Mass extinctions over the past 550 million years are explained just as well by a uniform random distribution as by any galactic mechanism — no clear link between the Sun's galactic orbit and Earth's extinction record; meanwhile the Sun's motion through the Galaxy does not significantly influence the impact-cratering rate, and Earth's own obliquity (tilt) is the dominant trigger of ice-age deglaciations over the past 2 million years.

— In our words · Source: Investigations into the impact of astronomical phenomena on the terrestrial biosphere and climate (Fabo Feng)