जनांकिकीय संक्रमण सिद्धांत (Demographic Transition Theory) के अनुसार, वह कौन सी अवस्था है जिसमें जन्म दर उच्च बनी रहती है लेकिन मृत्यु दर में तेजी से गिरावट आती है?

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?