p240
計算機言語についての補足
生成文法批判
p195の補註で引用した D. L. Everett, Don’t Sleep, There Are Snakes Life and language in the Amazonian jungle (Pantheon 2008)の第二部には事実に即した生成文法批判が載っている．
ヒトの進化
Nature 445 915 (2007)
＊H. pylori seems to have spread from east Africa around 58,000 yr ago.
何回に分かれて出てきたかは確定していない．たとえば
PNAS 106 6094 (2009)
＊The early modern group has more shape variation than any other group in our sample, which covers 1.8 million years.
＊Rather than a single out-of-Africa dispersal scenario, we suggest that early modern humans were already divided into different populations in Pleistocene Africa, after which there followed a complex migration pattern.
しかし，これは形態学的論文なのでたいして当てにはならないだろう．
Human phylo according to haplotype hetrozygosity
少なくとも二回はあったというのは定説であろう．
そしてユーラシアの海岸沿いに極めて急速に分布は広がった．
巨大哺乳類(ゾウなど)の絶滅とヒトの分布域拡張を結び付ける説には賛否両論がある．
BrantinghamGlobal archaeological evidence for proboscidean overkill
PNAS 102 6231 (2005)
しかし，次のような説も出た:
Megafaunal extinctions, YD cooling, and termination of Clovis culture are due to an extraterrestrial impact
だが
Paleoindian demography does not support the extraterrestrial impact hypothesis
Buchanan et al., Paleoindian demography and the extraterrestrial impact hypothesis
PNAS 105 11651 (2008)
＊The results of the analyses were not consistent with the predictions of extraterrestrial impact hypothesis.
関連した興味深い話は
Leonard et al., Megafaunal Extinctions and the Disappearance of a Specialized Wolf Ecomorph
Curr Biol 17 1146 (2007)
Megafauna-adapted genetically distinct from the modern wolves
上の話は北アメリカだが，オーストラリアでも同じような話がある:
PNAS 102 6231 (2005)
Wroe et al., Prolonged coexistence of humans and megafauna in Pleistocene Australia
PNAS 102 8381 (2005)
Recent claims for continent wide disappearance of megafauna at 46.5 thousand calendar years ago (ka) to support a ‘‘blitzkrieg’’ model, must be reconsidered 36-30 ka unequivocal coexistence at Cuddie Springs
最近の大ニュースはH. floresiensisがH. erectusよりも昔にわれわれから分岐した可能性である:
H floresiensis from H sp more archaic than H erectus ?
Jungers et al. The foot of Homo floresiensis Nature 459 81 (2009)
＊In PBS program NOVA it was compared with Lucy.
中石器革命について
次の文献がたぶん適当な入門文献であろう．
現代的な意味の言語の発生がこの時代であろうと考えられている．芸術の起源
Bouzougga et al., 82,000-year-old shell bead s from North Africa and implications for the origins of modern human behavior
PNAS 104 9964 (2007)
Nassarius gibbosulus shell beads of 82,000 years ago confirmed.
計算機言語は単純な文法体系によって規定される．こうしなければならない理由は，ある陳述の正しさの判定を言語の世界の外に求めるわけには行かないから，正しさが判定できるために「言語」を簡単な規則の上に組み立てて行かざるを得ないからだ．こうして，文法の体系は有限的なものであり，再帰的な定義がほとんど可能な唯一の形式となる．
これに対して，自然言語が完全には再帰的ではなく，また有限の体系でもなさそうだということは多くの人々の感じていることだろう．今まで論じてきたことから明らかなように，その理由は自然言語がそれよりも さらに複雑な系を母胎にしているからである．しかし，チョムスキーの真摯な努力を誘うだけの形式化可能性を自然言語が示唆するということもまた重要な事実である(自然言語は「結晶化」してきたという比喩が使えるかもしれない)．記述文法が昔から考察の対象になったことも重要である．つまり，自然言語はかなり再帰的に形式化できる．どうしてそうなのか，ということは興 味深い問題である(ダーウィン過程で到達可能な複雑性に限界があるらしいこととこれは関係しているのかもしれない).
ついでながら，自然知能と人工知能にはまた別の深刻な違いがあるように思われる．それは硬件(ハードウェア)と軟件(ソフトウェア)の区別がどこまで厳然としているかである．人工知能はニューラルネットのようなものでもこの区別は截然としている．これに対してわれわれはたぶんそうなってはいない．したがって「胡蝶の夢」のような疑問を抱くことができる．つまり，話がソフトの中で閉じていないのである．軟件が硬件から独立していないということは複雑な系の重要な特徴であるかも知れない．
2009年9/23追加
最近号のPNAS 106 (38)に次の特集がある
Out of Africa: Modern Human Origins Special Feature
Perspective
*Ian Tattersall Human origins: Out of Africa 16018-16021 Perspective
*T imothy D. Weaver The meaning of Neandertal skeletal morphology 16028-16033 Research Articles
*J. J. Hublin The origin of Neandertals 16022-16027
Michael P. Richards and Erik Trinkaus Isotopic evidence for the diets of European Neanderthals and early modern humans 16034-16039
* John F. Hoffecker The spread of modern humans in Europe 16040-16045
* G. Philip Rightmire Middle and later Pleistocene hominins in Africa and Southwest Asia 16046-16050 * d'Errico, Marian Vanhaeren, Nick Barton, Abdeljalil Bouzouggar, Henk Mienis, Daniel Richter, Jean-Jacques Hublin, Shannon P. McPherron, and Pierre Lozouet Additional evidence on the use of personal ornaments in the Middle Paleolithic of North Africa 16051-16056 * Michael DeGiorgio, Mattias Jakobsson, and Noah A. Rosenberg Explaining worldwide patterns of human genetic variation using a coalescent-based serial founder model of migration outward from Africa 16057-16062
われわれの直系の先祖がアフリカから出てきたことには疑問の余地がない．次のような傍証もある:
Helicobacter pyrori is from Africa
Linz An African origin for the intimate association between humans and Helicobacter pylori
＊Anatomically modern humans were already infected by H. pylori before their migrations from Africa and demonstrate that H. pylori has remained intimately associated with their human host populations ever since.
