University of Wollongong University of Wollongong
Research Online Research Online
Faculty of Science, Medicine and Health -
Papers: part A
Faculty of Science, Medicine and Health
1-1-2016
Rapid emergence of life shown by discovery of 3,700-million-year-old Rapid emergence of life shown by discovery of 3,700-million-year-old
microbial structures microbial structures
Allen Phillip Nutman
University of Wollongong, University of New South Wales
, anutman@uow.edu.au
Vickie C. Bennett
Australian National University, University of New South Wales
, vickie.bennett@anu.edu.au
Clark R. L Friend
Glendale, UK
, crlfriend@yahoo.co.uk
Martin J. Van Kranendonk
University of New South Wales
, m.vankranendonk@unsw.edu.au
Allan Chivas
University of Wollongong
, toschi@uow.edu.au
Follow this and additional works at: https://ro.uow.edu.au/smhpapers
Part of the Medicine and Health Sciences Commons, and the Social and Behavioral Sciences
Commons
Recommended Citation Recommended Citation
Nutman, Allen Phillip; Bennett, Vickie C.; Friend, Clark R. L; Van Kranendonk, Martin J.; and Chivas, Allan,
"Rapid emergence of life shown by discovery of 3,700-million-year-old microbial structures" (2016).
Faculty of Science, Medicine and Health - Papers: part A
. 4157.
https://ro.uow.edu.au/smhpapers/4157
Research Online is the open access institutional repository for the University of Wollongong. For further information
contact the UOW Library: research-pubs@uow.edu.au
Rapid emergence of life shown by discovery of 3,700-million-year-old microbial Rapid emergence of life shown by discovery of 3,700-million-year-old microbial
structures structures
Abstract Abstract
Biological activity is a major factor in Earth's chemical cycles, including facilitating CO2 sequestration and
providing climate feedbacks. Thus a key question in Earth's evolution is when did life arise and impact
hydrosphere-atmosphere-lithosphere chemical cycles? Until now, evidence for the oldest life on Earth
focused on debated stable isotopic signatures of 3,800-3,700 million year (Myr)-old metamorphosed
sedimentary rocks and minerals1,2 from the Isua supracrustal belt (ISB), southwest Greenland3. Here we
report evidence for ancient life from a newly exposed outcrop of 3,700-Myr-old metacarbonate rocks in
the ISB that contain 1-4-cm-high stromatolites-macroscopically layered structures produced by microbial
communities. The ISB stromatolites grew in a shallow marine environment, as indicated by seawater-like
rare-earth element plus yttrium trace element signatures of the metacarbonates, and by interlayered
detrital sedimentary rocks with cross-lamination and storm-wave generated breccias. The ISB
stromatolites predate by 220 Myr the previous most convincing and generally accepted multidisciplinary
evidence for oldest life remains in the 3,480-Myr-old Dresser Formation of the Pilbara Craton, Australia4,5.
The presence of the ISB stromatolites demonstrates the establishment of shallow marine carbonate
production with biotic CO2 sequestration by 3,700 million years ago (Ma), near the start of Earth's
sedimentary record. A sophistication of life by 3,700 Ma is in accord with genetic molecular clock studies
placing life's origin in the Hadean eon (>4,000 Ma)6.
Keywords Keywords
emergence, life, shown, discovery, rapid, 3, structures, 700, million, year, old, microbial
Disciplines Disciplines
Medicine and Health Sciences | Social and Behavioral Sciences
Publication Details Publication Details
Nutman, A. P., Bennett, V. C., Friend, C. R. L., Van Kranendonk, M. J. & Chivas, A. R. (2016). Rapid
emergence of life shown by discovery of 3,700-million-year-old microbial structures. Nature, 537 (7621),
535-538.
