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By Root 1250 0

extracellularly, they use up water and leave pockets of fluid of higher concentration. These pockets then act to osmotically withdraw water from the inside of the cell. In effect, gradual freezing results in the extracellular ice formations with a concomitant dehydration of the cell contents, so that no ice crystals are formed within the cell—ice crystals that would otherwise tear the cell organelles. Or, if ice crystals do form inside the cell, they are small and less damaging. Alternatively, the water may solidify into glass form—a type of liquid that is hard and in which the remaining water molecules are unavailable to form ice crystals perhaps because they closely adhere to the molecules of the cell structure. In contrast, during rapid freezing there is not sufficient time for the osmotic exchange of water (between intra-and extracellular) compartments, and so without prior dehydration the cell contents freeze, resulting in large, jagged ice crystals that shear and tear the cell organelles and membranes.

Let us return now to why northern Eurosta populations avoid supercooling by having a protein in the blood that promotes ice formation. They must thus have freezing-tolerance. Southern populations lack the protein that prevents supercooling and they can and most likely do supercool. Not having been selected for freezing-tolerance, they’ve perfected instead the mechanisms to prevent freezing rather than those that would help them survive it. The combination of antifreeze and supercooling is reliably sufficient to preclude ice formation in their environment. Rate of ice formation is no longer an issue when ice formation is unlikely, so no precautions for ensuring slow freezing (to promote cell dehydration freezing survival) are necessary.

A convincing demonstration that dehydration secondarily confers freezing tolerance can be found in the larvae of the African desert fly (Polypedilum vanderplanki), which periodically dry up in the temporary desert pools within which they live. The larvae are adapted to survive losing 92 percent of their body water, and such desiccated larvae are essentially immortal and can survive immersion in liquid helium (to -269°C), within 4°C or potentially at absolute zero, or 0°K, the lowest temperature in the universe. When rehydrated by dropping them into water they become “instant insects.” They then again have narrow temperature tolerances, surviving only from 10° to 42°C. Are they alive before they are wetted? I think not. What they are is potentially alive, and I base that supposition on some oblique illumination from recent research in geology and microbiology.

About 250 million years ago—that’s about 190 million years before the dinosaurs went extinct—there was an inland sea in North America. The ocean eventually evaporated where there is now the New Mexico desert. It left salt deposits a half mile below the now sunbaked ground. Tiny pockets of ancient seawater became trapped in these salt deposits and from them microbiologists have reported isolating, and then growing (actively metabolizing and reproducing), novel Bacillus-like bacteria. Additionally, they found other microbes whose DNA does not match DNA of known organisms, so that these novel forms are thought to be the first, or among the first, ancient microorganisms that inhabited the planet. Bacteria had previously been isolated from guts of dead insects entrapped in amber for 125 million years, and the microbiologists reported that these bacteria could also be grown in culture, making it possible that living 125-million-year-old organisms had been found.

Polyphemus moth pupae from the field in winter have three-way protection:

• tough shells (cocoons) that are impenetrable by most birds

• a camouflage wrapping of dead leaves

• biochemical protection to prevent death by freezing

So fantastic are these results that they should be and are viewed with skepticism in the scientific community. However, I think they are fantastic, not because of magical processes new to science that we don’t yet understand, but because of