darwin and modern science-第41节

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onvinced　of　the　influence　of　external　conditions。　　In　1876；　that　is；　two　years　after　the　appearance　of　the　second　edition　of　〃The　Descent　of　Man〃；　he　writes　with　his　usual　candid　honesty：　　〃In　my　opinion　the　greatest　error　which　I　have　committed；　has　been　not　allowing　sufficient　weight　to　the　direct　action　of　the　environment；　i。e。　food；　climate；　etc。　independently　of　natural　selection。〃　　（Ibid。　Vol。　III。　page　159。）　　It　is　certain　from　this　change　of　opinion　that；　if　he　had　been　able　to　make　up　his　mind　to　issue　a　third　edition　of　〃The　Descent　of　Man〃；　he　would　have　ascribed　a　much　greater　influence　to　the　effect　of　external　conditions　in　explaining　the　different　characters　of　the　races　of　man　than　he　did　in　the　second　edition。　He　would　also　undoubtedly　have　attributed　less　influence　to　sexual　selection　as　a　factor　in　the　origin　of　the　different　bodily　characteristics；　if　indeed　he　would　not　have　excluded　it　altogether。

In　Part　III　of　the　〃Descent〃　two　additional　chapters　are　devoted　to　the　discussion　of　sexual　selection　in　relation　to　man。　　These　may　be　very　briefly　referred　to。　　Darwin　here　seeks　to　show　that　sexual　selection　has　been　operative　on　man　and　his　primitive　progenitor。　　Space　fails　me　to　follow　out　his　interesting　arguments。　　I　can　only　mention　that　he　is　inclined　to　trace　back　hairlessness；　the　development　of　the　beard　in　man；　and　the　characteristic　colour　of　the　different　human　races　to　sexual　selection。　　Since　bareness　of　the　skin　could　be　no　advantage；　but　rather　a　disadvantage；　this　character　cannot　have　been　brought　about　by　natural　selection。　　Darwin　also　rejected　a　direct　influence　of　climate　as　a　cause　of　the　origin　of　the　skin…colour。　　I　have　already　expressed　the　opinion；　based　on　the　development　of　his　views　as　shown　in　his　letters；　that　in　a　third　edition　Darwin　would　probably　have　laid　more　stress　on　the　influence　of　external　environment。　　He　himself　feels　that　there　are　gaps　in　his　proofs　here；　and　says　in　self…criticism：　　〃The　views　here　advanced；　on　the　part　which　sexual　selection　has　played　in　the　history　of　man；　want　scientific　precision。〃　　（〃Descent　of　Man〃；　page　924。）　　I　need　here　only　point　out　that　it　is　impossible　to　explain　the　graduated　stages　of　skin…　colour　by　sexual　selection；　since　it　would　have　produced　races　sharply　defined　by　their　colour　and　not　united　to　other　races　by　transition　stages；　and　this；　it　is　well　known；　is　not　the　case。　　Moreover；　the　fact　established　by　me　（〃Die　Hautfarbe　des　Menschen〃；　〃Mitteilungen　der　Anthropologischen　Gesellschaft　in　Wien〃；　Vol。　XXXIV。　pages　331…352。）；　that　in　all　races　the　ventral　side　of　the　trunk　is　paler　than　the　dorsal　side；　and　the　inner　surface　of　the　extremities　paler　than　the　outer　side；　cannot　be　explained　by　sexual　selection　in　the　Darwinian　sense。

With　this　I　conclude　my　brief　survey　of　the　rich　contents　of　Darwin's　book。　I　may　be　permitted　to　conclude　by　quoting　the　magnificent　final　words　of　〃The　Descent　of　Man〃：　　〃We　must；　however；　acknowledge；　as　it　seems　to　me；　that　man；　with　all　his　noble　qualities；　with　sympathy　which　feels　for　the　most　debased；　with　benevolence　which　extends　not　only　to　other　men　but　to　the　humblest　living　creature；　with　his　god…like　intellect　which　has　penetrated　into　the　movements　and　constitution　of　the　solar　systemwith　all　these　exalted　powersMan　still　bears　in　his　bodily　frame　the　indelible　stamp　of　his　lowly　origin。〃　　（Ibid。　page　947。）

What　has　been　the　fate　of　Darwin's　doctrines　since　his　great　achievement？　　How　have　they　been　received　and　followed　up　by　the　scientific　and　lay　world？　　And　what　do　the　successors　of　the　mighty　hero　and　genius　think　now　in　regard　to　the　origin　of　the　human　race？

At　the　present　time　we　are　incomparably　more　favourably　placed　than　Darwin　was　for　answering　this　question　of　all　questions。　　We　have　at　our　command　an　incomparably　greater　wealth　of　material　than　he　had　at　his　disposal。　　And　we　are　more　fortunate　than　he　in　this　respect；　that　we　now　know　transition…forms　which　help　to　fill　up　the　gap；　still　great；　between　the　lowest　human　races　and　the　highest　apes。　　Let　us　consider　for　a　little　the　more　essential　additions　to　our　knowledge　since　the　publication　of　〃The　Descent　of　Man〃。

Since　that　time　our　knowledge　of　animal　embryos　has　increased　enormously。　While　Darwin　was　obliged　to　content　himself　with　comparing　a　human　embryo　with　that　of　a　dog；　there　are　now　available　the　youngest　embryos　of　monkeys　of　all　possible　groups　（Orang；　Gibbon；　Semnopithecus；　Macacus）；　thanks　to　Selenka's　most　successful　tour　in　the　East　Indies　in　search　of　such　material。　　We　can　now　compare　corresponding　stages　of　the　lower　monkeys　and　of　the　Anthropoid　apes　with　human　embryos；　and　convince　ourselves　of　their　great　resemblance　to　one　another；　thus　strengthening　enormously　the　armour　prepared　by　Darwin　in　defence　of　his　view　on　man's　nearest　relatives。　　It　may　be　said　that　Selenka's　material　fils　up　the　blanks　in　Darwin's　array　of　proofs　in　the　most　satisfactory　manner。

