A solar-powered airplane finished crossing the United States on Saturday, landing in New York City after flying over the Statue of Liberty during its historic bid to circle the globe, the project team said. The spindly, single-seat experimental aircraft, dubbed Solar Impulse 2, arrived at New York's John F. Kennedy International Airport at about 4 a.m. local time after it took off about five hours beforehand at Lehigh Valley International Airport in Pennsylvania, the team reported on the airplane's website. Such a pleasure to land in New York! For the 14th time we celebrate sustainability," said the project's co-founder Andre Borschberg on Twitter after flying over the city and the Statue of Liberty during the 14th leg of the trip around the globe. The Swiss team flying the aircraft in a campaign to build support for clean energy technologies hopes eventually to complete its circumnavigation in Abu Dhabi, where the journey began in March 2015. The solar cr...
In a rare congruence of new evidence, two fossil jaws described
Wednesday cast a fused beam of light on one of the darkest mysteries in
human evolution: the origin of our genus Homo. The two lower
jaws—one a reconstruction of a pivotal specimen found half a century
ago, the other freshly plucked from the badlands of Ethiopia—point to
East Africa as the birthplace of our evolutionary lineage.The new Ethiopian fossil, announced Wednesday online by the journal Science, pushes the arrival of Homo
on the East African landscape back almost half a million years, to 2.8
million years ago. The date is tantalizingly close to the last known
appearance, around three million years ago, of Australopithecus afarensis, an upright-walking, small-brained species best known from the skeleton called Lucy,
believed by many scientists to be the direct ancestor of our genus. The
new jaw, known as LD 350-1, was found in January 2013 just a dozen
miles from where Lucy was found in 1974.
"This is exciting stuff," says paleoanthropologist Donald Johanson, who discovered Lucy.
The Afar, part of the East African Rift Valley, has yielded
many other prize fossils of hominins—members of the extended human
family—including the previous earliest known Homo specimen, an upper jaw known as AL 666-1, dated to 2.3 million years ago. (Learn more about Ardi, another human ancestor from the Afar region.)
Fossils attributed to Homo in the period two to three million years ago are exceedingly rare. Bill Kimbel, director of the Institute of Human Origins at Arizona State University, in Tempe, who co-led the analysis of the new specimen, once said
that "You could put them all into a small shoe box and still have room
for a good pair of shoes." (See more about the hunt for fossils of humans' early ancestors.)
Among the features placing the new fossil in that singular
shoe box are slim molar teeth; a particular pattern of tooth cusps; and
the shape of the bony body of the mandible—all traits shared with later Homo. But the front of the jaw sports more primitive morphology, such as a receding chin line, characteristic of A. afarensis.
"This narrows the time period in which we can now focus our
search for the emergence of the human lineage," says Kimbel, who found
the AL 666-1 jaw in 1994. "It's very much a transitional form, as would
be expected at that age. The chin looks backwards in time. But the shape
of the teeth looks forward."
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