Home' Teacher : May 2010 Contents 30 TEACHER MAY 2010
ting of blood, involve dozens of reactions
and scores of convergent genetic evolution
required for the process to work at all. A
phrase known as 'irreducible complexity' is
frequently used, usually followed by smug
looks from those questioning evolution and
extensive eye rolling by those who are faith-
ful evangelists of Darwin.
Molecular biology in the examination of
replication from the simplest bacteria to the
cells of dolphins, chimpanzees and hu mans
is also putting the screws on evolution-
ary mechanisms down to the very level of
deoxyribonucleic acid or DNA replication.
It appears that evolutionary mechanisms
Let me try to make a relatively complex
everyday phenomenon simple.
Right now, as you're reading this, you
have cells in your body that are being
replaced through cell division. Your DNA
is like a rubber band twisted on itself -- a
twist on a twist on a twist, six times, actu-
ally. To copy this, it needs to be prised apart.
It uses a chemical, called DNA polymerase
and also little 'machines,' called clamp pro -
teins, which hold the strand straight a little
bit at a time, while it's copied, before mov-
ing on to the next section.
Like all proteins, the blueprint is coded
by DNA and 'photocopied' using messenger
ribonucleic acid or mRNA. It's like mRNA
is transcribed from a DNA template, and
carries that DNA coding information to the
sites of protein synthesis: the ribosomes.
The previously proposed mechanism of
evolution was simply that mutations make
new and novel improvements to the genome,
despite the fact that the majority are either
deleterious or of no consequence, but here's
the-chicken-and-the-egg problem. You see,
even the simplest, most basic piece of bacte-
rial DNA can't be copied without the clamp
proteins, whose plans came from DNA. So
the very first strand of DNA replicating is
problematic,because it requiresbothenzymes
and clamp proteins coded from a pre-existent
DNA blueprint to start the process.
It seems to me that when evolution is
scrutinised by science it's afforded diplo -
matic immunity. Not even Schrodinger's
atomic model or Einstein's multiple con-
tributions to science are mandated in
Australian schools, but Darwin's theory,
founded in the pre-genetic era, is afforded
The now-defunct and debu nked phlo-
giston theory, which is little known outside
science history, has remarkable similarities
with evolutionary theory. The idea was that
there was a fiery substance called 'phlogis-
ton' in combustible bodies that was released
during combustion. It explained processes
like combustion and why -- before anyone
had identified something called carbon diox-
ide -- things lost weight when they burned.
Like evolution, it was a 'just so' story, but in
a matter of months, the work of both Joseph
Priestley and Antoinne Lavoisier showed
that this idea of matter giving off phlogiston
when burned was, well, just so much hot air,
really. In great scientific tradition, we hold
it as science history rather than science fact.
Not so with evolution.
The reality is that a new, honest, secular
debate is needed about evolutionary theory.
In the absence of a molecular mechanism for
the introduction of new and novel informa-
tion to the genome through random events,
we need to be scientifically honest with
ourselves. For almost 80 years now, we've
realised that, genetically, natural selection
occu rs, but results in a less diverse gene
pool, not a more rich and complex one. The
diversity evident now and through the fossil
record suggests that googolplexes of valu-
able additions to the genomes of every spe-
cies neededto occur to get anywhere near the
diversity and complexity of life we see today.
The machinery just ain't there, yet, with
faith akin to the most devout washers in
the Ganges, wailers at the wall and monks
in our abbeys, many scientists criticise the
naysayers. 'Have patience,' they say. 'It will
come. We will find the holy grail of the evo -
lutionary mechanism.' In truth, the hard
evidence for evolution may be unravelling
like a cheap sweater.
It's important that we address the dis-
proportionate protection that we afford the
theory of evolution, possibly out of some
misplaced Christophobia, by allowing the
rational process of scientific criticism to
deal with discrepancies in the data. That's
something that happens to every theory in
science, and those theories are the better for
it. Our current understanding of the atom,
electricity, mechanics, gravity and genetics
have all benefitted from intelligent debate,
yet the door appears to be closed on debate
about the theory of evolution.
Oh, and that sound? That's just me casu-
ally opening a can, which may well be filled
to the brim with worms that may or may
not have evolved from amoeba after all.
Mick Wilkinson teaches Che mistry at
Northside Christian College, Brisbane.
Seelke, R. & B. Oke mwa . (2008). Studies
on the e volution ary potential of trpA
mutants of Escherichia coli. Prese nted
at the 68th annual meeting of the North
Central Branch of the Americ an Society
for Microbiology, 17-18 October, St.
Seelke, R. & S. Ebnet. (2007). An
unexpectedly low evolutionary pote ntial
for a trpA 49V,D60N double mutant
in Esche richia coli. Presented at the
107th Annual Meeting, Abstract R-055,
Americ an Society for Microbiology,
Toronto, Can ada, 21-25 May.
Lohm an, T.M & K.P Bjornson. (1996).
Mechanism s of helicase- c atalysed DNA
unwinding. Annu al revie w of bioche mis-
Marians, K.J. (1992). Proc aryotic
DNA replic ation . Annual Review of
ACARA's consultation period for the draft
Australian Curriculum runs until 23 May,
with the fin al curriculum expected to
be available to be taught in Australian
schools from 2011. Visit the consultation
portal that hosts the draft curriculum at
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