Why does ethnic diversity lead to violent conflicts in some places but not in others?

Can someone read this article and tell me the 1) key ideas and 2) one key quote (copy and paste the link the article is not to long at all)from

When comparing the northern and southern hemisphere, why are the peak maximum and minimum values of insolation at different times of the year? specifically, why is the peak max of incoming solar radiation in june for the northern hemisphere, but in december for the southern hemisphere? pick the best, most complete answer. because of variations in the incident angle of solar radiation, due to the tilt of earth's axis, the northern hemisphere receives more direct solar radiation in june while the southern hemisphere receives less direct solar radiation. the reverse is true in december. because of earth's tilt, as the earth progresses in its revolution around the sun, the northern hemisphere is relatively closer to the sun in june while the southern hemisphere is relatively farther from the sun. the reverse is true in december. because of earth's elliptical orbit, the northern hemisphere is relatively closer to the sun in june/july while the southern hemisphere is relatively farther from the sun. the reverse is true in december. because of variations in the incident angle of solar radiation and the length of day, due to the tilt of earth's axis, the northern hemisphere receives more direct solar radiation and has longer daylight hours in june while the southern hemisphere receives less direct solar radiation and shorter daylight hours. the reverse is true in december.

The symbols found on the map below indicate where fossils have been found in the same layer of sediment. each unique symbol represents fossil locations of a particular species.