==La atmósfera primitiva==
[[File:Miller-Urey.png|thumb|200px|Imagen Figura diseño del experimento de [[Stanley Miller|Miller]]-Urey experiment layout, showing the primitive atmosphere assumed by themque muestra la atmósfera primitiva asumida por ellos]]Theories of the origin of life initially assumed that the primitive atmosphere should be a reducing one in order to prevent oxidative destruction of the components of the Las teorías sobre el origen de la vida inicialmente asumieron que la atmósfera primitiva debería ser una reductora con el fin de prevenir la destrucción oxidativa de los componentes de la "sopa primordial soup".<ref>{{cite bookcita libro|authorautor=Aw, S. E|titletítulo=Chemical Evolution|publishereditorial=Master Books|locationubicación=San Diego, California|yearaño=1982|isbn=0-89051-082-2}}</ref> So the evolutionists theorize an early atmosphere without oxygen. [[Oparin]] believed that the Earth's early atmosphere was composed of hydrogen (H<sub>2</sub>), methane (CH<sub>4</sub>), ammonia (NH<sub>3</sub>) and [[water]] vapor (H<sub>2</sub>O), containing no oxygen.<ref name=how /> [[J. B. S. Haldane|Haldane]] postulated the same theory and his most important conclusions were presented in a short article for the ''Rationalist Annual''.<ref name=clark>{{cite book|author=Clark, Ronald W|title=J B S: The Life and Work of J. B. S. Haldane|publisher=Coward-McCann, Inc.|location=New York|year=1969|page=93-94|id=Library of Congress Catalog Card Number:68-11875}}</ref> Other scientists who corroborated this model of atmosphere were Miller and Urey. They reasoned that a small but significant amount of H<sub>2</sub> remained in the primordial atmosphere and reacted with atoms of carbon, nitrogen or oxigen forming this kind of atmosphere.<ref>{{cite book|author=[[Charles Thaxton|Thaxton, Charles B.]]; Bradley, Walter L.; Olsen, Roger L|title=The Mistery of Life's Origin: Reassessing Current Theories|publisher=Philosophical Library|location=New York|year=1984|page=74|isbn=0-8022-2447-4}}</ref> By sparking together hydrogen, methane, ammonia, and water vapor, they produced several amino acids, the building blocks of organic life.<ref>{{cite book|author=Smith, A. E. Wilder|authorlink=A. E. Wilder-Smith|title=The Creation of Life: A Cybernetic Approach to Evolution|publisher=Harold Shaw Publishers|location=Wheaton, Illinois|year=1970|page=49|isbn=0-87788-144-8}}</ref>
Nowadays there is almost universal agreement among specialists that the primitive atmosphere contained no reducing gases like methane, ammonia or hydrogen.<ref name=bydesign>{{cite book|author=Sarfati, Jonathan|authorlink=Jonathan Sarfati|title=[[By Design]]:Evidence for Nature's Intelligent Designer - the God of the Bible|publisher=Creation Book Publishers|location=Powder Springs, GA|year=2008|isbn=978-0-94990672-4}}</ref> Instead, it is that the atmosphere contained [[carbon dioxide]] and nitrogen.<ref name=bydesign /> According [[Hubert Yockey]], the modern view regarding the atmosphere of the early Earth is that it was neutral and composed of nitrogen (N<sub>2</sub>), carbon dioxide (CO<sub>2</sub>), water (H<sub>2</sub>O) and maybe some ammonia (NH<sub>3</sub>).<ref>{{cite book|author=Yockey, Hubert P|authorlink=Hubert Yockey|title=Information Theory, Evolution, and the Origin of Life|publisher=Cambridge University Press|location=Cambridge|year=2005|page=146|isbn=978-0-521-80293-2}}</ref>