Justin Hickey reviews David Toomey's book in Open Letters Monthly:
And that is what Toomey means when he suggests searching for “life that is very, very different from our own.” He refers to life that doesn’t use water as a cellular medium, or is built from a different set of amino acids. Ultimately, he searches for life that does not share the ancestry common to everything else living on Earth, including frogs, strawberries, that orange mold in the shower, and you. Toomey, in his conversational prose, puts it this way:
The physical boundaries within which life is possible are unknown and undefined, but most biologists believe that they must exist, for the simple reason that there are temperatures and pressures under which the structures of organisms–cells, DNA, and proteins–will break down, no matter how well protected. In short, life must have ultimate limits.
My fist non-fiction encounter with such limits came from archeologist Charles Pellegrino’s epic and consilient book Ghosts of Vesuvius. In the opening chapter, he dives into a tangent about Jupiter’s moons Ganymede and Europa, and the fact that they’ve got volcanic zones and underground oceans that experience tides: “With so many throws of the hydrothermal dice, the probability of extraterrestrial life in our solar system (including, just maybe, complex creatures resembling fish and crabs and not just bacterial mats) rises so high as to approach a biochemical and statistical certainty.”
More here.