VACCINE

CellPress Nucleus
Mitochondria & Metabolism
Volume 34, Issue 12, p589–593, December 2009
Darwin, natural selection and the biological essentiality of aluminium and silicon
by Christopher Exley
The Birchall Centre, Lennard-Jones Laboratories, Keele University, Staffordshire, ST5 5BG, UK
Absract
If one was asked to produce a set of ‘Trump Cards’ based upon ‘Forces of
Nature Defining Life on Earth’ then which card would be ‘Top Trump’? I was recently
chastised on the Darwin Today website for suggesting Darwin and ‘natural
selection’ rather than, for example, Newton and ‘gravity’. Although there is no
denying the significance of gravity, my argument in favour of natural selection is
simply that gravity is just one factor that contributes towards an outcome which
ultimately is defined by natural selection. Both the beauty and the brilliance of
natural selection are reflected in its omnipotence to explain the myriad observations
of life and, as I will affirm herein, its explanation of the biological essentiality
of aluminium and silicon is no exception.
Together they constitute a form of homeostasis with aluminium being retained
both physically and chemically in myriad forms and each form being capable of
acting as a sink or source of labile and potentially biologically reactive aluminium.
It is always important to emphasise that there is no evolutionarily directed
or conserved biology to enable aluminium homeostasis and so this non-essential
but highly biologically reactive metal cation is at the whim of the predominant
or pre-eminent chemistry of any particular environment [8] [9]. This unpredictability
makes biologically available aluminium a concern for all forms of life on
Earth [2].
In this year, 200th anniversary of the birth of Charles Darwin and the 150th anniversary
of the publication of On the Origin of Species, a UK scientist has used
Darwin’s seminal work on Natural Selection in helping to define the biological
essentiality of the second (silicon) and third (aluminium) most abundant elements
of the Earth’s crust.
The lack of any clear or significant biological essentiality for both of these elements
is a mystery as all other abundant elements of the Earth’s crust are known
to be biologically essential.
Dr Chris Exley, Reader in Bioinorganic Chemistry at Keele University and a
world authority on the ways in which aluminium impacts upon life on Earth, says
natural selection is often interpreted as ‘survival of the fittest’ but what is often
not appreciated is that the selection processes themselves are niche driven, which
means that those characteristics which convey fitness in one environment may not
convey fitness in another, perhaps adjacent, environment or niche. This is both
the strength and the beauty of natural selection and it can be applied to cellular
biochemistry as it is applied to speciation of organisms.
Aluminium is biologically reactive, while silicon is biologically inert. Natural
selection informs us that the non-essentiality of aluminium is explained by its
non-participation in biochemical evolution due to a complete lack of its biologically
reactive forms.
On the other hand the biologically available form of silicon (silicic acid) has been
extremely abundant throughout biochemical evolution and its biological essentiality
has been dictated by its extremely limited biological reactivity.
It is no coincidence that one of the very few reactions of silicic acid is that with
aluminium and that this reaction protects against the toxicity of aluminium.
An essential role of silicon throughout biochemical evolution has been to keep
aluminium out of life! However, the activities of humans in learning how to extract
aluminium from its ores and using it in myriad ways in what is now the
Aluminium Age means that Earth’s inherent protection against the toxicity of aluminium
is being compromised and that biologically reactive aluminium is now an
active participant in biochemical (and hence human) evolution.
Some of the early results of the arrival of biochemically reactive aluminium have
been worryingly obvious, including the death of fish and trees in geographical
regions impacted by acid deposition, whereas others, and perhaps those which
in particular are linked with the human condition, might yet be too subtle to be
directly attributable to the participation of biologically-reactive aluminium in the
natural selection of the elements of biological essentiality.
Link: I can’t provide a link for this report and I’m certain that this is not the complete
report. The text above consists of excerpts found in other reports that reference
this one using a variety of internet search terms. The complete document
requires purchase:
“This unpredictability
makes biologically
available aluminium
a concern for all forms
of life on Earth.”
http://www.cell.com/trends/biochemical-sciences/abstract/S0968-0004(09)00167-4?_returnURL=http%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0968000409001674%3Fshowall%3Dtrue