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Evidencia de vida en la Tierra antes de hace 3.800 millones de años
S J Mojzsis1, G Arrhenius, K D McKeegan
1Scripps Institution of Oceanography, University of California San Diego, La Jolla 92093-0220, USA. smojzsis@ucsd.edu
Nature
|November 7, 1996
Resumen
La evidencia sugiere que la vida surgió en la Tierra hace al menos 3.800 millones de años. El análisis geoquímico de rocas antiguas revela isótopos ligeros de carbono, indicativos de actividad biológica, anteriores a la evidencia de microfósiles.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- Paleobiología Paleobiología.
- Ciencias de la Tierra Temprana Ciencias de la Tierra Temprana.
Sus antecedentes:
- El momento exacto del origen de la vida en la Tierra sigue siendo desconocido.
- Los microfósiles proporcionan evidencia de la vida temprana, pero a menudo se destruyen en antiguas rocas metamorfoseadas.
- Las firmas geoquímicas en minerales resistentes son cruciales para encontrar evidencia de actividad biótica temprana.
Objetivo del estudio:
- Investigar la evidencia geoquímica para el surgimiento de la vida antes de hace 3,500 millones de años.
- Para analizar la composición de isótopos de carbono en antiguos granos de apatita.
- Para determinar si los procesos abióticos podrían explicar las firmas isotópicas observadas.
Principales métodos:
- Mediciones de microsondas iónicas de la composición de isótopos de carbono.
- Análisis de las inclusiones carbonáceas dentro de los granos de apatita.
- Examen de antiguas formaciones de hierro en bandas del oeste de Groenlandia y la isla de Akilia.
Principales resultados:
- El carbono en las inclusiones dentro de los granos de apatita de 3.800 millones de años de antigüedad y potencialmente más antiguos es isotópicamente ligero.
- Esta ligera firma de carbono es indicativa de actividad biológica.
- Ningún proceso abiótico conocido puede explicar la composición isotópica observada y su incorporación selectiva en la apatita.
Conclusiones:
- Los hallazgos proporcionan evidencia de la aparición de la vida en la Tierra hace al menos 3.800 millones de años.
- Los datos geoquímicos desafían las suposiciones anteriores basadas únicamente en registros microfósiles.
- Es posible que se necesite más investigación para descartar procesos abióticos desconocidos.
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