on the relations of man to the lower animals-第5部分

快捷操作: 按键盘上方向键 ← 或 → 可快速上下翻页 按键盘上的 Enter 键可回到本书目录页 按键盘上方向键 ↑ 可回到本页顶部! 如果本书没有阅读完，想下次继续接着阅读，可使用上方 "收藏到我的浏览器" 功能 和 "加入书签" 功能！


cavity　of　different　races　of　mankind　is　far　greater；　absolutely；　than
that　between　the　lowest　Man　and　the　highest　Ape；　while；　relatively；　it
is　about　the　same。　　For　the　largest　human　skull　measured　by　Morton
contained　114　cubic　inches；　that　is　to　say；　had　very　nearly　double　the
capacity　of　the　smallest；　while　its　absolute　preponderance；　of　52　cubic
inchesis　far　greater　than　that　by　which　the　lowest　adult　male　human
cranium　surpasses　the　largest　of　the　Gorillas　（62　…　34…1/2　=　27…1/2）。
Secondly；　the　adult　crania　of　Gorillas　which　have　as　yet　been　measured
differ　among　themselves　by　nearly　one…third；　the　maximum　capacity　being
34。5　cubic　inches；　the　minimum　24　cubic　inches；　and；　thirdly；　after
making　all　due　allowance　for　difference　of　size；　the　cranial　capacities
of　some　of　the　lower　Apes　fall　nearly　as　much；　relatively；　below　those
of　the　higher　Apes　as　the　latter　fall　below　Man。

Thus；　even　in　the　important　matter　of　cranial　capacity；　Men　differ　more
widely　from　one　another　than　they　do　from　the　Apes；　while　the　lowest
Apes　differ　as　much；　in　proportion；　from　the　highest；　as　the　latter
does　from　Man。　　The　last　proposition　is　still　better　illustrated　by　the
study　of　the　modifications　which　other　parts　of　the　cranium　undergo　in
the　Simian　series。

It　is　the　large　proportional　size　of　the　facial　bones　and　the　great
projection　of　the　jaws　which　confers　upon　the　Gorilla's　skull　its　small
facial　angle　and　brutal　character。

FIG。　16。Sections　of　the　skulls　of　Man　and　various　Apes；　drawn　so　as　to
give　the　cerebral　cavity　the　same　length　in　each　case；　thereby
displaying　the　varying　proportions　of　the　facial　bones。　　The　line　'b'
indicates　the　plane　of　the　tentorium；　which　separates　the　cerebrum　from
the　cerebellum；　'd'；　the　axis　of　the　occipital　outlet　of　the　skull。　The
extent　of　cerebral　cavity　behind　'c'；　which　is　a　perpendicular　erected
on　'b'　at　the　point　where　the　tentorium　is　attached　posteriorly；
indicates　the　degree　to　which　the　cerebrum　overlaps　the　cerebellumthe
space　occupied　by　which　is　roughly　indicated　by　the　dark　shading。　　In
comparing　these　diagrams；　it　must　be　recollected；　that　figures　on　so
small　a　scale　as　these　simply　exemplify　the　statements　in　the　text；　the
proof　of　which　is　to　be　found　in　the　objects　themselves。

But　if　we　consider　the　proportional　size　of　the　facial　bones　to　the
skull　proper　only；　the　little　'Chrysothrix'　（Fig。　16）　differs　very
widely　from　the　Gorilla；　and；　in　the　same　way；　as　Man　does；　while　the
Baboons　（'Cynocephalus'；　Fig。　16）　exaggerate　the　gross　proportions　of
the　muzzle　of　the　great　Anthropoid；　so　that　its　visage　looks　mild　and
human　by　comparison　with　theirs。　　The　difference　between　the　Gorilla
and　the　Baboon　is　even　greater　than　it　appears　at　first　sight；　for　the
great　facial　mass　of　the　former　is　largely　due　to　a　downward　development
of　the　jaws；　an　essentially　human　character；　superadded　upon　that
almost　purely　forward；　essentially　brutal；　development　of　the　same
parts　which　characterizes　the　Baboon；　and　yet　more　remarkably
distinguishes　the　Lemur。

