I am not an expert and may be off-base here. But I believe that Chinese and Semitic writing systems are right-to-left (in the Chinese case, up-to-down first) and that these cultures used predominantly lunar calendars. Meanwhile, Western and Mayan writing systems are left-to-right, and these cultures used predominantly solar calendars. The moon waxes from right to left. Is it possible that calendar systems influenced writing direction?
