For years people wondered why earth's paleo-climate has warm spikes every hundred thousand years or so and other long range fluctuations, Mars may be part of the answer. Earth and Mars orbits have some slight entanglement which every so often resonates, transferring some angular momentum from one planet to the other, making a small disturbance of the axis and orbit vis a vis the sun. This is a bit preliminary but there's a signature in alternating layers of limestone and shale laid down some 87 million years ago in what's now Colorado and that's where it points. Beautiful!!
HotAir.com where I first read about it.
More perspective from an article at iflscience.com: