　also　〃the　long…sought　clue　to　the　effective　agent　in　the　evolution　of　organic　species。〃　　（A。R。　Wallace；　〃My　Life；　A　Record　of　Events　and　Opinions〃；　London；　1905；　Vol。　1。　page　232。）　　One　day　in　Ternate　when　he　was　resting　between　fits　of　fever；　something　brought　to　his　recollection　the　work　of　Malthus　which　he　had　read　twelve　years　before。　　〃I　thought　of　his　clear　exposition　of　'the　positive　checks　to　increase'disease；　accidents；　war；　and　faminewhich　keep　down　the　population　of　savage　races　to　so　much　lower　an　average　than　that　of　more　civilized　peoples。　　It　then　occurred　to　me　that　these　causes　or　their　equivalents　are　continually　acting　in　the　case　of　animals　also；　and　as　animals　usually　breed　much　more　rapidly　than　does　mankind；　the　destruction　every　year　from　these　causes　must　be　enormous　in　order　to　keep　down　the　numbers　of　each　species；　since　they　evidently　do　not　increase　regularly　from　year　to　year；　as　otherwise　the　world　would　long　ago　have　been　densely　crowded　with　those　that　breed　most　quickly。　　Vaguely　thinking　over　the　enormous　and　constant　destruction　which　this　implied；　it　occurred　to　me　to　ask　the　question；　Why　do　some　die　and　some　live？　　And　the　answer　was　clearly；　that　on　the　whole　the　best　fitted　live。　　From　the　effects　of　disease　the　most　healthy　escaped；　from　enemies　the　strongest；　the　swiftest；　or　the　most　cunning；　from　famine　the　best　hunters　or　those　with　the　best　digestion；　and　so　on。　　Then　it　suddenly　flashed　upon　me　that　this　self…　acting　process　would　necessarily　IMPROVE　THE　RACE；　because　in　every　generation　the　inferior　would　inevitably　be　killed　off　and　the　superior　would　remainthat　is；　THE　FITTEST　WOULD　SURVIVE。〃　　（Ibid。　Vol。　1。　page　361。）　　We　need　not　apologise　for　this　long　quotation；　it　is　a　tribute　to　Darwin's　magnanimous　colleague；　the　Nestor　of　the　evolutionist　camp；and　it　probably　indicates　the　line　of　thought　which　Darwin　himself　followed。　　It　is　interesting　also　to　recall　the　fact　that　in　1852；　when　Herbert　Spencer　wrote　his　famous　〃Leader〃　article　on　〃The　Development　Hypothesis〃　in　which　he　argued　powerfully　for　the　thesis　that　the　whole　animate　world　is　the　result　of　an　age…long　process　of　natural　transformation；　he　wrote　for　〃The　Westminster　Review〃　another　important　essay；　〃A　Theory　of　Population　deduced　from　the　General　Law　of　Animal　Fertility〃；　towards　the　close　of　which　he　came　within　an　ace　of　recognising　that　the　struggle　for　existence　was　a　factor　in　organic　evolution。　　At　a　time　when　pressure　of　population　was　practically　interesting　men's　minds；　Darwin；　Wallace；　and　Spencer　were　being　independently　led　from　a　social　problem　to　a　biological　theory。　　There　could　be　no　better　illustration；　as　Prof。　Patrick　Geddes　has　pointed　out；　of　the　Comtian　thesis　that　science　is　a　〃social　phenomenon。〃

