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Theme 15

Evolution of Life and Astrobiology

Simon Poulton, Newcastle,
David T. Johnston, Harvard,

Co-hosted sessions

SESSIONS

15a. Water, elements and life in early-Earth and Mars analogs

(co-hosted by Themes 15 and 2)

Co-convenors:
Long Li (University of Toronto) - longligeology.utoronto.ca
Lori Ziolkowski (McMaster University) - lorizedgmail.com
Nadia Mykytczuk (McGill University) - nadia.mykytczukmcgill.ca

Investigations of early-Earth and Mars analogs on the Earth are the most accessible way to gain insights into the origin and evolution of life on the early Earth and to direct the search for life on other planets, such as Mars. This session aims to bring together the most recent advancements in our understanding of water sources, element cycles, life forms, and life-rock interactions in analog environments by experimental, field, and theoretical approaches using molecular, biomarker, spectroscopic, elemental and isotopic tools.

Keynote speaker:
John C. Priscu (Montana State University), jpriscumontana.edu
Invited speakers:
Barbara Sherwood Lollar (University of Toronto), bslollarchem.utoronto.ca
Christopher Omelon (University of Texas-Austin), omelonmail.utexas.edu

15b. The molecular foundations of geochemical and microbial co-evolution

(co-hosted by Themes 15, 2, and 16)

Co-convenors:
Alexander Bradley (Washington University) – bradleyfas.harvard.edu
Eric Collins (McMaster University) - collroymcmaster.ca, rec3141gmail.com
Boswell Wing (GEOTOP-McGill University) – boswell.wingmcgill.ca

Microbes evolve. Microbial metabolic pathways redistribute elements and isotopes in ways that have changed through Earth history. Some of these evolutionary events have left distinct geochemical traces in the rock record, and served to help calibrate the timing of microbial evolution. Microbial evolution has repeatedly perturbed biogeochemical cycles, creating a feedback that alters the chemical environment under which selection occurs. Understanding the process of microbial evolution may therefore help us arrive at a richer understanding of the evolution of the Earth's surface and the geochemical record. In this session, we invite contributors from across the biogeochemical spectrum to address microbial origination, selection and extinction, as well as their relationship to environmental evolution. Contributions that take novel geochemical or biological approaches are particularly welcome.

Keynote speaker:
David T. Johnston (Harvard University), johnstoneps.harvard.edu

15c. (Bio)geochemistry in terrestrial hyperarid environments: a pathway to understanding the surface chemistry of Mars

(co-hosted by Themes 15 and 16)

Co-convenors:
W. Andrew Jackson (Texas Tech University) - andrew.jacksonttu.edu
Alfonso F. Davila (NASA Ames Research Center) - adavilaseti.org

CANCELLED

15d. Between the O₂ steps: life and the environment between the GOE and the Late Neoproterozoic rise of ice and animals

Co-convenors:
Noah Planavsky (University of California, Riverside) - planavskygmail.com; nplan001ucr.edu
Timothy Lyons (University of California, Riverside) - timothylucr.edu
Peter McGoldrick (University of Tasmania) - P.McGoldrickutas.edu.au

In contrast to what we have for the Phanerozoic and Archean, there are very few constraints on atmospheric oxygen levels during the mid-Precambrian (2.3 Ga–0.75 Ga). And although new and refined models are emerging for Proterozoic ocean chemistry, our understanding of the spatiotemporal fabric of ocean redox remains similarly nascent. These details become particularly important in light of hypothesized environmental throttles that challenged the early evolution of eukaryotes. In this session we will explore geochemical and biological co-evolution from the Great Oxidation Event in the early Paleoproterozoic to the onset of widespread glaciation in the Neoproterozoic. We welcome contributions using wide ranging observational, analytical, and numerical approaches. We also encourage submissions addressing Archean trends and phenomena that presage the GOE, as well as diverse Cryogenian and Ediacaran themes linked to late Neoproterozoic oxygenation.

Keynote speaker:
Lee Kump (Penn State University), lkumppsu.edu

15e. 40 Years of Gaia

(co-hosted by Themes 15 and 2)

Co-convenors:
Colin Goldblatt (University of Victoria, Canada) - czguvic.ca
Andrew Watson FRS (University of East Anglia, UK) - a.watsonuea.ac.uk

The Gaia Hypothesis - first published by James Lovelock in 1972 - brought a paradigm shift in the geosciences. It proposes that life has actively regulated the planetary environment to facilitate its own existence. Whilst the degree of regulation that has occurred remains controversial, Gaia spurred new thinking in how life interacted with all parts of the Earth. Today, the pervasive influence of life is recognised everywhere on Earth, from the atmosphere to the mantle, and the importance of life in shaping Earth's evolution is undeniable. The modern field of "Earth System Science" has emerged to describe the co-evolution of life and its environment. In this session, we invite contributions relating to any aspect of Gaia including, but not limited to, the development of Gaia hypothesis/theory, co-evolution of life and the environment, description of environmental homoeostasis by life, the regulation of planetary climate, implications for anthropogenic change and implications for astrobiology.

Keynote speaker:
Tim Lenton (University of Exeter, UK), T.M.Lentonexeter.ac.uk

15f. Organic sulfur in the Earth System

Co-convenors:
William Gilhooly (Indiana-Purdue) - wgilhooliupui.edu
Josef Werne (University of Minnessota) - jwerned.umn.edu
Alon Amrani (Hebrew University) - alon.amranimail.huji.ac.il

SESSION MERGED with 16c

15g. Geochemical, mineralogical, and morphological biosignatures in astrobiology

Co-convenors:
Dominic Papineau (Boston College) - dominic.papineaubc.edu
Andy Czaja (University of Wisconsin - Madison) - aczajageology.wisc.edu

This session invites contributions that investigate signatures of past or present life in rocks from Earth and beyond. Studies of microbial remains and their by-products in ancient and modern environments by means of geochemical, mineralogical, and morphological biosignatures have provided an increasingly sophisticated understanding of the early evolution of life and the diversification of metabolic pathways. Such studies are critical to make informed assessments of the potential for life on extraterrestrial bodies and to develop means for detection. A critical aspect of establishing robust biosignatures, however, involves the identification of non-biological processes and their reaction products that could be misinterpreted as being biological in origin. Recent work centered on the development of state-of-the-art micro-analytical techniques (e.g., Raman spectroscopy, SIMS, FIB-SEM, TEM, EBSD, LA-ICPMS, and STXM) has provided greater spatial resolution to help sort out such issues. The development of these techniques for the study of geochemical, mineralogical, and morphological biosignatures central to astrobiology will pave the way for the study of extraterrestrial samples, either in situ or returned.

Keynote speaker:
George Cody (Carnegie Institution of Washington), codygl.ciw.edu

Co-hosted sessions:

Please note that for abstract submission purposes, the following sessions and their respective descriptions appear in their primary Theme assignments (numbers in red or before the title).

7f.- Critical zone processes: their role in ecology and evolution

Co-convenors: Elisabeth Bui/CSIRO, Australia and Martin Goldhaber/USGS
(co-hosted by Themes 7, 12 and 15)

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