Discovering the Early Dominance of Purple Microorganisms on Earth: Scientists Unveil New Biosignatures for Astronomers Seeking Life Beyond Our Planet

In a new study, scientists have discovered that purple microorganisms may have dominated early Earth. These microorganisms, including purple archaea, use a molecule called retinal for photosynthesis and could have been the dominant lifeforms on our planet before the presence of oxygen. This research expands the potential lifeforms that could have existed on our planet according to Shiladitya DesSarma, a molecular biologist at the University of Maryland and lead author of the study.

In another development, researchers have added spectral data on 20 species of purple bacteria found in various environments such as marshes and deep-sea hydrothermal vents. The scientists analyzed the wavelengths of light reflected by these bacteria and created models to predict how these patterns would appear on a distant planet. The resulting collection of light signatures is being added to a public database for use by other researchers in their projects.

Astronomers search for life on other planets using biosignatures, which can include the color of a planet’s surface. Reflected light spectroscopy is a technique used to observe these biosignatures, but current telescopes like the James Webb Space Telescope are limited in their abilities. While these telescopes can detect gases in an exoplanet’s atmosphere, they cannot measure the reflected light from the planet’s surface. Edward Schwieterman, an astronomer at the University of California Riverside, notes that advancements in observing technologies are necessary to analyze the surface features of distant planets for potential signs of life.