Breathing room for early animals

Fischer, Woodward W.

doi:10.1073/pnas.1525100113

Cited by 7 publications

(2 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This suggests that more environments could be suitable for aerobic life than previously recognized. The topic of the expanded range of environments habitable for aerobes has primarily been discussed in the context of Earth history (e.g., Fischer, 2016;Zhang et al, 2016) and low O 2 environments on modern Earth (e.g., Ulloa et al, 2012), but it also has broad relevance to a range of planetary environments, including those on Mars, Europa, and elsewhere.…”

Section: O 2 On Earthmentioning

confidence: 99%

“…Recent efforts to understand the minimum O 2 concentrations necessary to support sponges and other basal animals have demonstrated survival and growth under surprisingly low O 2 concentrations, down to about 1% PAL (Sperling et al, 2013a;Mills et al, 2014). While these values are still much higher than the minimum O 2 concentrations for bacterial respiration (Stolper et al, 2010;Zakem and Follows, 2017), they greatly extend the spatial and temporal range of environments habitable for animals (e.g., oxygen minimum zones and Proterozoic oceans, e.g., Sperling et al, 2013b;Fischer, 2016;Zhang et al, 2016) and are an important new constraint in thinking about O 2 as a requirement and biosignature of complex life on other planets.…”

Section: O 2 On Earthmentioning

confidence: 99%

See 1 more Smart Citation

Follow the Oxygen: Comparative Histories of Planetary Oxygenation and Opportunities for Aerobic Life

et al. 2019

Self Cite

View full text Add to dashboard Cite

Aerobic respiration-the reduction of molecular oxygen (O 2) coupled to the oxidation of reduced compounds such as organic carbon, ferrous iron, reduced sulfur compounds, or molecular hydrogen while conserving energy to drive cellular processes-is the most widespread and bioenergetically favorable metabolism on Earth today. Aerobic respiration is essential for the development of complex multicellular life; thus the presence of abundant O 2 is an important metric for planetary habitability. O 2 on Earth is supplied by oxygenic photosynthesis, but it is becoming more widely understood that abiotic processes may supply meaningful amounts of O 2 on other worlds. The modern atmosphere and rock record of Mars suggest a history of relatively high O 2 as a result of photochemical processes, potentially overlapping with the range of O 2 concentrations used by biology. Europa may have accumulated high O 2 concentrations in its subsurface ocean due to the radiolysis of water ice at its surface. Recent modeling efforts suggest that coexisting water and O 2 may be common on exoplanets, with confirmation from measurements of exoplanet atmospheres potentially coming soon. In all these cases, O 2 accumulates through abiotic processes-independent of water-oxidizing photosynthesis. We hypothesize that abiogenic O 2 may enhance the habitability of some planetary environments, allowing highly energetic aerobic respiration and potentially even the development of complex multicellular life which depends on it, without the need to first evolve oxygenic photosynthesis. This hypothesis is testable with further exploration and life-detection efforts on O 2-rich worlds such as Mars and Europa, and comparison to O 2-poor worlds such as Enceladus. This hypothesis further suggests a new dimension to planetary habitability: ''Follow the Oxygen,'' in which environments with opportunities for energy-rich metabolisms such as aerobic respiration are preferentially targeted for investigation and life detection.

show abstract

Section: O 2 On Earthmentioning

confidence: 99%