In other words, they're saying "we don't know yet", which most of us kinda already knew.
...they argue that the life here on Earth could be common, or it could be extremely rare...
STARGAZING: All I see are the lights of a billion places I'll never go. --Howard Tayler, Schlock Mercenary
"It is not the strongest of the species that survive, nor the most intelligent, but the one most responsive to change." Charles Darwin
"It is the duty of the writers to seduce me into suspending my disbelief!" Paul Beardsley