It is observed that the human population keep increasing significantly and it began to increase noticeably around 10,000 years ago.The greatest factor of this increase is the rapid development of the agricultures in lands, as well as the domestication of animals. These are the reasons why population increases at that time.
Answer:
The return of blood to the heart is assisted by the action of the skeletal- muscle pump. As muscles move, they squeeze the veins running through them. Veins contain a series of one-way valves, and they are squeezed, blood is pushed through the valves, which then close to prevent backflow.
Wind shear can result in the formation of a tornado
