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

  title={Evidence for life on Earth before 3,800 million years ago},
  author={Stephen J. Mojzsis and Gustaf Arrhenius and Kevin D. McKeegan and T. Mark Harrison and Allen P. Nutman and Clark R.L. Friend},
IT is unknown when life first appeared on Earth. The earliest known microfossils (˜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 argued1,2. But the known examples of crustal rocks older than ˜3,500 Myr have experienced intense metamorphism, which would have obliterated any fragile microfossils contained therein. It is… 

Geochemical evidence for terrestrial ecosystems 2.6 billion years ago

Data show that the organic matter in some Au/U-rich conglomerates and ancient soils of 2.3-Gyr age very probably represents remnants of microbial mats that developed on the soil surface between 2.6 and 2.7 Gyr ago, which places the development of terrestrial biomass more than 1.4 billion years earlier than previously reported.

The origin of life from a paleontological perspective, a review

Although the origin of life cannot be dated with precision, life must have appeared soon after the cooling of the Earth, when the existence of liquid water on the planet enabled primitive oceans to

A fresh look at the fossil evidence for early Archaean cellular life

The rock record provides unique evidence for testing models as to when and where cellular life first appeared on Earth, but its study, however, requires caution and critical analysis of morphospace and context is needed.

The Geological Context for the Origin of Life and the Mineral Signatures of Fossil Life

Life arose in a very different environment compared to that of the modern Earth. Unfortunately we have very little direct evidence of the conditions of the young Earth because of plate-tectonic

Origin of life from apatite dating?

It is concluded that, about 1,500 Myr ago, these apatites in Akilia island experienced a metamorphic event of about 600 °C (estimated by the closure temperature of the U-Pb system), which is consistent with measurements of 1,600-1,700 Myr for Rb-Sr mineral isochrons on biotites and 1,670 Myr for K-Ar muscovite from Amitsog gneiss in the region.

Reassessing the evidence for the earliest traces of life

It is shown that graphite occurs abundantly in secondary carbonate veins in the ISB that are formed at depth in the crust by injection of hot fluids reacting with older crustal rocks (metasomatism); these metasomatic rocks, which clearly lack biological relevance, were earlier thought to be of sedimentary origin.

Morpho- and Chemo-Fossil Evidence of Early Life

This chapter summarizes what is known about the timing of the emergence of life on Earth from the morpho- and chemo-fossil (chemical and isotopic signals remaining from the decomposition of living

Reassessing evidence of life in 3,700-million-year-old rocks of Greenland

Three-dimensional analysis of the morphology and orientation of the structures within the context of host rock fabrics, combined with texture-specific analyses of major and trace element chemistry, show that the ‘stromatolites’ are more plausibly interpreted as part of an assemblage of deformation structures formed in carbonate-altered metasediments long after burial.

3 Early Life on Earth and Analogies to Mars

The evidence for early life and its initial evolution on Earth is linked intimately with the geological evolution of the early Earth. The environment of the early Earth would be considered extreme by



Carbon isotope evidence for early life

The Letter by Mojzsis et al. on evidence for life on Earth before 3,800 million years ago was accompanied by a discussion of the effects of prograde thermal metamorphism on carbon isotope ratios that contained errors that contributed to the conclusion that it would have been physically impossible for such a process to produce the observed δ^(13)C values.

Early Archaean Age for the Isua Iron Formation, West Greenland

SOME 150 km north-east of Godthaab, on the edge of the inland ice cap, a refolded syncline of mainly basic rocks containing banded ironstones and other rocks of supracrustal origin is enclosed by

Sedimentary facies of iron-formation

The sedimentary iron-formations of Precambrian age in the Lake Superior region can be divided on the basis of the dominant original iron mineral into four principal facies: sulfide, carbonate, oxide,

A 3,800-million-year isotopic record of life from carbon in sedimentary rocks

An increased ratio of 12C to 13C, an indicator of the principal carbon-fixing reaction of photosynthesis, is found in sedimentary organic matter dating back to almost four thousand million years

Microfossils of the Early Archean Apex Chert: New Evidence of the Antiquity of Life

It is established that trichomic cyanobacterium-like microorganisms were extant and morphologically diverse at least as early as ∼3465 million years ago and suggests that oxygen-producing photoautotrophy may have already evolved by this early stage in biotic history.