The Earth's pulse does not actually beat every 27.5 million years. Scientists have not discovered any regular periodicities in the Earth's geological or biological processes with a 27.5-million-year cycle. This belief is based on a misinterpretation of the Milankovitch cycles.

The Milankovitch cycles refer to the variations in Earth's orbit and the tilt of its axis over long periods of time. There are 3 main Milankovitch cycles:

1. Eccentricity: The variation in Earth's orbit from nearly circular to slightly elliptical. This cycle has a period of about 100,000 years.

2. Obliquity: The variation in the tilt of Earth's axis of rotation from about 22.1 to 24.5 degrees. This cycle has a period of about 41,000 years.

3. Precession: The "wobbling" of the Earth's axis of rotation. This cycle has a period of about 26,000 years.

Combinations of these cycles affect the amount of solar energy that reaches different parts of Earth's surface, which in turn influence climate patterns and the timing of ice ages. But they do not have a periodicity of exactly 27.5 million years.