The World of REM Sleep
One Side of Alice's Looking Glass
Some half billion years ago when the earth spun on its axis somewhat faster than today, days and nights were shorter, and the first metazoans (creatures with more than one cell) were roaming the ancient seas. At that time as well, the moon swung in a considerably closer orbit to the earth, casting a more dramatic light over the darkened seascape. Unfortunately, there were no eyes to behold the sight and thus no witnesses to the awesome oversized nighttime lunar apparition. Yet it now appears that there were indeed blind witnesses whose descendants still dwell in the depths. One of the earth's most ancient sea creatures is the chambered nautilus, a fellow who manufactures a new chamber in his shell as he outgrows the old one. This new chamber has been thought to be a recorder of the moon's changing orbit, for the chamber seems to be manufactured on a lunar month schedule. As the lunar orbit has enlarged over the last 500 million years, the lunar month has lengthened, and so the growing cycle for each chamber in the nautilus has lengthened. By calculating the rate of change of the lunar orbit and by sampling the ancient shells from each epoch, we have perhaps discovered nature's "moon dial," one of the oldest of biological clocks. This is but one of many time intervals that appear synchronized with one another in all life systems on our planet.