Mass extinctions and huge geological shifts are the result of dark matter, a US scientist has said.
Michael Rampino, a biology professor at the New York University, claims Earth's path around and through the Galactic disk could have a direct effect on geological and biological changes on our planet.
Published in the Monthly Notices of the Royal Astronomical Society, Rampino says movement through our galaxy's disk – where dark matter is concentrated – could explain regular periods of geological upheaval and mass extinction events, such as the asteroid impact that killed off the dinosaurs.
Previous studies have shown the Earth rotates around the Galactic disk once every 250 million years. However, it travels on a wavy path, dipping through the disk every 30 million years.
The disk is crowded with stars and clouds of dust and gas. It also has a high concentration of dark matter – elusive subatomic particles that make up about 27% of the universe.
By analysing the pattern of the Earth's passes through the disk, Rampino found the timings appear to correlate with periods of comet impacts and mass extinction events on Earth.
He believes that the dark matter in these areas of the galaxy disturbs the pathways of comets that would normally be orbiting far from Earth – instead, the dark matter makes them take unusual paths, causing them to collide with our planet.
Furthermore, each dip can lead dark matter to accumulate within Earth's core – when the particles eventually annihilate one another they produce considerable heat, which could trigger volcanic eruptions, magnetic field reversals and changes to sea level. These geological events also appear to peak every 30 million years, Rampino notes.
He wrote: "Passage of the Earth through especially dense clumps of dark matter, composed of Weakly Interacting Massive Particles in the Galactic plane, could also lead to heating in the core of the planet through capture and subsequent annihilation of dark matter particles.
"This new source of periodic heating in the Earth's interior might explain a similar 30 million year periodicity observed in terrestrial geologic activity, which may also be involved in extinctions. These results suggest that cycles of geological and biological evolution on the Earth may be partly controlled by the rhythms of Galactic dynamics."
Rampino said his findings could have a wide impact on how we understand the geological and biological development of Earth.
"We are fortunate enough to live on a planet that is ideal for the development of complex life," he said. "But the history of the Earth is punctuated by large scale extinction events, some of which we struggle to explain. It may be that dark matter - the nature of which is still unclear but which makes up around a quarter of the universe - holds the answer. As well as being important on the largest scales, dark matter may have a direct influence on life on Earth."