Lascaux cave walls show groups of dots and squares depicting moon's 29-day cycle. Row of 13 dots ends in square below deer painting. Another row of 29 dots under horse marks full lunar phases. Patterns represent new moon disappearance. Cro-Magnon tracked critical natural rhythms for survival. Constellations like Pleiades appear above bull's shoulder. Shaft off main chamber shows more star patterns. Paintings created during European ice age in temperate Dordogne valley.