coacervate theorya theory expressed by the Russian biochemist A.I. Oparin in 1936 suggesting that the origin of life was preceded by the formation of mixed colloidal units called ‘coacervates’. These are particles composed of two or more colloids which might be protein, lipid or nucleic acid. Oparin proposed that whilst these molecules were not living, they behaved like biological systems in the ancient seas. They were subject to natural selection in terms of constant size and chemical properties, there was a selective accumulation of material and they reproduced by fragmentation. Subsequent work by the American biochemists Stanley Miller and Harold Urey shows that such organic materials can be formed from inorganic substances under the conditions prevailing on the prebiological earth. They synthesized amino acids by passing a spark through a mixture of simple gases in a closed system.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005