Heart disease kills about a half-million people every year in the United States. It begins with the clogging of the arteries - which is called atherosclerosis. When there is too much saturated fat and trans fat in the bloodstream, it sticks to the walls, which narrows the passageway that blood must travel through.
The earliest known fossil of a human ancestor, a female Ardipithecus ramidus specimen nicknamed Ardi, is 3.2 million years old. Scientific evidence says that the first modern humans, Homo sapiens, appeared more than 200,000 years ago. Some fossils from the middle Pleistocene period (about 400,000 years ago), referred to as Homo sapiens rhodesiensis, may be archaic Homo sapiens - a transitional species.
Thursday 24 March 2011 14.01 EDT First published on Thursday 24 March 2011 14.01 EDT. Humans first arrived in North America more than 2,500 years earlier than previously thought, according to an analysis of ancient stone tools found in Texas. And the people who left them appear to have developed a portable toolkit used for killing and preparing meat.