Conclusions:

The precessional cycle is related to the moon's orbit of the earth. Billions of years ago when the earth and moon were forming, the regular motion of the moon around the earth stabilized the rotation of the earth on its axis. The moon's orbiting of the earth contributes to the pointing of the earth's axis to north. The Major Glaciations of the earth in recent times seem to have a direct correspondence to the 26,000-year cycle related to the precession of the equinox. The wobble of the earth on its axis makes different parts of the earth face the sun during different ages, thereby causing certain areas to melt the ice. The glaciated landmasses become thicker and the sea level would lower when ice ages occur. The fact that several of these great ice ages started at regular intervals indicates that we may be due for the start of another ice age sometime in the next thousand years or so. In that case, thank God and global warming, which may stave off the cold.

It's 80,000 years until the peak of next major ice age according to Hoffman and Schrag in the article "Snowball Earth" Scientific American January 2000.

Notes on the human timeline:

Human ancestors split from apes 18-30 million years ago. True humans are thought to have been around for at least 1 million years now. Hominoids such asustralopithecines lived from 1 to 2 million years ago in the Early Pleistocene era. Neanderthal Man peaked in Europe about 120,000 years ago but were replaced by Homo Sapiens 70k ago. Written history may have began as early as 5,200 years ago or about 3,200 BC although this date keeps getting pushed back as more archeological evidence is found. Early markings on bone may represent lunar calendars that are much earlier and astronomical too.