Breathing with the Earth
263
The pole shift happens so slowly that living things may well adapt to
it easily; the 50-percent decline in field strength also seems rather unim-
portant. However, since we know the micropulsations control biocycles,
including the timing of the mitotic rhythm, a major change in their
frequency could be catastrophic. Experiments with artificial extremely
low frequency fields (see Chapter 15) have shown that vibrational rates
near normal but slightly above, from about 30 to 100 hertz, cause dra-
matic changes in the cell cycle time. This interferes with normal growth
of the embryo and may tend to foster abnormal, malignant growth as
well. If a geomagnetic reversal raises the micropulsation frequencies into
this range, the accumulation of growth errors over many generations
could well mean extinction.
We have no way of making a forecast, however. Reversals seem to
happen at widely varied intervals, as often as every fifty thousand years
during some periods, many millions of years apart during other times.
The last one seems to have occurred about seven hundred thirty thou-
sand years ago. Several scientists have interpreted data from NASA's
MAGSAT orbiter, and from measurements of magnetic particles in lake
sediments, as indicating that the earth's magnetic field strength is
steadily declining, and has been for the last few thousand years. If so, we
may already be entering the next reversal, but it's also possible we're
merely experiencing one of the field's many short-term variations.
Nor can we be sure how serious a reversal would be for us. Hominids
have weathered them in the past, but we have an extra reason for being
uneasy this time. If we're entering a reversal now, it will be the first one
in which the normal field is contaminated with our own electromagnetic
effluvia, and the most powerful of these, at 50 and 60 hertz, fall right in
the middle of the "danger band" in which interference with growth
controls can be expected.
The field giveth as well as taketh away, however. If we can hang on
until the next peak of its strength, we may benefit from a subtle infusion
of electromagnetic wisdom. An ingenious theory recently proposed by
Francis Ivanhoe, a pharmacologist and anthropologist at two universities
in San Francisco, suggests how important it may have been to our own
development.
Ivanhoe made a statistical survey of the braincase volume of all known
Paleolithic human skulls, and correlated the increase with the magnetic
field strength and major advances in human culture during the same
period. Ivanhoe found bursts of brain-size evolution at about 380,000 to
340,000 years ago, and again at 55,000 to 30,000 years ago. Both
periods corresponded to major ice ages, the Mindel and Wurm, respec-