Is life immortal? Far from it (far from equilibrium to be sure). Multicellular individuals (plants and animals) die. (Bacterla not necessarlly, barrlng accidents.) Whole species become extinct (99% of them have done so.)

Life on Earth has made it through 6 great extinctions already. But the death of the Sun and its expansion into a Red Giant will kill it, if not some earlier accident like an asteroid collision. ‘

Life is vulnerable, though quite robust and tough. In any case, in the eternal order, there is always a “life line” for Life.

“UP-ROOTING THE TREE OF LIFE.”:

Why did we ever think that there was a common ancestor of all living things on Earth? Why did we entertain even such exaggerated myths that there was a single original cell? We told stories such as the following: we shed millions of dead skin cells every day, each of which is a straight-line descendant of the first cell that ever lived. This claim has been proved to be absurd by a recent article by W. Ford Doolittle in Scientific American, February 2000, pp. 90-95.

We knew that bacteria freely swap genes, rather than following the strictly vertical-descent lines of sexual reproduction. But it took detailed DNA-comparison studies to show definitely that in the bacterial superkingdom there are complex genetic networks, not vertical trees of genetic descent. Species are ill-defined in this realm. The interacting units form a community rather than a species. Kinship links are horizontal as well as vertical, with diagonal crosslinks as well. -That is the substructure, the bottom “mush”, under the proper Eukaryotic “trees of life”. Sex was a belated invention of the Protists and Fungi, carrying on then to Plants and Animals. The tree is supported by a crosslinked net of roots.

Lateral gene transfer is like lateral thinking. Why did living forms give it up for mere sex? It could have been even more productive of novelty.