Gunz et al., Early modern human diversity suggests subdivided population structure and a complex out-of-Africa scenario
＊Phenotype of neurocranial geometry to compare the variation in early modern human (200-160 kaBP) fossils with that in other groups of fossil Homo and recent modern humans.
Li et al., Worldwide Human Relationships Inferred from Genome-Wide Patterns of Variation
Science 319, 1100 (2008).
＊938 unrelated individuals from 51 populations of the Human Genome Diversity Panel at 650,000 common single-nucleotide polymorphism loci.
＊Individual ancestry and population substructure were detectable with very high resolution.
＊The relationship between haplotype heterozygosity and distance from Addis Ababa was consistent with the hypothesis of a serial founder effect with a single origin in sub-Saharan Africa.
MellarsWhy did modern human populations disperse from Africa ca. 60,000 years ago ? A new model
PNAS 103 9381 (2006)
110-90kBP: temporary dispersal to southeast Asia (eg Qafze) associated with clear symbolic expression (their cultural level was not sufficient to withstand competition from the long-established Neanderthal); 80-70kBP rapid climatic and environmental changes in Africa (the transition from oxygen isotope stage 5 to stage 4), major social and tech change (induced by mutation?); 70-60kBP Major population expansion in Africa from a small source area. 60kBP Out of Africa.
Macaulay et al., Single, Rapid Coastal Settlement of Asia Revealed by Analysis of Complete Mitochondrial Genomes Science 308 1034 (2005)
Only a single dispersal from Africa, most likely via a southern coastal route, through India and onward into southeast Asia and Australasia occurred 65,000 years ago, most likely taking only a few thousand years.
ユーラシア各地で多系的に各地で一斉にHomo erectusから進化したなどというとうてい正気とは思えない説の信奉者がまだいるらしいのは驚きではある．しかし，それはある意味では人間観の違いに由来している．人間とは度しがたく攻撃的な動物であるという立場をとるとき，一斉進化などは考えるだけアホらしい．
著者ははっきりとヒトは種の性向として攻撃的であると見る．これは何も直接的に対決して殺し合いたがると言っているのではないが，環境の使い方，他の動物への対処の仕方などすべてにおいて「攻撃的」である．狩猟採集民での成人男性の死因の最たるものは殺人であることも参考になろう．種としての性向がありうることはチンパンジーとボノボをくらべれば明らかである．彼らはわれわれとほとんど同属と言っていい生きものたちである．
Prehistoric human range expansion resulted in localized extinction events. In the present and the past, proboscideans have survived in refugia that are largely inaccessible to human populations.
Firestone et al., Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling
PNAS 104 16016 (2007)
(BG) A carbon-rich black layer, dating to ca 12.9 ka, has been previously identified at ca50 Clovis-age sites across North America, contemporaneous with the abrupt onset of Younger Dryas (YD) cooling. The in situ bones of extinct Pleistocene megafauna, along with Clovis tool assemblages, occur below this black layer but not within or above it.
＊An extraterrestrial (ET) impact event at ca 12.9 ka found: (i) magnetic grains with iridium, (ii) magnetic microspherules, (iii) charcoal, (iv) soot, (v) carbon spherules, (vi) glass-like carbon containing nanodiamonds, and (vii) fullerenes with ET helium.
Miller et al., Ecosystem Collapse in Pleistocene Australia and a Human Role in Megafaunal ExtinctionScience 309 287 (2005)
Brantingham et al., Global archaeological evidence for proboscidean overkill
Prehistoric human range expansion resulted in localized extinction events. In the present and the past, proboscideans have survived in refugia that are largely inaccessible to human populations.
＊LB1's foot is exceptionally long relative to the femur and tibia, proportions never before documented in hominins but seen in some African apes. Although the metatarsal robusticity sequence
＊It is possible that the ancestor of H. floresiensis was not Homo erectus but instead some other, more primitive, hominin whose dispersal into southeast Asia is still undocumented.
Bar-Yosef THE UPPER PALEOLITHIC REVOLUTION Ann Rev Anthropology 31 363 (2002)
＊These findings imply an early distribution of bead-making in Africa and southwest Asia at least 40 millennia before the appearance of similar cultural manifestations in Europe.
あるいは投げることの出来る武器 ( Science 308 491 (2005)に解説あり）などの技術革新がかなり同時に現れたと考えられている．
Origin of projectile launcher : lightweight points associated with projectile launchers originated in Africa (40-50 ky). Modern humans had a technological advantage when they left Africa and spread around the globe. ``These lightweight points show up more than 50,000 years ago in Africa,'' says Stan Ambrose (UIUC). ``They may have helped modern humans get out of Africa.''