Belief and Darwin

Natural selection as expounded by Charles Darwin has formed the basis of my understanding of life on Earth. Indeed, Darwin’s approach of observation, experiment and interpretation has been my scientific mantra. I do not exclude a creator, after all Darwin only discovered natural selection, he did not invent it.

With this in mind imagine my pride in 2009 in being asked by one of the leading biochemistry review journals to contribute something in celebration of the bicentenary of Darwin’s birth.

I wrote, Darwin, natural selection and the biological essentiality of aluminium and silicon, published by Trends in Biochemical Sciences (TIBS) in 2009. I might easily argue that this is my finest written contribution to science. The article borrows from Darwin’s natural selection to explain in the clearest terms why neither aluminium nor silicon alone are essential to life and yet combined as aluminosilicate they are why we have the life we have on Earth today.

In essence aluminium has no essential role in life today because it has been excluded from biochemical evolution by silicon. The absence of this exclusion mechanism early doors in biochemical evolution (natural selection) would not have precluded life on Earth only the life dominated by oxidative metabolism that we benefit from today. Such a conclusion leads us inextricably to the question as to what then follows when the advent of the aluminium age counteracts the exclusion mechanism that heralded the life we have today.

Contrary to the highly reactive aluminium, silicon has no essential role in life today because of an almost complete lack of biological chemistry. I have written many times in Dr’s Newsletter on this subject including the post embedded below.

Silicic Acid: The Maker's Forgotten Gift

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May 14, 2025

I have mused multiple times in Dr’s Newsletter over the incredulous and life-giving properties of Nature’s secret, silicic acid. Just use ‘silicic acid’ as your search term under my posts and you will find at least thirty relevant posts.

In writing my seminal piece for TIBS (please ask if you would like the pdf) I needed to include a figure of some sort to illustrate my ideas. Once again and somewhat cheekily I borrowed an idea from Darwin, his iconic ‘Tree of Life’ sketch with the words ‘I think’ scrawled in the top left hand corner.

I am copying Exley’s Tree of Life figure for you below.

The figure is clearly somewhat fanciful and yet I believe it to have scientific credibility and potentially predictability. Below is the text I used to explain the diagram back in 2009.

‘ A biochemical tree of life for the natural selection of aluminium. Concomitant with the emergence of higher forms of life are significant concentrations of environmental silicic acid and commensurate insignificant concentrations of biologically reactive aluminium. Silicic acid limits the biological availability of aluminium, and it is unable to compete with Mg(II), Ca(II), Fe(II/III) for binding by phosphate, carboxylate and hydroxyl functional groups. Aluminium is excluded from inorganic biochemistry.

Subsequently over tens of millions of years and, recently concomitant with the activities of modern human beings*, an increase in the concentration of biologically reactive aluminium occurs. This increase, coincident now and in the foreseeable future with evolutionarily-driven lower levels of environmental silicic acid, displaces essential metals from biomolecules which are integral to vital biochemical processes. Aluminium is now competitive and has become an active participant in biochemical evolution. What then are the implications of such for future biochemistry?

*The Aluminium Age

Key: Degree of shading indicates changes through evolutionary time in the environmental concentrations of biologically reactive (i) silicic acid ([Si(OH)4]B; blue) and (ii) aluminium ([Al]B; red). The extent of coloured branches and their variously-shaped leaves estimates the major metal ion competitors for Al(III) and their preferred functional groups for binding respectively. mya: million years ago.’

Charles Darwin’s ‘Tree of Life’ began the explanation of why we are here and why all life is here with us.

Exley’s ‘Tree of Life’ begins the explanation of why humans will not survive the aluminium age unless we address the iatrogenic increase in the biological availability of aluminium.

We still have time, I think!