BOSTON, Aug. 1 (UPI) -- Life on Earth is premature, new research suggests. The theory contradicts the long-held belief that Earth and its life forms were late to the party.
The Earth is only 4.5 billion years old. The universe was born 13.8 billion years ago.
The basic fact of human existence suggests the universe is primed for life right now, but new analysis by scientists at the Harvard-Smithsonian Center for Astrophysics shows the chance for life to take hold improves greatly in the future universe.
Based on their understanding of the evolution of the early universe and the lifespan of stars, life first became possible 30 million years after the Big Bang and will cease to exist 10 trillion years from now. Scientists designed a model to understand when on the timeline between these two points will cosmic conditions be most conducive to life.
Their model highlighted the importance of star size. The first generations of stars were mostly too big, the research shows. Bigger stars burn brighter and faster, running out of fuel before life has time to evolve.
Smaller stars, which live longer, become more abundant over time. Stars with a mass 10 percent of the sun's burn for 10 trillion years, plenty of time for the planets that orbit them to yield life.
The new model -- soon to be published in the Journal of Cosmology and Astroparticle Physics -- suggests the chance of life will increase by a factor of 1,000 in the distant future.
"The chance of life grows much higher in the distant future," Harvard astronomer Avi Loeb said in a news release.
How did humans get so lucky? Scientists aren't entirely sure, but offer a couple of possibilities.
"One possibility is we're premature," Loeb said. "Another possibility is that the environment around a low-mass star is hazardous to life."
Many smaller stars like red dwarfs are volatile when they're young, emitting disruptive flashes of X-rays and other radiation bursts that could strip a young planet of its newly acquired atmosphere and limit the chances of life.
Loeb and his colleagues say astronomers need to study red dwarfs and other low-mass stars for rates of habitability among their orbital worlds.