Minor elements and evolution.

Abstract

Minor elements such as molybdenum and iron are essential elements or “bioelements” for microorganisms, plants, and higher animals. However, chromium is not regarded as a bioelement in the same sense. This may be explained by their relative concentrations in the sea water. Molybdenum is the most abundant of the transition elements in sea water. Its participation in different oxido-reductases such as nitrogenase, nitrate reductase, and CO2 reductase of primitive bacteria could be related to its abundance. Good correlation can be found between the biological behaviour of different elements and their concentration in sea water. This suggests the hypothesis that the composition of the present sea water reflects that of the primeval sea water at the time of the evolution of these enzyme systems. A concentration in the sea of about 1~5 nM may be regarded as “critical”. Elements with concentrations in sea water above this critical concentration could influence early evolutionary events, and so became either essential elements or neutral elements; organisms evolved independently of trace elements with concentrations less than the critical concentration.