The longevity of habitable planets and the development of intelligent life

TL;DR

This paper explores why intelligent life appears late on Earth, proposing that many planets have short habitable periods and that intelligent life development is a slow but likely process, improving SETI prospects.

Contribution

It introduces a new explanation for late intelligent life emergence, emphasizing brief habitable periods and slow evolution as common factors across planets.

Findings

Many planets have brief habitable periods.

Intelligent life development is a slow but probable process.

This enhances the likelihood of detecting extraterrestrial intelligence.

Abstract

Why did the emergence of our species require a timescale similar to the entire habitable period of our planet? Our late appearance has previously been interpreted by Carter (2008) as evidence that observers typically require a very long development time, implying that intelligent life is a rare occurrence. Here we present an alternative explanation, which simply asserts that many planets possess brief periods of habitability. We also propose that the rate-limiting step for the formation of observers is the enlargement of species from an initially microbial state. In this scenario the development of intelligent life is a slow but almost inevitable process, greatly enhancing the prospects of future SETI experiments such as the Breakthrough Listen project.