p233

的を外しているということについて:

記号列が複雑か否かということは記号列そのものの性質で決まることではないので統語論的な研究をいくらしても記号列が複雑か否かに答えることは出来はしない．たがって，エントロピーだとか相互情報量などというような量だけで「複雑系」を特徴づけようとする試みはまったく的外れである．しかし，Complexity を役にたつあるいは意味のある数列のサプライザルで定義するというのがShostak の提案があるが，たとえば111111· · · が意味を持つときにはこの数列を複雑ということになり，やはりしっくりこない．

＊ついでながら，生きているものを生きていると判定できるかどうかの方がチューリングテストよりも良い知能検査であるかもしれない．このことは自然知能が何のために発達したかということに興味深い示唆を与えるように思われる．

＊この節からの３節はだいたい「生物学としての「複雑系研究」」，生物科学50, 97 (1998) および，“Complex systems study as biology,” Int. J. Mod. Phys. B, 12, 245 (1998) などの前半部分にもとづく．

命と炎

最近日本では生物の本質を物質代謝に求めるというような大時代の本がベストセラーになっている．もちろん，系を非平衡に保つために，そして構造的基本条件と第５章でよぶ複雑系の要件をこのノイズに満ちた世界で維持していくために，開放系として命がものを外とやりとりすることは必須である．しかし，そんなことは命と炎のアナロジーとして意識的無意識的に極めて昔からわれわれが体感していることである．

 火を使い始めたときから(つまり， Homo erectus の段階で，５０万年以上前)すでにこのような洞察はあ ったのではないだろうか．[妄想としては; われわれの属は「火の使用」で確立されたのではなかったか，つまりHomoのsynapomorphyは「火の使用」であり，Homo habililsはHomoに入れないほうがいいのではないか．道具の製作や使用ならチンパンジーにもある事に注意．

最近のScience  325 , 394 (2009)に火が人間を作ったと主張する次の2冊の本の書評 [A. Keller, The Cooking Ape] が現れた:

Richard Wrangham,  Catching Fire How Cooking Made Us Human

 Basic Books, New York, 2009. 315 pp. $26.95. ISBN 9780465013623.

Frances D. Burton,  Fire The Spark That Ignited Human Evolution

]

上に書いたことが妄想でないらしいことが最近の火についての総説に書いてある．

Importance of fire in paleontology and neontology

9 Pausas A Burning Story: The Role of Fire in the History of Life

BSc 59 593

*Wildfire appeared concomitant with the origin of terrestrial plants and played an important role throughout the history of life.

The prehuman era :

*The origin of fire is tied to the origin of plants. Before the appearance of photosynthetic

organisms, the atmosphere lacked sufficient oxygen, and before the appearance of terrestrial plants, it lacked fuels; thus, fire did not exist on our planet. With the earliest Silurian origins of land plants, there is evidence of fire. Glasspool and colleagues (2004) reported charred remains of low-growing vegetation of the earliest stomata-bearing plants (440 mya), plus charred coprolites, indicating a low-temperature surface fire.

*The subsequent fire history seems to be tied to atmospheric oxygen levels (Scott and Glasspool 2006). There is clear evidence of charcoal in the Devonian deposits (400 mya; Scott 2000, Glasspool et al. 2006), although extensive charcoal deposits do not appear until the late Paleozoic Era (345 mya; Falcon-Lang 2000, Scott 2000), concomitant with a rapid rise in atmospheric oxygen from the late Devonian to the late Carboniferous (figure 3). The

peak of approximately 31\% atmospheric oxygen during the Carboniferous (Berner 2006), compared with the current 21\%, would have greatly facilitated combustion. 

*The major fall in atmospheric oxygen levels during the Permian and the Triassic may explain the scant evidence for fires, as inferred from the few charcoal deposits found for this period. Nevertheless, during the remainder of the Mesozoic (Jurassic and Cretaceous periods), fires were increasingly important (Scott 2000). 

*Evidence that fire has actually altered the biogeography of landscapes and had major

impacts on ecosystem function may be tied to the late Tertiary. The dramatic rise in charcoal deposition in marine sediments (Herring 1985, Jia et al. 2003) is often cited as evidence

of the first rise in fire as an important ecosystem process. It has been postulated that the spread of C4 grasses during the more seasonal climate of the late Tertiary was due to this

increase in fire activity, which opened up woodlands and created environments favorable to C4 grasslands (Keeley and Rundel 2005). Although other factors, such as increasing aridity, have been invoked to explain this expansion of C4 grasslands, only fire can account for the fact that expansion was possible because these grasses shifted their distribution to more mesic environments. The high flammability of C4 grasses would have produced a feedback process that further increased fire activity, thus maintaining the grassland dominated

landscape, a process similar to the one currently maintaining many of our savannas. 

*Fire has most likely played a selective role in the evolution of sprouting in Northern Hemisphere gymnosperms; most lack any capacity for resprouting, as would be predicted

judging from their occurrence in forests typically subjected to low-intensity surface fires, which most mature trees survive. However, of the few gymnosperms that do resprout,

all are components of crown-fire regimes, in which aboveground mortality is nearly certain (Keeley and Zedler 1998).

*The genus Pinus is an outstanding example in which fire clearly is the driving force for thick bark (Keeley and Zedler 1998). This radiation very likely began in the Cretaceous and continued through the Tertiary (Millar 1998), suggesting fire was an important ecosystem

process throughout these periods.

The human era : Fire in the preindustrial world

*Early hominids (genus Homo) appeared in eastern Africa about 2.5 mya, and fire has been closely integrated into many stages of their evolution. It is believed that the rise of Homo

erectus from its more primitive ancestors was fueled by the ability to cook—that is, to use fire (Wrangham et al. 1999). Recent studies demonstrate a preference by nonhuman primates for cooked food (Wobber et al. 2008). The higher food energy that cooking supplies, as well as the detoxifying effects of heating (which increased the diversity of available food), contributed to a fitness advantage in these early humans.

