One reason for thinking that life on Mars might be similar to life on Earth is if they both had a common origin. This would be made possible by their relativel

One reason for thinking that life on Mars might be similar to life on Earth is if they both had a common origin. This would be made possible by their relatively close proximity. Bacteria could have been transported between planets by traveling on meteorites. See also: https://en.wikipedia.org/wiki/Martian_meteorite https://en.wikipedia.org/wiki/Martian_meteorite https://en.wikipedia.org/wiki/Panspermia https://en.wikipedia.org/wiki/Panspermia