52
4 Life Evolves
and chemistry – and life. Life changes the composition of the atmosphere, and the
biosphere transforms, as Lovelock puts it, in the flexible Gaian way of adapting to
change and converting a murderous intruder into a powerful friend. The environment of the young alien Earth was suitable for the earliest life, and the environment
of the transformed planet became suitable for those living now.
An ardent environmentalist, Lovelock (2007) is worried about global warming,
lest we must turn into thermophiles, but advocates nuclear energy as a replacement
for fossil fuels. He notes that the Chernobyl exclusion zone became a paradise for
wildlife, more tolerant to radiation than to human intrusions. Indeed, Gaia is versatile. The Earth may turn out to become optimal for other varieties of life. Luxurious
jungles flourishing in the global greenhouse? Cyborgs? Soft robots? A sure forecast
is that microbes will survive in any case. The romantic notion of Gaia – Earth as a
self-regulating system tuned to supporting life may be as metaphoric as the Biblical
account of Genesis, but we must care for our Earth even if she does not care for us.
4.4 Cells Are Sine Qua Non
A life-like form has to be separated from the environment. This is necessary even
when it cannot yet be called properly alive. A chemical reactor must have an envelope preventing its contents from dissolving or uncontrollably escaping in another
way, and only needs inputs and outputs to bring in fresh reactants and expel degraded waste. The essence of degradation is decreasing the free energy (Sect. 2.5).
Engineers need to maintain a chemical reactor in a stationary state, continuously
producing the desired product at the expense of free energy from the environment,
and therefore a well-defined and guarded border is necessary. Compare it with border controls preventing (in some countries) immigrants from entering and (in countries of another kind) citizens from escaping: a chemical reactor needs both.
Fig. 4.6 A micelle
The same with life, starting with the
grey period between chemistry and life.
A modest addition to Eigen’s essentials of life, function and information
(Sect. 4.2), is a membrane enclosing
a private space where these essentials
reside. Such an enclosure could have
emerged quite easily, and the idea put
forward by Oparin (1924) was that cells
came first, and chemical metabolism
was initiated within these enclosures.
Among the chaotic ingredients of the
primordial organic matter, there were
probably some Janus-faced chemicals,
with polar heads preferring water attached to hydrocarbon chains preferring their own company or their likes. Common
4 Life Evolves
and chemistry – and life. Life changes the composition of the atmosphere, and the
biosphere transforms, as Lovelock puts it, in the flexible Gaian way of adapting to
change and converting a murderous intruder into a powerful friend. The environment of the young alien Earth was suitable for the earliest life, and the environment
of the transformed planet became suitable for those living now.
An ardent environmentalist, Lovelock (2007) is worried about global warming,
lest we must turn into thermophiles, but advocates nuclear energy as a replacement
for fossil fuels. He notes that the Chernobyl exclusion zone became a paradise for
wildlife, more tolerant to radiation than to human intrusions. Indeed, Gaia is versatile. The Earth may turn out to become optimal for other varieties of life. Luxurious
jungles flourishing in the global greenhouse? Cyborgs? Soft robots? A sure forecast
is that microbes will survive in any case. The romantic notion of Gaia – Earth as a
self-regulating system tuned to supporting life may be as metaphoric as the Biblical
account of Genesis, but we must care for our Earth even if she does not care for us.
4.4 Cells Are Sine Qua Non
A life-like form has to be separated from the environment. This is necessary even
when it cannot yet be called properly alive. A chemical reactor must have an envelope preventing its contents from dissolving or uncontrollably escaping in another
way, and only needs inputs and outputs to bring in fresh reactants and expel degraded waste. The essence of degradation is decreasing the free energy (Sect. 2.5).
Engineers need to maintain a chemical reactor in a stationary state, continuously
producing the desired product at the expense of free energy from the environment,
and therefore a well-defined and guarded border is necessary. Compare it with border controls preventing (in some countries) immigrants from entering and (in countries of another kind) citizens from escaping: a chemical reactor needs both.
Fig. 4.6 A micelle
The same with life, starting with the
grey period between chemistry and life.
A modest addition to Eigen’s essentials of life, function and information
(Sect. 4.2), is a membrane enclosing
a private space where these essentials
reside. Such an enclosure could have
emerged quite easily, and the idea put
forward by Oparin (1924) was that cells
came first, and chemical metabolism
was initiated within these enclosures.
Among the chaotic ingredients of the
primordial organic matter, there were
probably some Janus-faced chemicals,
with polar heads preferring water attached to hydrocarbon chains preferring their own company or their likes. Common