SPECIAL REPORT
The
Chemistry
of Ι*ίϊ5?
The feasibility of performing s i m p l e laboratory ex periments to study the origin of life was first reported by Stanley Miller in 1953. Miller, a first-year graduate student at the University of Chicago, convinced Harold Urey they s h o u l d perform e x p e r i m e n t s to test Urey's idea that life originated in a reducing atmosphere on p r i m i t i v e Earth. Miller successfully produced a m i n o acids from a mixture of m e t h a n e , a m m o n i a , h y d r o g e n , and water vapor by passing an electric discharge through it. Since then, a m u l t i t u d e of e x p e r i m e n t s have d e m o n s t r a t e d the formation of a m i n o acids and other organic c o m p o u n d s by subjecting simulated p r i m i t i v e Earth at mospheres to a variety of energy sources. We are n o w at a watershed in the laboratory s t u d y of the origin of life. The s y n t h e s i s of a m i n o acids and the other s i m p l e m o n o m e r s essential for life has been investigated extensively. Emphasis n o w has shifted to the question of the formation of polymers. Studies on the prebiotic s y n t h e s i s of biological p o l y m e r s are fa cilitated not o n l y by the w e a l t h of laboratory data obtained over the past 30 years but by progress in other areas. For example, the c o n d i t i o n s under w h i c h life p r o b ably originated are better understood as a consequence of our exploration of the solar s y s t e m . The time scale for chemical e v o l u t i o n and the origin of life has been better d e f i n e d from studies of fossilized microorgan isms and ancient rocks. Mathematical theories for the formation and e v o l u t i o n of p o l y m e r i c species can be evaluated as a c o n s e q u e n c e of advances in c o m p u t i n g capability. The s h o t g u n approach to e x p e r i m e n t a t i o n that w a s appropriate w h e n the s t u d y of chemical e v o l u t i o n w a s in its infancy is b e i n g replaced w i t h ex p e r i m e n t s that are more precisely a i m e d to a n s w e r vuqust 27, 1984 C&EN
Origin James P. Ferris, Rensselaer Polytechnic Institute •• • specific q u e s t i o n s concerning the chemical e v e n t s l e a d i n g to the origin of life. It is important first to define "life" so that the es sential characteristics of a l i v i n g system can be dif ferentiated from that of other arrays of m o l e c u l e s . I find the criteria proposed by Norman H o r o w i t z of California Institute of Technology to be most helpful: Life possesses the properties of replication, catalysis, and mutability. I consider any chemical system that possesses these three properties to be l i v i n g . The central problem of the origin of life is h o w structures w i t h the properties of replication, catalysis, and mutation formed on Earth. This is basically a chemical problem that can be s u b d i v i d e d into three stages: the synthesis of m o n o m e r s such as amino acids and n u c l e o t i d e s from hydrocarbons, h y d r o g e n cya nide, cyano c o m p o u n d s , a l d e h y d e s , and ketones; the polymerization of these m o n o m e r s under the reaction c o n d i t i o n s that may have existed on primitive Earth;
Many atoms, ions, and molecules have been detected in space Comets
Titan
Hydrocarbons CH, CH
, CH4, HC 2 t HCJJH,
HC2CH3
OH, HgO, CH 3 OH, C2H5OH
C, C + , CH, CH+, C2, C3
CH4, C^He* C3H8, O1H4, C2H2, HC==CC==CH, CH3C^=CH
C1 to C20 aliphatic, alicyclic, and aromatic compounds
O, OH, OH+, H 2 O f H20+
H20, Ci to C4 alcohols
C, CO, CO+, HCO
C 2 to C 5 aldehydes and ketones, H