Similarly；　the　occipital　foramen　of　'Mycetes'　（Fig。　16）；　and　still　more
of　the　Lemurs；　is　situated　completely　in　the　posterior　face　of　the
skull；　or　as　much　further　back　than　that　of　the　Gorilla；　as　that　of　the
Gorilla　is　further　back　than　that　of　Man；　while；　as　if　to　render　patent
the　futility　of　the　attempt　to　base　any　broad　classificatory
distinction　on　such　a　character；　the　same　group　of　Platyrhine；　or
American　monkeys；　to　which　the　Mycetes　belongs；　contains　the
Chrysothrix；　whose　occipital　foramen　is　situated　far　more　forward　than
in　any　other　ape；　and　nearly　approaches　the　position　it　holds　in　Man。

Again；　the　Orang's　skull　is　as　devoid　of　excessively　developed
supraciliary　prominences　as　a　Man's；　though　some　varieties　exhibit
great　crests　elsewhere　（See　pp。　231；　232）；　and　in　some　of　the　Cebine
apes　and　in　the　'Chrysothrix'；　the　cranium　is　as　smooth　and　rounded　as
that　of　Man　himself。

What　is　true　of　these　leading　characteristics　of　the　skull；　holds　good；
as　may　be　imagined；　of　all　minor　features；　so　that　for　every　constant
difference　between　the　Gorilla's　skull　and　the　Man's；　a　similar
constant　difference　of　the　same　order　（that　is　to　say；　consisting　in
excess　or　defect　of　the　same　quality）　may　be　found　between　the
Gorilla's　skull　and　that　of　some　other　ape。　　So　that；　for　the　skull；　no
less　than　for　the　skeleton　in　general；　the　proposition　holds　good；　that
the　differences　between　Man　and　the　Gorilla　are　of　smaller　value　than
those　between　the　Gorilla　and　some　other　Apes。

In　connection　with　the　skull；　I　may　speak　of　the　teethorgans　which
have　a　peculiar　classificatory　value；　and　whose　resemblances　and
differences　of　number；　form；　and　succession；　taken　as　a　whole；　are
usually　regarded　as　more　trustworthy　indicators　of　affinity　than　any
others。

FIG。　17。Lateral　views；　of　the　same　length；　of　the　upper　jaws　of
various　Primates。　　'i'；　incisors；　'c'；　canines'　'pm'；　premolars；　'm'；
molars。　　A　line　is　drawn　through　the　first　molar　of　Man；　'Gorilla'；
'Cynocephalus'；　and　'Cebus'；　and　the　grinding　surface　of　the　second
molar　is　shown　in　each；　its　anterior　and　internal　angle　being　just
above　the　'm'　of　'm2'。

Man　is　provided　with　two　sets　of　teethmilk　teeth　and　permanent　teeth。
The　former　consist　of　four　incisors；　or　cutting　teeth；　two　canines；　or
eyeteeth；　and　four　molars；　or　grinders；　in　each　jawmaking　twenty　in
all。　　The　latter　（Fig。　17）　comprise　four　incisors；　two　canines；　four
small　grinders；　called　premolars　or　false　molars；　and　six　large
grinders；　or　true　molars；　in　each　jawmaking　thirty…two　in　all。　　The
internal　incisors　are　larger　than　the　external　pair；　in　the　upper　jaw；
smaller　than　the　external　pair；　in　the　lower　jaw。　　The　crowns　of　the
upper　molars　exhibit　four　cusps；　or　blunt…pointed　elevations；　and　a
ridge　crosses　the　crown　obliquely；　from　the　inner；　anterior　cusp　to　the
outer；　posterior　cusp　（Fig。　17　m2）。　　The　anterior　lower　molars　have
five　cusps；　three　external　and　two　internal。　　The　premolars　have　two
cusps；　one　internal　and　one　external；　of　which　the　outer　is　the　higher。

In　all　these　respects　the　dentition　of　the　Gorilla　may　be　described　in
the　same　terms　as　that　of　Man；　but　in　other　matters　it　exhibits　many
and　important　differences　（Fig。　17）。

