THE ORIGIN OF LIFEISTOCK,^SCIENCEPHOTO^ LIBRARYNEED TO KNOW
by TOM IRELAND (@Tom_J_Ireland)
Tom is a journalist and managing editor
at the Royal Society of Biology.Key terms to help
you understand the
origin of lifeABIOGENESIS
The technical term for life
originating from non-living
matter, such a s simple organic
chemicals. The opposite,
biogenesis, means living matter
arising from other living matter,
which is how life on E ar th
proliferated once it s t ar ted.RNA WORLD
RNA is like a single-stranded
version of DNA and performs
many important functions in all
living cells. Scientis t s have
shown that RNA can
spontaneously form a
self-replicating molecule,
suggesting Earth was once
populated by simple
self-replicating RNA forms.PROTON GRADIENT
Cells can only function properly
with energy created by complex
metabolic reactions, which
generate a difference in
chemical charges in different
parts of the cell. This is known
as a proton gradient. Working
out how it could occur
spontaneously is a key part
of establishing how early
life functioned.LUCA
The Last Universal Common
Ancestor is the ancient
organism from which all life on
Earth is thought to have
evolved. It is a largely
theoretical organism, thought
to have lived around 3.5 billion
years ago, just before cells split
into bacteria and archaea.PANSPERMIA
The idea that life evolved after
travelling to Earth from space.solution is achievable. Increasingly,
scientists are using computer
modelling to investigate how certain
mixtures of molecules might behave
over time – an advance that could help
speed up progress in t his a rea. “I don’t
think I’m that far away...” says Dr
Lane, semi-seriously.
“The key message is that the nuts
and bolts of all life is almost identical,”
says Dr Matthew Powner, a chemist
studying t he origin of life at University
College London. “The difference
between us and a tree seems obvious,
but people often don’t understand how
similar the biochemistry that it’s all
built from is, using very few chemical
species. Eight nucleotides, 20 amino
acids and a few lipids, and you don’t
need much else.”
The overall solution may not have
been solved yet, but each and every
life-like molecule that emerges from
a laboratory is another piece of the
puzzle found. As broadcaster a nd
geneticist Dr Adam Rutherford
concludes in his book Creation:
The Origin of Life, “That first time had
millions of yea rs, whereas scientists
have made these replicators in a
decade... In all origin-of-life studies
it is impor ta nt to remember t hat we
know the answer: life is the answer.
The question is finding a believable
route to get there.”Present day
There are estimated to be at least 10 million species
of organism living on Earth today, but the vast
majority are still unknown to scientists. The human
population is over seven billion, and mankind is
now exploring space for signs of other life.
Dr Nick Lane, a biochemist and
author of the origin-of-life book The
Vital Question, says the problem is
even ha rder to solve t ha n t hose posed
by theoretical physics. “We are not
even in the position of the physicists,
where everyone at least agreed what
the question was and could build a
huge machine like CER N to look for
the answer. We are still miles away
from that agreement.”
However, despite the lack of a
unifying theory, many scientists
remain confident that a satisfactoryResearchers are
increasingly investigating
RNA as a key candidate
for helping life to evolve