RIO DE JANEIRO (Reuters) -- Anthropologists in Rio unveiled the oldest
                  known human fossil from the Americas Monday, a woman's skull with
                  African features that could revolutionize theories on the continent's early
                  inhabitants.

                  The fossil -- first discovered in Brazil in 1975 but only recently found to
                  come from a woman who lived 11,500 years ago -- shows there were
                  human beings on the continent long before Asian immigration, said
                  anthropologist Ricardo Ventura Santos.

                  "This is a piece that in practice is important toward understanding ... the
                  settlement of the Americas," said Ventura Santos, of the National Museum
                  and the prestigious Federal University of Rio de Janeiro (UFRJ).

                  "There's a lot of curiosity about it, that's why we're showing it to the media
                  today."

                  Scientists dubbed the woman "Luiza," Brazil's answer to the famed "Lucy,"
                  just over a year ago when new methods proved she was the earliest known
                  American. Luiza's namesake is a 3.2 million-year-old human ancestor found
                  in Ethiopia and now on display in a Paris museum.

                  Scientists say Luiza was a nomad who wandered with about a dozen
                  relatives in an area of what is now central Brazil, eating the natural vegetation
                  or on occasion animal meat. She died at around age 20 in some sort of
                  accident.

                  Before Luiza's appearance, paleontologists had been working on the theory
                  that the earliest Americans were the Asian ancestors of the Indians that
                  European colonizers encountered when they arrived on the American
                  continents 500 years ago.

                  These ancestors would have come from what we now know as Siberia and
                  Mongolia and crossed the Bering Straight between Asia and North America
                  on a glacial bridge at the end of the last Ice Age.

                  About a year ago, archeologist Walter Neves, one of the few specialists in
                  human paleontology in Brazil, took an interest in the unusual shape of Luiza's
                  skull, which had been packed away for decades in the museum's vast
                  archives.

                  He believed the skull, which had been originally dug up from a 43-foot deep
                  cavern in the Brazilian state of Minas Gerais, showed Negroid features
                  rather than the Mongoloid features typical of Brazil's Indians.

                  "Its characteristics are very different in relation to the native population.
                  Therefore, it has an very big importance, above all in explaining the
                  settlement of the Americas and also for the history of humanity," said Jose
                  Henrique Vilhena, UFRJ's rector.

                  A tomography commissioned by a documentary team from Britain's BBC
                  and Rio's National Museum confirmed that Luiza had the round eyes, large
                  nose and pronounced chin characteristic of Australian aboriginals and native
                  Africans.

                  A team of specialists in England did the imaging of Luiza's skull and molded
                  a bust of her head that will be on display alongside her skull at the museum.

                  The scientists believe Luiza's ancestors were in the same line of descent as
                  Australia's aboriginals and crossed the northernmost Pacific Ocean by boat
                  nearly 15,000 years ago, next to glaciers that were forming at that time.

                     Copyright 1999 Reuters.