*Furthermore, cooking implied a delay in food consumption, which required the development of social abilities for the distribution of tasks within the group (e.g., collection, accumulation,

cooking, defense, even stealing), as well as the socializing effect of gathering around nighttime campfires (Pyne 1995). 

*There is evidence of the controlled use of fire by Homo erectus in Africa (clusters of ancient hearths) during the Lower Pleistocene (James 1989), about 1.5 MaBP. 

*The earliest noncontroversial evidence out of Africa is from the Near East during the Early-

Middle Pleistocene (0.79 mya; Goren-Inbar et al. 2004). 

During the Paleolithic and Mesolithic ages, fire was used extensively for what has been termed `fire-stick farming' (Bird et al. 2008). This term implies using fire for a variety of activities to change human habitats and environments. For instance, fire-stick farming by Australian Aborigines created fine-grained landscape mosaics with greater small-animal diversity and increased hunting productivity (Bird et al. 2008). 

*Fire-stick farming was probably necessary after the megafauna extinction, not only to open up closed-canopy woodlands to create habitable environments but also to reduce catastrophic fires that would pose a risk to humans (Burney and Flannery 2005), and to increase seed resources needed as humans were forced to switch to a less meat-dependent diet.

*The Neolithic agricultural revolution required fire to alter the natural vegetation from perennial-dominated to annual dominated landscapes. It has been postulated that people

preferred to live in fire-prone places because the burning provided them advantages for hunting, foraging, cultivating, and livestock herding (Pyne 1995). 

*Charcoal evidence suggests monotonic increases of biomass burning from the last glacial maximum (about 21,000 years BP) up to the start of the agricultural stage (about 10,000 year BP; figure 3), and this trend is linked to climatic warming and the expansion of terrestrial vegetation as a result of the waning of ice sheets (Power et al. 2008).

*This upward tendency in global fire activity was halted with the rise of agriculture, although a marked regional variation in charcoal accumulation has been observed for this period.

人類と火に関して(著者に)興味深い話をここに二つあげる(つぎつぎと連歌のように知的話題が連鎖発展するような対話を愉しむ機会がこの頃あるだろうか．Triviaを楽しむのとは違うのである).

＊人口と文化の維持(タスマニアでの火をおこす技術の喪失): 読者は文化喪失に関するある種の危機意識が本書にはあると感じているだろう．タスマニアのように隔離された小さな人口では，たとえば火をおこす技術さえ喪失するというのは興味深い事実である(ただし，この事実をきちんと記述した文献を実見していない: 孫引きならT. Flannery,  The Future Eaters: an Ecological History of the Australasia Lands and People  (Grove Press, New York, 2002). 

　　今後は人口が多いからその心配はないというのはかなり単純に過ぎる．より高度な技術については長い養成期間を要するような人員が必須でその個体数は必然的に極めて少なくなりうる．マヤの文字文化を想起せよ．あるいは、次の引用 参照:

中国の伝統的数学は基本的には金や南宋，それから元の時代まで，特に代数学，つまり方程式をどうやって立て，数値的に解くかということに関しては当時世界では一番進んでいた(註: 天元術)のですが，それが明の時代になると全部忘れ去られてしまう． [上野健而+黒川信重「数学者達の到達点, 和算から現代数学まで」現代思想 2009/12 p68 上野の発言]

＊火を使い出す前とあとでわれわれと共生するバクテリアに大きな変化があったのではないか．新石器革命に関してはそのようなことがいわれている:

Mira et al., The  Neolithic revolution of bacterial genomes 

Trends Microbiol.  14 200 (2006)

Dramatic genomic changes have been identified in bacteria that are associated with large and stable human communities, agriculture and animal domestication: three features unequivocally linked to the Neolithic revolution.

 ついでながら，今後の温暖化のもとで環境に火災がいかに作用するか重要だと思われているが，よくわかっていない．大規模地球モデルの重要な不確定要素の一つである．

9 Bowman  Fire in the Earth System 

S 324 481 (2009)

To manage fire may become more difficult in the future as climate change alters fire regimes. This risk is difficult to assess, however, because fires are still poorly represented in global models.

関連した論文はいろいろ出てきているが，たとえば

Ravi Can biological invasions induce desertification?

Garbage In, Gospel Out

9 W Willinger, D Alderson, and J C. Doyle 

Notices AMS 56, 586 (2009).

Measurement based Internet research (phenomenology!)

“we illustrate why and how in the case of the Internet, scale-free network models of the preferential attachment type have become a classic lesson in how errors of various forms occur and can add up to produce results and claims that create excitement among non-networking researchers, but quickly collapse under scrutiny with real data or when examined by domain experts.” “ we motivate here the development of a novel modeling approach for Internetlike systems that 

(1) respects the highly designed nature of the network; 

(2) reflects the engineering intuition that exists about a great many of its parts;

(3) is fully consistent with a wide range of measurements; and 

(4) outlines a mathematical agenda that is more challenging, more relevant, and ultimately more rewarding than the type of mathematics motivated by an alluring but largely misguided approach to Internet modeling based on scale-free graphs of the preferential attachment type.”

“Ask not what mathematics can do for [the Internet]; ask what [the Internet] can do for mathematics.” (Ulam)

Foremost among these issues are the dangers of taking available data “at face value” without a deeper understanding of the idiosyncracies and ambiguities resulting from domain-specific collection and measurement techniques.

＊No amount of number crunching or mathematical sophistication can extract knowledge we can trust from low-quality data sets, whether they are of petabyte scale or not.