An interesting article on physicsweb:
Planetary scientists have developed a theory that can explain three outstanding puzzles about our solar system: Why do the giant planets have eccentric and tilted orbits? How did Jupiter get its Trojan asteroids? And what caused the Late Heavy Bombardment some 700 million years after the Earth and Moon were formed? The answer seems to be that all three phenomena seem to be a direct result of Saturn and Jupiter shifting their orbits in the early solar system.