Exoplanet biosignatures: understanding oxygen as a biosignature in the context of its environment
We describe how environmental context can help determine whether oxygen (O2) detected
in extrasolar planetary observations is more likely to have a biological source. Here we …
in extrasolar planetary observations is more likely to have a biological source. Here we …
Integrated genomic and fossil evidence illuminates life's early evolution and eukaryote origin
Establishing a unified timescale for the early evolution of Earth and life is challenging and
mired in controversy because of the paucity of fossil evidence, the difficulty of interpreting it …
mired in controversy because of the paucity of fossil evidence, the difficulty of interpreting it …
Phosphorylation on the early earth
Phosphorus is an element critical to the formation of several biomolecules, including nucleic
acids, the energy transfer molecule ATP, and phospholipids. It hence lies at the heart of …
acids, the energy transfer molecule ATP, and phospholipids. It hence lies at the heart of …
The geologic time scale
Construction and assembly of the Geologic Time Scale involves:(a) constructing a relative
(chronostratigraphic) standard scale for key periods in the Earth's rock record;(b) identifying …
(chronostratigraphic) standard scale for key periods in the Earth's rock record;(b) identifying …
Carbon isotope composition of organic compounds produced by abiotic synthesis under hydrothermal conditions
Although it is widely believed that production of organic compounds by Fischer–Tropsch
synthesis and related processes occurs in many geologic environments, unambiguous …
synthesis and related processes occurs in many geologic environments, unambiguous …
Rare earth elements (REE) and yttrium in stream waters, stream sediments, and Fe–Mn oxyhydroxides: fractionation, speciation, and controls over REE+ Y patterns in …
We have collected∼ 500 stream waters and associated bed-load sediments over an∼
400km2 region of Eastern Canada and analyzed these samples for Fe, Mn, and the rare …
400km2 region of Eastern Canada and analyzed these samples for Fe, Mn, and the rare …
Reassessing the evidence for the earliest traces of life
The isotopic composition of graphite is commonly used as a biomarker in the oldest (> 3.5
Gyr ago) highly metamorphosed terrestrial rocks. Earlier studies on isotopic characteristics …
Gyr ago) highly metamorphosed terrestrial rocks. Earlier studies on isotopic characteristics …
An estimate of the deepest branches of the tree of life from ancient vertically evolving genes
Core gene phylogenies provide a window into early evolution, but different gene sets and
analytical methods have yielded substantially different views of the tree of life. Trees inferred …
analytical methods have yielded substantially different views of the tree of life. Trees inferred …
Raman spectroscopy: analytical perspectives in mineralogical research
It is said that during a voyage to Europe in the summer of 1921, the Indian physicist
Chandrasekhara Venkata Raman (1888–1970) looked at the wonderful blue opalescence of …
Chandrasekhara Venkata Raman (1888–1970) looked at the wonderful blue opalescence of …
Cycling phosphorus on the Archean Earth: Part II. Phosphorus limitation on primary production in Archean ecosystems
Several lines of evidence point to low rates of net primary production (NPP) in Archean
oceans. However, whether Archean NPP was limited by electron donors or nutrients …
oceans. However, whether Archean NPP was limited by electron donors or nutrients …