Life 2016, 6(1), 6; doi:10.3390/life6010006
Review
Evolutionary Steps in the Emergence of Life Deduced from the Bottom-Up Approach and GADV Hypothesis (Top-Down Approach)
Kenji Ikehara 1,2
1 G & L Kyosei Institute, Keihannna Labo-401, Hikaridai 1-7, Seika-cho, Sorakugun, Kyoto 619-0237, Japan; Tel./Fax: +81-774-73-4478
2 International Institute for Advanced Studies of Japan, Kizugawadai 9-3, Kizugawa, Kyoto 619-0225, Japan
Academic Editors: David Deamer, Bruce Damer and Niles Lehman
Received: 1 November 2015 / Accepted: 18 January 2016 / Published: 26 January 2016
Abstract
It is no doubt quite difficult to solve the riddle of the origin of life. So, firstly, I would like to point out the kinds of obstacles there are in solving this riddle and how we should tackle these difficult problems, reviewing the studies that have been conducted so far. After that, I will propose that the consecutive evolutionary steps in a timeline can be rationally deduced by using a common event as a juncture, which is obtained by two counter-directional approaches: one is the bottom-up approach through which many researchers have studied the origin of life, and the other is the top-down approach, through which I established the [GADV]-protein world hypothesis or GADV hypothesis on the origin of life starting from a study on the formation of entirely new genes in extant microorganisms. Last, I will describe the probable evolutionary process from the formation of Earth to the emergence of life, which was deduced by using a common event—the establishment of the first genetic code encoding [GADV]-amino acids—as a juncture for the results obtained from the two approaches.
Keywords: origin of life; [GADV]-protein world; GADV hypothesis; pseudo-replication; protein 0th-order structure
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