Not yet, I agree, but who is to say they couldn't? Limiting life to cell based biology is a somewhat lousy definition by the only example we know. I prefer the

Not yet, I agree, but who is to say they couldn't? Limiting life to cell based biology is a somewhat lousy definition by the only example we know. I prefer the generalized definition in "What is Life?" by Erwin Schrödinger which currently draws the same line (at cellular biology) but could accommodate other forms of life too.