And on a larger excursion with friends to central Africa, which ended at some beach cottages on an island off Zanzibar, among their companions was anthropologist Donald Johanson, known for his work on the human ancestor Lucy, who helped teach them about human evolution.

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Recently, researchers found the missing link: the immediate ancestor of the Human Immunodeficiency Virus.

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New fossil evidence seems to confirm that a key ancestor of ours could walk upright consistently - one of the major advances in human evolution.

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The common ancestor is, however, too recent for the new species to be a remnant of the first human excursion from Africa, the one that led to Java man and Peking man, now known as Homo erectus.

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