This journal article is available at Research Online: https://ro.uow.edu.au/smhpapers/4157
Rapid emergence of life shown by discovery of 3700 million year old 1
microbial structures 2
3
Allen P. Nutman
1,5
, Vickie C. Bennett
2,5
, Clark R. L. Friend
3
, Martin J. Van Kranendonk
4,5,6
4
& Allan R. Chivas
1
5
6
1
GeoQuEST Research Centre, School of Earth & Environmental Sciences, University of 7
Wollongong, Wollongong, NSW 2522, Australia 8
2
Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, 9
Australia, 10
3
Glendale, Tiddington, Oxon, OX9 2LQ, UK 11
4
School of Biological, Earth and Environmental Sciences, University of New South Wales 12
Australia, Kensington, NSW 2052, Australia 13
5
Australian Centre for Astrobiology, University of New South Wales Australia, Kensington, 14
NSW 2052 Australia 15
6
Australian Research Council Centre of Excellence for Core to Crust Fluid Systems 16
17
18
Biological activity is a major factor in Earth's chemical cycles, including facilitating 19
CO
2
sequestration and providing climate feedbacks. Thus a key question in Earth’s 20
evolution is when did life arise and impact hydrosphere-atmosphere-lithosphere 21
chemical cycles? Until now, evidence for the oldest life on Earth focused on debated 22
stable isotopic signatures of 3,800-3,700 million-year-old (Ma) metamorphosed 23
sedimentary rocks and minerals
1,2
from the Isua supracrustal belt (ISB), southern West 24
Greenland
3
. Here, we show new evidence for ancient life from a newly-exposed outcrop 25
of 3,700 Ma metacarbonate rocks in the ISB that contain 1-4 cm high stromatolites - 26
macroscopically layered structures produced by microbial communities. The ISB 27
stromatolites grew in a shallow marine environment, as indicated by seawater-like rare 28
earth element + yttrium trace element signatures of the metacarbonates, and by 29
interlayered detrital sedimentary rocks with cross-lamination and storm-wave 30
generated breccias. The ISB stromatolites predate by 220 million years the previous 31
most convincing and generally accepted multidisciplinary evidence for oldest life 32
remains in the 3,480 Ma Dresser Formation of the Pilbara Craton, Australia
4,5
. The 33
presence of the ISB stromatolites demonstrates the establishment of shallow marine 34
carbonate production with biotic CO
2
sequestration by 3,700 Ma, near the start of 35
Earth’s sedimentary record. A sophistication of life by 3,700 Ma is in accord with 36
genetic molecular clock studies placing life’s origin in the Hadean (>4,000 Ma)
6
. 37
38
Stromatolites are broadly defined as sedimentary structures that are produced by 39
microorganism communities through trapping and binding of sediment, and/or precipitation 40
of carbonate
7
. Stromatolites are the most persistent evidence of life in Earth history, and are 41
known from the present (e.g., Shark Bay, Western Australia) to 3,480 million years ago (Ma) 42
in the rock record
4,5
. 43
Little deformed and weakly metamorphosed 3,480-3,350 Ma sedimentary rocks from the East 44
Pilbara Terrane of the Pilbara Craton (Western Australia) contain the oldest convincing 45
evidence for life on Earth in the form of domical and coniform stromatolites
5,8
. In these cases, 46
a biological origin for stromatolites is supported by morphology
8
, stable isotope signatures
9
, 47
seawater-like trace element signatures of the dolomitic host rocks
10
and the presence of 48
microfossils
11
. Early life environments in the Pilbara Craton included shallow marine and 49
emergent sedimentary settings, as well as thermal springs. This variety of environments, 50
combined with a diversity of stromatolite forms within individual units, indicates that by 51
3,480 Ma the biosphere was already diverse, and thus life must have originated significantly 52
earlier
12
. 53
The search for even earlier life is confounded by the scarcity of Eoarchaean (>3,600 Ma) and 54
Hadean (>4,000 Ma) rocks and the strong deformation and high grade metamorphism (500-55
750°C) that affected them. In most localities this has eliminated primary features within these 56
rocks (‘primary’ here means structures pertaining to the formation of the protolith, prior to 57
superimposed metamorphism)
3
. This is a particular problem in the search for signs of early 58
life in carbonate rocks, due to the propensity of carbonates to undergo ductile deformation 59
and recrystallise as marble during metamorphism and orogeny. Consequently, the search for 60
evidence of life in Eoarchaean rocks has focussed on chemical signatures, such as the 61
isotopic compositions of carbon (as graphite) and iron from metasedimentary rocks, but the 62
origin of these signatures is not unique and their significance as evidence of ancient life 63
remains debated
,2,13,14,15
. Most isotopic searches for the oldest evidence of life have targeted 64
the Isua supracrustal belt (ISB) of southern West Greenland, because it contains by far the 65
largest areal extent of diverse Eoarchaean metasedimentary rocks with rare, small areas of 66
low deformation in which primary sedimentary structures are preserved
16
. 67