Thus　the　teeth　of　man　constitute　a　regular　and　even　serieswithout　any
break　and　without　any　marked　projection　of　one　tooth　above　the　level　of
the　rest；　a　peculiarity　which；　as　Cuvier　long　ago　showed；　is　shared　by
no　other　mammal　save　oneas　different　a　creature　from　man　as　can　well
be　imaginednamely；　the　long　extinct　'Anoplotherium'。　　The　teeth　of　the
Gorilla；　on　the　contrary；　exhibit　a　break；　or　interval；　termed　the
'diastema'；　in　both　jaws：　in　front　of　the　eye…tooth；　or　between　it　and
the　outer　incisor；　in　the　upper　jaw；　behind　the　eyetooth；　or　between　it
and　the　front　false　molar；　in　the　lower　jaw。　　Into　this　break　in　the
series；　in　each　jaw；　fits　the　canine　of　the　opposite　jaw；　the　size　of
the　eye…tooth　in　the　Gorilla　being　so　great　that　it　projects；　like　a
tusk；　far　beyond　the　general　level　of　the　other　teeth。　　The　roots　of
the　false　molar　teeth　of　the　Gorilla；　again；　are　more　complex　than　in
Man；　and　the　proportional　size　of　the　molars　is　different。　　The　Gorilla
has　the　crown　of　the　hindmost　grinder　of　the　lower　jaw　more　complex；
and　the　order　of　eruption　of　the　permanent　teeth　is　different；　the
permanent　canines　making　their　appearance　before　the　second　and　third
molars　in　Man；　and　after　them　in　the　Gorilla。

Thus；　while　the　teeth　of　the　Gorilla　closely　resemble　those　of　Man　in
number；　kind；　and　in　the　general　pattern　of　their　crowns；　they　exhibit
marked　differences　from　those　of　Man　in　secondary　respects；　such　as
relative　size；　number　of　fangs；　and　order　of　appearance。

But；　if　the　teeth　of　the　Gorilla　be　compared　with　those　of　an　Ape；　no
further　removed　from　it　than　a　'Cynocephalus'；　or　Baboon；　it　will　be
found　that　differences　and　resemblances　of　the　same　order　are　easily
observable；　but　that　many　of　the　points　in　which　the　Gorilla　resembles
Man　are　those　in　which　it　differs　from　the　Baboon；　while　various
respects　in　which　it　differs　from　Man　are　exaggerated　in　the
'Cynocephalus'。　　The　number　and　the　nature　of　the　teeth　remain　the　same
in　the　Baboon　as　in　the　Gorilla　and　in　Man。　　But　the　pattern　of　the
Baboon's　upper　molars　is　quite　different　from　that　described　above
（Fig。　17）；　the　canines　are　proportionally　longer　and　more　knife…like；
the　anterior　premolar　in　the　lower　jaw　is　specially　modified；　the
posterior　molar　of　the　lower　jaw　is　still　larger　and　more　complex　than
in　the　Gorilla。

Passing　from　the　old…world　Apes　to　those　of　the　new　world；　we　meet　with
a　change　of　much　greater　importance　than　any　of　these。　　In　such　a　genus
as　'Cebus'；　for　example　（Fig。　17）；　it　will　be　found　that　while　in　some
secondary　points；　such　as　the　projection　of　the　canines　and　the
diastema；　the　resemblance　to　the　great　ape　is　preserved；　in　other　and
most　important　respects；　the　dentition　is　extremely　different。　　Instead
of　20　teeth　in　the　milk　set；　there　are　24：　instead　of　32　teeth　in　the
permanent　set；　there　are　36；　the　false　molars　being　increased　from　eight
to　twelve。　　And　in　form；　the　crowns　of　the　molars　are　very　unlike　those
of　the　Gorilla；　and　differ　far　more　widely　from　the　human　pattern。

The　Marmosets；　on　the　other　hand；　exhibit　the　same　number　of　teeth　as
Man　and　the　Gorilla；　but；　notwithstanding　this；　their　dentition　is　very
different；　for　they　have　four　more　false　molars；　like　the　other
American　monkeysbut　as　they　have　four　fewer　true　molars；　the　total
remains　the　same。　　And　passing　from　the　American　apes　to　the　Lemurs；
the　dentition　becomes　still　more　completely　and　essentially　different
from　that　of　the　Gorilla。　　The　incisors　begin　to　vary　both　in　number
and　in　form。　　The　molars　acquire；　more　and　more；　a　many…pointed；
insectivorous　character；　and　in　one　Genus；　the　Aye…Aye　（'Cheiromys'）；
the　canines　disappear；　and　the　teeth　completely　simulate　those　of　a
Rodent　（Fig。　17）。

Hence　it　is　obvious　that；　greatly　as　the　dentition　of　the　highest　Ape
differs　from　that　of　Man；　it　differs　far　more　widely　from　that　of　the
lower　and　lowest　Ape