A new book on the origins of life caught my eye. The book,
“The Vital Question,”[1] suggests that a possible explanation
for the evolution of living activity lies in energy transfer. Obtaining energy
is essential for fueling living activity, and the evolutionary development of
mechanisms for obtaining increasing amounts of energy lies in the specialized
function of mitochondria. This idea of energy and specialized systems for
obtaining energy suggests that social/economic development of societies also
might be explained by the evolution of energy production and availability. I
excerpted this note from Matt Ridley’s review[2]
of Lane’s book.
Ridley’s Summary
Life uses information (stored in DNA) to capture energy
(which it stores in a chemical called ATP) to create order. Humans burn
prodigious amounts of energy — we generate about 10,000 times as much energy
per gram as the sun. The sun is hotter only because it is much bigger. We use
energy to create and maintain intricate cellular and bodily complexity, the
opposite of entropy, just as we do in the economy, where the harnessing of
power from burning fuel enables us to build skyscrapers and aeroplanes. But we
— and here “we” means all living creatures, including bacteria — have an
idiosyncratic way of trapping energy to make it useful. We pump protons across
lipid membranes.
During every second of your life you pump a billion trillion
protons across membranes in the thousand trillion mitochondria that live inside
your body. Mitochondria are the topic of recent parliamentary debates (about
“three-parent embryos”), the central characters in this book and the
descendants of bacteria. Their job is to oxidise carbon and hydrogen so as to
pump protons and fuel life.
In 2000 a new kind of alkaline, warm-water vent was found on
the ocean floor in the mid-Atlantic (it was dubbed the Lost City because of its
huge carbonate chimneys and towers), where protons diffuse across thin,
semi-conducting walls of iron, nickel and sulphur into minuscule pores, causing
organic molecules to accumulate and interact. This, Lane and others now think,
was how life got started some 4 billion years ago, inside these rocky pores,
where the natural proton gradients came by accident to drive the generation of
molecular complexity.
Archaea and Bacteria
It appears now in the beginning that two life forms emerged
with different chemistry sets. We call them bacteria and “archaea”, but they
both look like microbes. It was only when we read their genes that we realised
how different they were — one uses right-handed forms of lipids, the other
left-handed, for instance. For a staggering two billion years they were all
there was on this planet. They both had great biochemical diversity but small
size and structural simplicity.
So how did these two early life forms after 2 billion years
finally manage to merge into complex cells with nuclei? Biologists now think
evolution often occurs due to a sort of interpenetration of two forms, like a
symbiosis in which one form lives within another. So Lane thinks it possible
that a single archea engulfed a single bacterium to turn it into a specialized
energy generator. So the bacteria became mitochondria which in all life
forms still have their own genetic code today (we have 14 genes in ours).
Lane's insight was to realize that thanks to this division
of labour, the energy available per gene is hundreds of thousands of times
greater in a eukaryotic cell than in a bacterium.
So the (perhaps overgenealized) idea is that energy is the
key to understanding living systems, not genetics. Energy drives activity, and
so tracing the evolution of the ability to capture and use energy marks the
progress of life, and continuing up to human activity, it was the ability to
radically increase the energy available per worker that marked the Industrial
Revolution. We could look at the increase in energy available in a society and mark
its relative advancement.
Conclusion
Perhaps instead of Earth Day and bemoaning the depletion of resources, it might be more valuable to celebrate Energy Day since it is energy that has produced human development including better stewardship of the environment, resources, and people’s well-being. In the future, it is energy that will produce the wealth we need to combat the effects of global warming and help people advance out of povertycontrary to those who only see energy usage as destructive.
[1] Nick Lane, The
Vital Question: Why Is Life the Way It Is? (London: Profile Books, 2015).
[2] Matt Ridley, “The
Vital Question,” Matt Ridley, April 21, 2015, http://www.rationaloptimist.com/blog/the-vital-question.aspx.
