At the moment we have no direct evidence for water once being on the surface of Venus. On Mars we can see tantalizing evidence of ancient shorelines, and it’s possible we might be able to discover some on Venus, too, although much of the Venus we see today has been reshaped by volcanic activity about 700 million years ago, hiding evidence of an ancient ocean. But if it had water, and a habitable environment, then it’s not impossible it had life too.
“Both planets [Earth and Venus] probably enjoyed warm liquid water oceans in contact with rock and with organic molecules undergoing chemical evolution in those oceans,” study co-author David Grinspoon from the Planetary Science Institute in Arizona told New Scientist. “As far as we understand at present, those are the requirements for the origin of life.”
Given that Venus may have remained habitable for at most 2 billion years, it’s unclear if complex life could have arisen in that time. On Earth, for comparison, it took almost 3 billion years for complex life to take shape. But the idea is an interesting one.
Much more research is needed before we can come to a conclusion. But who knows – what is now regarded as Earth’s hellish evil twin may once have been much more friendly.