Evolutionary events culminating in specific minerals becoming essential for life.

Abstract

The environment in which living organisms evolved was apparently a primary determinant of which elements became essential for life. The first organic materials and, ultimately, life forms most likely were formed in an ancient sea containing minerals that provided structural integrity and catalytic ability to the first complex organic substances. The site at which life began has been suggested to be at the edge of the sea near sediments, or around a hydrothermal system. The strongest circumstantial evidence supports a hyperthermophilic beginning. Regardless of the site, the biological importance of elements tends to parallel oceanic abundance, but in higher forms of life this parallelism apparently has been mitigated by a natural selection process that resulted in some elements becoming more important because of their superior abilities over other elements to perform vital functions. The converse to biological importance is that toxicity of elements and oceanic abundance tends to be inversely related. The basis for this relationship may be that the efficiency of homeostatic mechanisms to cope with a high intake of a specific element probably reflects upon the exposure of an organism to the element during its evolution. Thus, a study of evolutionary events may be helpful in predicting and comprehending the essential and toxic nature of mineral elements in humans.