alt Hacker NewsThe paper claims LUCA doesn't count as life because it still depended on its environment to metabolize.
It's kind of interesting that there's parasites that arguably don't meet this definition either. Looking it up: Chlamydia can't reproduce independently; relies on its host's metabolism. Microsporidia can't make ATP on its own. Are these "life"?
The difference is more on survival. A closed loop metabolism is indeed a good boundary marker. Viruses would fail this. But many have “closed but for a few critical dependencies”, and the argument here is that when life depended on metals like this, it’s more critical dependencies than closed loop.
Somewhere in there is a transition. But it’s poorly defined, and so the argument can be there was a bifurcation of sorts.