Benner and colleagues suggest the reverse might be true. They point to an element called molybdenum, an oxidized version of which may have been crucial for life to evolve.
The problem is 3 billion years ago, Earth didn't have enough oxygen for molybdenum to form into the highly oxidized mineral believed to be necessary for life. But it could have on Mars, Benner said.
Later, life-bearing Mars meteorites could have crashed into Earth, seeding life here.
The molybdenum issue is part of a larger, more complicated puzzle about how the chemistry for life assembled and evolved.
Another factor in Mars' favor is that the planet had ample dry lands where life's chemistry could cook, while early Earth may have been too wet.
"The entire story keeps being added to," Benner wrote in an email to Discovery News, calling his new research "nothing revolutionarily new, just evolutionarily new."
Benner presented his findings at the annual Goldschmidt conference in Florence, Italy, on Wednesday.