Early life on Earth and beyond may have been ocean dwellers

[Admin]

The genetic tree of life suggests that the first life on Earth may have lived underwater, shielded from harmful ultraviolet light from the sun.

Early life on Earth and beyond may have been ocean dwellers : Read more

 

[rod]

What happened to the Faint Young Sun problem here and frozen water all over? Mars is even worse situation.

 

[rod]

Interesting how early life evolved without DNA or cells to *spectrally tuned* features in use. As the space.com report states, "By studying the genetic tree of life, scientists have determined that the first life on Earth may have lived underwater, where it would be shielded from harmful ultraviolet light from the sun."

I note this from the paper cited in the abstract, Earliest Photic Zone Niches Probed by Ancestral Microbial Rhodopsins, https://academic.oup.com/mbe/article/39/5/msac100/6582242?login=false

"Our results suggest that ancestral microbial rhodopsins likely acted as light-driven proton pumps and were spectrally tuned toward the absorption of green light, which would have enabled their hosts to occupy depths in a water column or biofilm where UV wavelengths were attenuated. Subsequent diversification of rhodopsin functions and peak absorption frequencies was enabled by the expansion of surface ecological niches induced by the accumulation of atmospheric oxygen. Inferred ancestors retain distinct associations between extant functions and peak absorption frequencies."

So, there is *spectrally tuned* features in the *genetic tree of life*. This past report indicates early life on Earth did not have DNA or cells.

Imagining early Earth as an exoplanet can help us search for alien life, scientists say, https://forums.space.com/threads/im...s-search-for-alien-life-scientists-say.55999/

"But through his research on evolution, Goldman and collaborators are trying to understand scenarios by which life may arise. Today's life, he says, is cellular and based on DNA, but neither cells nor DNA were present in the earliest forms of life on Earth. By association, "these were things that had to evolve in early evolutionary history," he said."

Starting with early life on Earth with no DNA and no cells, evolving to *spectrally tuned* features, looks like an interesting evolutionary problem in origin science.

 

[Unclear Engineer]

There is also the current bacteria that live underground, getting their energy from the chemicals created by ionizing radiation interacting with chemicals in rocks. Maybe that could have happened billions of years ago in rocks that were just wet, without any solar energy at all. Radioactivity in the early Earth was higher than today, too. So, I am wondering if life can initiate and evolve even where there are no "oceans", just water trapped under the surface.