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.
The development of human characteristics took place over millions of years. The earliest primate (an order of mammals that includes humans, apes, and monkeys), no bigger than a rat, appeared 60 million years ago. About 10 million years ago, the Ramapithecus showed remarkable hominoid attributes. But there is no further evidence until 6 million years later. The first generally accepted hominoid is called Australopithecus, and some believe they are actually the most primitive of the human lineage. Homo habilis, dating back at least 2 million years in modern-day Africa, is undisputedly human.