Resolving the History of Life on Earth by Seeking Life As We Know It on Mars

TL;DR

This paper explores the hypothesis that life on Earth may have originated on Mars through a cyanosulfidic process, and discusses how Mars missions could provide evidence to support or refute this idea, offering insights into planetary evolution and life's origins.

Contribution

It proposes a plausible chemical pathway for life's origin on Mars and highlights the potential of Mars rover missions to test this hypothesis, bridging planetary science and origins of life research.

Findings

Mars' crust could have facilitated prebiotic chemistry more effectively than early Earth.

Transient habitable environments on Mars may have enabled life transfer to Earth.

Mars missions can provide critical evidence to confirm or refute a Martian origin of life.

Abstract

An origin of Earth life on Mars would resolve significant inconsistencies between the inferred history of life and Earth's geologic history. Life as we know it utilizes amino acids, nucleic acids, and lipids for the metabolic, informational, and compartment-forming subsystems of a cell. Such building blocks may have formed simultaneously from cyanosulfidic chemical precursors in a planetary surface scenario involving ultraviolet light, wet-dry cycling, and volcanism. However, early Earth was a water world, and the timing of the rise of oxygen on Earth is inconsistent with final fixation of the genetic code in response to oxidative stress. A cyanosulfidic origin of life could have taken place on Mars via photoredox chemistry, facilitated by orders of magnitude more sub-aerial crust than early Earth, and an earlier transition to oxidative conditions. Meteoritic bombardment may have generated transient habitable environments and ejected and transferred life to Earth. The Mars 2020 Perseverance Rover offers an unprecedented opportunity to confirm or refute evidence consistent with a cyanosulfidic origin of life on Mars, search for evidence of ancient life, and constrain the evolution of Mars' oxidation state over time. We should seek to prove or refute a Martian origin for life on Earth alongside other possibilities.