From Charles Q. Choi at LiveScience:
We know little about Earth’s surface temperatures for the first 4 billion years or so of its history. This presents a limitation into research of life’s origins on Earth and how it might arise on distant worlds.
Now researchers suggest that by resurrecting ancient enzymes they could estimate the temperatures in which these organisms likely evolved billions of years ago. The scientists recently published their findings in the journal Proceedings of the National Academy of Sciences. More.
The big challenge will likely be to keep implicit assumptions from skewing the findings:
Scientists estimate when ancient enzymes might have existed by looking at their closest living relatives of their host organism. The greater the number of differences in the genetic sequences of these relatives, the longer ago their last common relative likely lived.
This wouldn’t be the “molecular clock,” would it? See, for example, Major disparities between molecular divergence dates and fossil ages for birds
See also: Discovery of 7 times higher complexity of protein folding!
and
What we know and don’t know about the origin of life