The origin of life may have had a contribution from endogenous [1] and/or exogenous sources [2,3]. The early Earth was heavily bombarded by comets, asteroids and meteorites 4.6 to 3.8 billion years ago, just before life originated in our planet [2,3]. Comets contain some of the building blocks of life and their precursors. For example, glycine, methylamine and ethylamine were detected in comet 81P/Wild-2 [4,5]. The impact of comets and asteroids into the Earth may have also led to the formation of organic molecules [2, 6-8]. It was experimentally shown that the impact-shock of a typical cometary ice mixture produces several a-amino acids, including a-aminoisobutyric acid (a-AIB), isovaline and racemic mixtures of alanine (D/L~1) [8]. A class of meteorites named carbonaceous chondrites contain up to 5% of organic carbon per weight [9] and have also several building blocks of life in its soluble fraction [10-12]. The analysis of the organic content of comets, asteroids and meteorites gives crucial information about the resources available on the early Earth, which may have been used by the first living organisms.[1] Cleaves and Lazcano (2009) In Chemical Evolution II: From Origins of Life to Modern Society. Oxford University Press, pp. 17. [2] Chyba et al. (1990) Science 249, 366. [3] Chyba and Sagan (1992) Nature 355, 125. [4] Glavin et al. (2008) MAPS 43, 399. [5] Elsila et al. (2009) MAPS 44, 1323. [6] Anders (1989) Nature 342, 255. [7] Furukawa et al. (2009) Nature GeoScience 2, 62. [8] Martins et al. (2013) Nature Geoscience 6, 1045. [9] Alexander et al. (2013) GCA 123, 244. [10] Sephton (2002) NPR 19, 292. [11] Martins et al. (2008) EPSL 270, 130. [12] Martins and Sephton (2009) In Amino acids, peptides and proteins in organic chemistry, Wiley-VCH Verlag GmbH & Co. KGaA, pp. 1.

Exogenous contribution of comets, asteroids, and meteorites for the origin of life

248th National Meeting (2014)

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