|
|
Vaccines prevent between 2.5 and 4 million deaths every year.
A cataract is a clouding of the eyes' natural lens. As we age, some clouding of the lens may occur. The first sign of a cataract is usually blurry vision. Although glasses and other visual aids may at first help a person with cataracts, surgery may become inevitable. Cataract surgery is very successful in restoring vision, and it is the most frequently performed surgery in the United States.
The first documented use of surgical anesthesia in the United States was in Connecticut in 1844.
There are more nerve cells in one human brain than there are stars in the Milky Way.
It is believed that humans initially contracted crabs from gorillas about 3 million years ago from either sleeping in gorilla nests or eating the apes.