<p>A fossil lower jaw found in Ethiopia has pushed back evidence for the earliest human genus -- Homo -- to 2.8 million years ago, around 400,000 years earlier than previously thought.<br /><br /></p>.<p>The new fossil unearthed at Ledi-Geraru research area in Ethiopia provides clues to changes in the jaw and teeth in Homo only 200,000 years after the last known occurrence of Australopithecus afarensis ("Lucy").<br /><br />Found by team member and Arizona State University (ASU) graduate student Chalachew Seyoum, the Ledi-Geraru fossil preserves the left side of the lower jaw, or mandible, along with five teeth.<br /><br />The fossil analysis revealed advanced features, for example, slim molars, symmetrical premolars and an evenly proportioned jaw, that distinguish early species on the Homo lineage.<br /><br />"In spite of a lot of searching, fossils on the Homo lineage older than 2 million years ago are very rare," said Brian A. Villmoare of the University of Nevada, Las Vegas.<br />"To have a glimpse of the very earliest phase of our lineage's evolution is particularly exciting," Villmoare said.<br /><br />"The Ledi jaw helps narrow the evolutionary gap between Australopithecus and early Homo," said William H. Kimbel, director of ASU's Institute of Human Origins.<br />"It's an excellent case of a transitional fossil in a critical time period in human evolution," Kimbel said.<br /><br />Climate change that led to increased African aridity about 2.8 million years ago is often thought to have stimulated species appearances and extinctions, including the origin of Homo.<br /><br />The findings appeared in the journal Science.</p>
<p>A fossil lower jaw found in Ethiopia has pushed back evidence for the earliest human genus -- Homo -- to 2.8 million years ago, around 400,000 years earlier than previously thought.<br /><br /></p>.<p>The new fossil unearthed at Ledi-Geraru research area in Ethiopia provides clues to changes in the jaw and teeth in Homo only 200,000 years after the last known occurrence of Australopithecus afarensis ("Lucy").<br /><br />Found by team member and Arizona State University (ASU) graduate student Chalachew Seyoum, the Ledi-Geraru fossil preserves the left side of the lower jaw, or mandible, along with five teeth.<br /><br />The fossil analysis revealed advanced features, for example, slim molars, symmetrical premolars and an evenly proportioned jaw, that distinguish early species on the Homo lineage.<br /><br />"In spite of a lot of searching, fossils on the Homo lineage older than 2 million years ago are very rare," said Brian A. Villmoare of the University of Nevada, Las Vegas.<br />"To have a glimpse of the very earliest phase of our lineage's evolution is particularly exciting," Villmoare said.<br /><br />"The Ledi jaw helps narrow the evolutionary gap between Australopithecus and early Homo," said William H. Kimbel, director of ASU's Institute of Human Origins.<br />"It's an excellent case of a transitional fossil in a critical time period in human evolution," Kimbel said.<br /><br />Climate change that led to increased African aridity about 2.8 million years ago is often thought to have stimulated species appearances and extinctions, including the origin of Homo.<br /><br />The findings appeared in the journal Science.</p>