All Y chromosomes in existence today are descended from a single ancestor's who is thought to have lived about 140,000 years ago.

Doctors hope that one day the body's master cells, called stem cells, can be directed to grow in organs or tissues appropriate for transplant, use them to test drugs and potentially toxic chemicals, and may study them to gain insight into basic human biology.

Navigators have known for thousands of years that the ocean has variable currents, but it is only in the last half century that a reasonably clear picture has emerged of the patterns and causes of ocean currents.

Mary Wollstonecraft's A Vindication of the Rights of Woman (1792) was unprecedented in its first hand accounts of the indignities suffered by women and because it was eloquent and passionate in exposing and criticizing these indignities.

The current economic downturn has significantly reduced advertising income both for business journals as well as general consumer magazines, especially if focusing on technology.

Medicare, the United States government's health insurance program for the elderly and disabled, covers the full cost of home health care, but not with other non hospital services where 20 percent of the costs must be paid by beneficiaries.

Over the course of the eighteenth century, the average output of ironwork tripled as a result of several improvements in blowing machinery and because coal replaced charcoal as the fuel used in the smelting of iron ore.

Because fish look through water, their eyes are very different from a mammal.

Whereas lines of competition are clearly defined in the more established industries, in the Internet industry they are blurred and indistinct, as companies that compete one day may be partners the next.

The first English settlers to establish a permanent colony in America did it not at Plymouth but along the shore of the James River west of Chesapeake Bay.