'द प्रोपेगेशन ऑफ इनोवेशन वेव्स' और स्थानिक विसरण सिद्धांतों का प्रतिपादन किसके द्वारा किया गया था?

In traditional anthropological classification of human races, which racial group was characterized as 'yellow-skinned'?

What is the approximate estimated proportion of ecumene (habitable) and non-ecumene (uninhabitable/sparsely inhabited) areas on the Earth's surface?