Evidence for life on Earth before 3,800 million years ago

被引:803
作者
Mojzsis, SJ
Arrhenius, G
McKeegan, KD
Harrison, TM
Nutman, AP
Friend, CRL
机构
[1] WM KECK FDN CTR ISOTOPE GEOCHEM,DEPT EARTH & SPACE SCI,LOS ANGELES,CA 90095
[2] AUSTRALIAN NATL UNIV,RES SCH EARTH SCI,CANBERRA,ACT 0200,AUSTRALIA
[3] OXFORD BROOKES UNIV,DEPT GEOL & CARTOG,OXFORD OX3 0BP,ENGLAND
关键词
D O I
10.1038/384055a0
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
IT is unknown when life first appeared on Earth. The earliest known microfossils (similar to 3,500 Myr before present) are structurally complex, and if it is assumed that the associated organisms required a long time to develop this degree of complexity, then the existence of life much earlier than this can be argued(1,2). But the known examples of crustal rocks older than similar to 3,500 Myr have experienced intense metamorphism, which would have obliterated any fragile microfossils contained therein. It is therefore necessary to search for geochemical evidence of past biotic activity that has been preserved within minerals that are resistant to metamorphism. Here we report ion-microprobe measurements of the carbon-isotope composition of carbonaceous inclusions within grains of apatite (basic calcium phosphate) from the oldest known sediment sequences-a similar to 3,800-Myr-old banded iron formation from the Isua supracrustal belt, West Greenland(35), and a similar formation from the nearby Akilia island that is possibly older than 3,850 Myr (ref, 3). The carbon in the carbonaceous inclusions is isotopically light, indicative of biological activity; no known abiotic process can explain the data. Unless some unknown abiotic process exists which is able both to create such isotopically light carbon and then selectively incorporate it into apatite grains, our results provide evidence for the emergence of life on Earth by at least 3,800 Myr before present.
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页码:55 / 59
页数:5
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