Therefore；　as　far　more　important　than　any　further　ferreting　out　of　vague　hints　of　Natural　Selection　in　books　which　Darwin　never　read；　we　would　indicate　by　a　quotation　the　view　that　the　central　idea　in　Darwinism　is　correlated　with　contemporary　social　evolution。　　〃The　substitution　of　Darwin　for　Paley　as　the　chief　interpreter　of　the　order　of　nature　is　currently　regarded　as　the　displacement　of　an　anthropomorphic　view　by　a　purely　scientific　one：　　a　little　reflection；　however；　will　show　that　what　has　actually　happened　has　been　merely　the　replacement　of　the　anthropomorphism　of　the　eighteenth　century　by　that　of　the　nineteenth。　　For　the　place　vacated　by　Paley's　theological　and　metaphysical　explanation　has　simply　been　occupied　by　that　suggested　to　Darwin　and　Wallace　by　Malthus　in　terms　of　the　prevalent　severity　of　industrial　competition；　and　those　phenomena　of　the　struggle　for　existence　which　the　light　of　contemporary　economic　theory　has　enabled　us　to　discern；　have　thus　come　to　be　temporarily　exalted　into　a　complete　explanation　of　organic　progress。〃　　（P。　Geddes；　article　〃Biology〃；　〃Chambers's　Encyclopaedia〃。）　　It　goes　without　saying　that　the　idea　suggested　by　Malthus　was　developed　by　Darwin　into　a　biological　theory　which　was　then　painstakingly　verified　by　being　used　as　an　interpretative　formula；　and　that　the　validity　of　a　theory　so　established　is　not　affected　by　what　suggested　it；　but　the　practical　question　which　this　line　of　thought　raises　in　the　mind　is　this：　　if　Biology　did　thus　borrow　with　such　splendid　results　from　social　theory；　why　should　we　not　more　deliberately　repeat　the　experiment？

Darwin　was　characteristically　frank　and　generous　in　admitting　that　the　principle　of　Natural　Selection　had　been　independently　recognised　by　Dr　W。C。　Wells　in　1813　and　by　Mr　Patrick　Matthew　in　1831；　but　he　had　no　knowledge　of　these　anticipations　when　he　published　the　first　edition　of　〃The　Origin　of　Species〃。　　Wells；　whose　〃Essay　on　Dew〃　is　still　remembered；　read　in　1813　before　the　Royal　Society　a　short　paper　entitled　〃An　account　of　a　White　Female；　part　of　whose　skin　resembles　that　of　a　Negro〃　（published　in　1818）。　　In　this　communication；　as　Darwin　said；　〃he　observes；　firstly；　that　all　animals　tend　to　vary　in　some　degree；　and；　secondly；　that　agriculturists　improve　their　domesticated　animals　by　selection；　and　then；　he　adds；　but　what　is　done　in　this　latter　case　'by　art；　seems　to　be　done　with　equal　efficacy；　though　more　slowly；　by　nature；　in　the　formation　of　varieties　of　mankind；　fitted　for　the　country　which　they　inhabit。'〃　　（〃Origin　of　Species〃　（6th　edition）　page　xv。）　　Thus　Wells　had　the　clear　idea　of　survival　dependent　upon　a　favourable　variation；　but　he　makes　no　more　use　of　the　idea　and　applies　it　only　to　man。　　There　is　not　in　the　paper　the　least　hint　that　the　author　ever　thought　of　generalising　the　remarkable　sentence　quoted　above。

Of　Mr　Patrick　Matthew；　who　buried　his　treasure　in　an　appendix　to　a　work　on　〃Naval　Timber　and　Arboriculture〃；　Darwin　said　that　〃he　clearly　saw　the　full　force　of　the　principle　of　natural　selection。〃　　In　1860　Darwin　wrotevery　characteristicallyabout　this　to　Lyell：　　〃Mr　Patrick　Matthew　publishes　a　long　extract　from　his　work　on　〃Naval　Timber　and　Arboriculture〃；　published　in　1831；　in　which　he　briefly　but　completely　anticipates　the　theory　of　Natural　Selection。　　I　have　ordered　the　book；　as　some　passages　are　rather　obscure；　but　it　is　certainly；　I　think；　a　complete　but　not　developed　anticipation。　　Erasmus　always　said　that　surely　this　would　be　shown　to　be　the　case　some　day。　　Anyhow；　one　may　be　excused　in　not　having　discovered　the　fact　in　a　work　on