Complex sentence: Early evidence of such practices appears as markings on bones and cave walls, which show that lunar cycles were being noted as early as 25,000 years ago; the first step towards recording the Moon's influence upon tides and rivers, and towards organizing a communal calendar.
Split into simpler sentences: Early evidence of such practices appears as markings on bones and cave walls, which show that lunar cycles were being noted as early as 25,000 years ago. This was a first step towards recording the Moon's influence upon tides and rivers, and towards organizing a communal calendar.