Aluminum is the third most abundant element in the Earth’s crust and the most abundant metal (Exley 2003). Aluminum is neither required by biological systems nor is it known to participate in any essential biological processes. While today all living organisms contain some aluminum, there is no scientific evidence that any organism uses aluminum for any biological purpose. There is similarly no evidence from the proteome or genome that any organism has utilized aluminum at any time in the evolutionary record. Aluminum’s abundance and paradoxical lack of biological function remains a biochemical enigma.

It is argued that aluminum’s absence from biochemical processes can be best explained in terms of its “historical” absence from biochemical evolution (Exley 2009a). In spite of its abundance in the Earth’s crust, aluminum was not biologically available for the greater part of biochemical evolution. It was not available to participate in the natural selection of the elements...