New York: Lucy– the common name accorded to the world-famous fossilized remains of an early human ancestor who lived 3.18 million years ago — was adept at walking on her two legs as well as climbing trees, researchers have determined. Evidence preserved in the internal skeletal structure of Lucy, a member of the ancient human species known as Australopithecus aphaeresis, suggests that she climbed trees, the study said.
Since Lucy’s discovery in Ethiopia 42 years ago, paleontologists have debated whether she spent her life walking on the ground or combined walking with frequent tree climbing. The new analysis, published in the journal PLOS ONE, showed that Lucy’s upper limbs were heavily built, similar to tree-climbing chimpanzees, supporting the idea that she often used her arms to pull herself up, most likely onto tree branches.
“It may seem unique from our perspective that early hominines like Lucy combined walking on the ground on two legs with a significant amount of tree climbing, but Lucy did not know she was unique,” said one of the researchers John Kappelman from The University of Texas at Austin in the US. Researchers also suggested that because her foot was better adapted for bipedal locomotion — or upright walking — rather than grasping, Lucy had to rely on upper-body strength when climbing, which resulted in more heavily built upper-limb bones.
“We were able to undertake this study thanks to the relative completeness of Lucy’s skeleton,” study’s lead author Christopher Ruff, Professor at Johns Hopkins University School of Medicine, noted. “Our analysis required well-preserved upper and lower limb bones from the same individual, something very rare in the fossil record,” Ruff said. A recent study by Kappelman proposed that Lucy probably died after falling from a tall tree, where she may have been nesting to avoid predators.
NASA’s Voyager 2 becomes second spacecraft to reach interstellar space
Washington: Nasa’s Voyager 2 has become only the second human-made object to reach the space between stars.
Nasa said that the spacecraft left the region of the sun’s influence last month and is now beyond the outer boundary of the heliosphere, about 11 billion miles from Earth. It is trailing Voyager 1, which reached interstellar space – the vast, mostly empty area between star systems – in 2012.
The study, published in the journal Nature Astronomy, confirmed Voyager 2’s passage on November 5, 2018, into the ISM by noting a definitive jump in plasma density detected by a plasma wave instrument on the spacecraft.
The marked increase in plasma density is evidence of Voyager 2 journeying from the hot, lower-density plasma characteristic of the solar wind to the cool, higher-density plasma of interstellar space, the researchers said.
It is also similar to the plasma density jump experienced by Voyager 1 when it crossed into interstellar space, they said.
“In a historical sense, the old idea that the solar wind will just be gradually whittled away as you go further into interstellar space is simply not true,” said Professor Don Gurnett from the University of Iowa, and corresponding author on the study.
Data from the instrument on Voyager 2 also gives additional clues to the thickness of the heliosheath, the outer region of the heliosphere and the point where the solar wind piles up against the approaching wind in interstellar space, which Gurnett likens to the effect of a snowplow on a city street.