The　deepening　of　our　knowledge　of　comparative　anatomy　also　gives　us　much　surer　foundations　than　those　on　which　Darwin　was　obliged　to　build。　　Just　of　late　there　have　been　many　workers　in　the　domain　of　the　anatomy　of　apes　and　lemurs；　and　their　investigations　extend　to　the　most　different　organs。　　Our　knowledge　of　fossil　apes　and　lemurs　has　also　become　much　wider　and　more　exact　since　Darwin's　time：　　the　fossil　lemurs　have　been　especially　worked　up　by　Cope；　Forsyth　Major；　Ameghino；　and　others。　　Darwin　knew　very　little　about　fossil　monkeys。　　He　mentions　two　or　three　anthropoid　apes　as　occurring　in　the　Miocene　of　Europe　（〃Descent　of　Man〃；　page　240。）；　but　only　names　Dryopithecus；　the　largest　form　from　the　Miocene　of　France。　　It　was　erroneously　supposed　that　this　form　was　related　to　Hylobates。　　We　now　know　not　only　a　form　that　actually　stands　near　to　the　gibbon　（Pliopithecus）；　and　remains　of　other　anthropoids　（Pliohylobates　and　the　fossil　chimpanzee；　Palaeopithecus）；　but　also　several　lower　catarrhine　monkeys；　of　which　Mesopithecus；　a　form　nearly　related　to　the　modern　Sacred　Monkeys　（a　species　of　Semnopithecus）　and　found　in　strata　of　the　Miocene　period　in　Greece；　is　the　most　important。　　Quite　recently；　too；　Ameghino's　investigations　have　made　us　acquainted　with　fossil　monkeys　from　South　America　（Anthropops；　Homunculus）；　which；　according　to　their　discoverer；　are　to　be　regarded　as　in　the　line　of　human　descent。

What　Darwin　missed　most　of　allintermediate　forms　between　apes　and　man　has　been　recently　furnished。　　（E。　Dubois；　as　is　well　known；　discovered　in　1893；　near　Trinil　in　Java；　in　the　alluvial　deposits　of　the　river　Bengawan；　an　important　form　represented　by　a　skull…cap；　some　molars；　and　a　femur。　　His　opinionmuch　disputed　as　it　has　beenthat　in　this　form；　which　he　named　Pithecanthropus；　he　has　found　a　long…desired　transition…form　is　shared　by　the　present　writer。　　And　although　the　geological　age　of　these　fossils；　which；　according　to　Dubois；　belong　to　the　uppermost　Tertiary　series；　the　Pliocene；　has　recently　been　fixed　at　a　later　date　（the　older　Diluvium）；　the　MORPHOLOGICAL　VALUE　of　these　interesting　remains；　that　is；　the　intermediate　position　of　Pithecanthropus；　still　holds　good。　　Volz　says　with　justice　（〃Das　geologische　Alter　der　Pithecanthropus…Schichten　bei　Trinil；　Ost…Java〃。　〃Neues　Jahrb。　f。Mineralogie〃。　　Festband；　1907。）；　that　even　if　Pithecanthropus　is　not　THE　missing　link；　it　is　undoubtedly　_A_　missing　link。

As　on　the　one　hand　there　has　been　found　in　Pithecanthropus　a　form　which；　though　intermediate　between　apes　and　man；　is　nevertheless　more　closely　allied　to　the　apes；　so　on　the　other　hand；　much　progress　has　been　made　since　Darwin's　day　in　the　discovery　and　description　of　the　older　human　remains。　　Since　the　famous　roof　of　a　skull　and　the　bones　of　the　extremities　belonging　to　it　were　found　in　1856　in　the　Neandertal　near　Dusseldorf；　the　most　varied　judgments　have　been　expressed　in　regard　to　the　significance　of　the　remains　and　of　the　skull　in　particular。　　In　Darwin's　〃Descent　of　Man〃　there　is　only　a　passing　allusion　to　them　（〃Descent　of　Man〃；　page　82。）　in　connection　with　the　discussion　of　the　skull…capacity；　although　the　investigations　of　Schaaffhausen；　King；　and　Huxley　were　then　known。　　I　believe　I　have　shown；　in　a　series　of　papers；　that　the　skull　in　question　belongs　to　a　form　different　from　any　of　the　races　of　man　now　living；　and；　with　King　and　Cope；　I　regard　it　as　at　least　a　different　species　from　living　man；　and　have　therefore　designated　it　Homo　primigenius。　　The　form　unquestionably　belongs　to　the　older　Diluvium；　and　in　the　later　Diluvium　human　forms　already　appear；　which　agree　in　all　essential　points　with　existing　human　races。

As　far　back　as　1886　the　value　of　the　Neandertal　skull　was　greatly　enhanced　by　Fraipont's　discovery　of　two　skulls　and　skeletons　from　Spy　in　Belgium。　　These　are　excellently　described　by　their　discoverer　（〃La　race　humaine　de　Neanderthal　ou　de　Canstatt　en　Belgique〃。　　〃Arch。　de　Biologie〃；　VII。　1887。）；　and　are　regarded　as　belonging　to　the　same　group　of　forms　as　the　Neandertal　remains。　　In　1899　and　the　following　years　came　the　discovery　by　Gorjanovic…　Kramberger　of　different　skeletal　parts　of　at　least　ten　individuals　in　a　cave　near　Krapina　in　Croatia。　　（Gorjanovic…Kramberger　〃Der　diluviale　Mensch　von　Krapin