The division of a circle into 360 degrees is very ancient and goes back to the era of the ancient maps. The significance of 360 is that its prime factorisation is 2 x 2 x 2 x 3 x 3 x 5, thus making it evenly divisible by every single digit number except 7, and also by 10, 12, 15, 18 and 20. The ability of ancient man to appreciate this is evidence of high intelligence, and weighs against the notion of a slow upward evolution. There is circumstantial evidence that the calendar year once contained 360 days. To change this to the current approx. 365.25 days would require around a 1% change in the Earth’s distance from the Sun, or a speeding up of Earth’s rotation by around 1,4%. I think the latter is more likely as it could have been accomplished by a redistribution of mass during a global cataclysm, this would affect the planet’s angular momentum and so the movement of mass would require a compensating adjustment to rotation speed.