Jupiter vs Earth Habitability

I searched, but didn't immediately find a related thread on this subject.

http://phys.org/news/2014-04-mighty-jupiter-earth-habitability.html

Quote :

Is Jupiter a friendly planet, Earth's enemy, or perhaps both? For decades, scientists have talked about how the giant gas planet keeps some asteroids from striking our small world, while others have pointed out that Jupiter's gravity could send some civilization-shattering asteroids our way.

While that debate goes on, a subtler question arises about how influential Jupiter was in the early Solar System. Jupiter is by far the heavyweight planet in the Solar System, weighing in at 320 Earth masses. Its gravity not only influences small asteroids that go by, but also tugs on other planets in the solar system – including our own.

What if Jupiter had had a more eccentric orbit? Could that have affected the habitability of Earth? A new peer-reviewed study published on preprint site Arxiv, called "The role of Jupiter in driving Earth's orbital evolution," examines these questions in more detail. It was presented at the Australian Space Science Conference.

Here's the paper it links to: http://arxiv.org/abs/1401.6741