宇宙での生命の起原と進化
山岸明彦
東京薬科大学生命科学部

Are we alone in the universe?
生命は、宇宙で我々だけか？

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アストロバイオロジー• 天文学• 惑星科学、地球物理学• 地球化学、化学進化• 地学的証拠• 生化学的研究• 熱水地帯の微生物生態• 遺伝子の証拠、分子進化学• 宇宙での微生物探査• 知的生命体探査

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何を検出して生物と言うか• 生物の定義
複製する：現場培養、現場観察境界を持つ：蛍光染色Live and dead代謝する：酵素活性染色4生命の定義とDarwinism
山岸明彦

生命と地球の歴史 磯﨑・丸山• ある種の境あるいはしきりをもって、周囲の外世界から独立した空間を保持する。

• 外界から物質やエネルギーを取り込んだり放出したりする代謝を行う• 自己複製を行う（繁殖する）• 世代交代を通して進化するアストロバイオロジー 小林憲正
• 代謝をおこなう• 自己複製を行う• 外界との境界をもつ• 進化（変異）する•（江上不二夫）

Darwin 1859, p 5• As many more individuals of each species areborn than can possibly survive; and as,
consequently, there is a frequently recurring
struggle for existence, it follows that any being, if
it vary however slightly in any manner profitable
to itself, under the complex and sometimes
varying conditions of life, will have a betterchance of surviving, and thus be naturally selected.
From the strong principle of inheritance, any
selected variety will tend to propagate its new andmodified form.[Darwin 1859, p 5]

Darwinism（ウォーレス現代生物学）• 生物の多産• 限られた資源• 変異の存在• 最適者の生存• 自然選択G. Joyce: Forward for Origins of Life (1993)• There is no single definition that satisfies theentire scientific community.
• Exobiology Program with in the NASA
• Life is a self-sustained chemical system capable ofundergoing Darwinian evolution.
• Darwinian evolution:– Self-reproduction,– Material community over an historical lineage,– Genetic variation,– Natural selection.

G. Joyce: Forward for Origins of Life (1993)• Life is a self-sustained chemical system:– Living systems contain all the genetic informationnecessary for their own constant production (i.e.,metabolism)

Definition of Life: PICERAS
Koshland 2002 Science 295: 2215-2216
Fundamental principles on which a living system isbased.
• Program: recorded by DNA• Improvisation:即興でやること: mutation• Compartmentalization: maintain concentration• Energy: movement of chemicals• Regeneration: re-synthesis, cell division, birth• Adaptability: respond immediately• Seclusion: 隔離 of reactions, information's

Definition:• Suppe 1977 The structure of ScientificTheories– Necessary conditions– Sufficient conditions• Nietssche– There are concepts that can be defined, whereas
others only have a history.

Maturana and Verela 1981, Autopoiesis and Cognition-theRealization of the Living• Autopoietic system:– Entity defined by an internal processes of self-maintenanceand self-generation.
– the process whereby an organization produces itself. An
autopoietic organization is an autonomous and selfmaintaining unity which contains component-producing
processes. The components, through their interaction,
generate recursively the same network of processes which
produced them. An autopoietic system is operationallyclosed and structurally state determined with no apparent
inputs and outputs. A cell, an organism, and perhaps acorporation are examples of autopoietic systems.

A. Lazcano, 2008, Chemistry andBiodiversity, vol 5. 1-15
• Life could be defined as a self-sustaining
chemical system that is capable ofundergoing Darwinian evolution.
• The properties associated with living
systems, such as replication, selfassemblage, or catalysis are also found in
nonliving entities.

Pross, A. 2011 J. Systems Chem.
2, 1-14• Toward a general theory of evolution:
Extending Darwinian theory to inanimate
matter• 非生物的反応で競争選択されるシステムへDarwinismを拡張する。
• Dynamic kinetic stability (DKS)• 川の水• 生命はより大きなDKSへ向かう• 予言不可能だが、合目的的（？山岸）Pross, A. 2011 J. Systems Chem.
2, 1-14• Toward a general theory of evolution:
Extending Darwinian theory to inanimate
matter• Evolution: Certain oligomeric replicating
systems, through a process of imperfect
replication and on-going kinetic selection,
will tend to evolve toward replicating
systems of greater DKS.

Pross, A. 2011 J. Systems Chem.
2, 1-14• Toward a general theory of evolution:
Extending Darwinian theory to inanimatematter• One whose replicating reaction would havebeen strictly governed by thermodynamic
constraints, was transformed into a far
from-equilibrium energy-gathering
teleonomic replicating system. (Origin ofLife)

生命の定義• 無いという考えもある。歴史的に定義される。あるいは、説明される。
• NASAの定義と限界• 日本での理解• 現在も研究対象である。
• 生物はシステム：その要素は生きている– 次章参照
• 自由エネルギー• 動的平衡生命とは何か（シュレディンガー）• 負のエントロピー• 自由エネルギー（第６章への注）

参考文献• Joyce, G.F., 1993: Climbing Darwin’s ladder, Curr. Biol.
3, 703-704.
• Daniel E. Koshland Jr., 2002: The Seven Pillars of Life,295, 2215-2216• Frederick Suppe , 1977: The Structure of scientifictheories, University of Illinois Press• Maturana, H. R. and F. J. Varela, 1981: Size constancy andaccommodation. Perception 10: 707-709,• A. Lazcano, 2008: What Is Life? A Brief Historical
Overview, CHEMISTRY & BIODIVERSITY , 5, 1-15
• Pross, A. 2011: Toward a general theory of evolution:
Extending Darwinian theory to inanimate matter, 2, 1-1421