What is the concept of genetic drift?

Which is the main inference that can be drawn from adam smith's book the wealth of nations? a) for an economy to work flawlessly, it shouldn't have to serve and moral goals.b) the government must control a free-market economy, or economic problems will arise.c) a free-market economy works well only without the government's interference. d) free trade will only hurt economies and should be stopped by governments.

Why did trade along the silk road increase after it fell under mongol control? o people stopped using camels the mongols paved the road o it became safer to travel the mongols were better traders next question ask for

Why do many scientists suppose the land bridge theory of migration?