Detailed Instructions: In this task, you are given a text of many news articles seperated by special token "|||||". Your task is to summarize them.
Q: Scratch that: Marks on Homo habilis teeth suggest which hand the early human used to cut its meat. 
  
 Nearly 2 million years ago, an early human used a stone tool to carve hunks of meat held in its mouth, an activity that left behind wear marks in its teeth. 
  
 And the direction of the grooves suggest that this individual had a dominant right hand. 
  
 Right-handedness is significantly more common than left-handedness in modern humans, and the trait emerged early in the lineage's evolution, researchers have said. This discovery, which presents the oldest evidence of right-handedness, could prompt a deeper look into the fossil record, to determine when human ancestors first demonstrated right-handed dominance. [The 10 Biggest Mysteries of the First Humans] 
  
 The fossil, a mostly intact upper jaw, was found in an archaeological dig site in northern Tanzania, in a location with stone tools and large mammal bones nearby. The jaw belonged to Homo habilis, a human ancestor that lived 2.4 million to 1.4 million years ago and is the oldest known ancestor in the Homo lineage. 
  
 Homo habilis means "handy man," and though the newly discovered specimen's hands were nowhere to be found, its jaw and teeth provided researchers with unexpected evidence of whether it was a so-called "righty" or "lefty." 
  
 The teeth were very well-preserved, with enamel still covering most of their surfaces. Close inspection of two central incisors in the jaw revealed concentrations of scratch marks; in one tooth in particular, they were primarily angled to the right side of the body. 
  
 According to the scientists, these marks were created over time, as the "handy man" was cutting up his meat. He would have gripped a hunk of flesh in his mouth, steadied the meat by pulling on it with one of his hands and used the other hand — which was probably the dominant one — to saw pieces of meat with a stone tool, which would occasionally scrape against his teeth. 
  
 a. A right-handed Homo habilis would have pulled at the meat with the left hand and cut with the right. b. A stereomicroscopic composite of the cast of one of the teeth used in the analysis. Credit: David W. Frayer 
  
 The right-leaning direction of these scrapes — which have also been detected in fossil teeth belonging to Neanderthals and other human relatives — told the scientists that a tool held in the right hand had made the marks. 
  
 Humans aren't the only mammal species that favors one hand over the other; this trait appears in animals "from kangaroos to chimpanzees," the study authors wrote. However, having a dominant hand that appears overwhelmingly across an entire species is uniquely human; 90 percent of people today are right-handed, the researchers estimated, compared with 50 percent of individuals in humans' primate relatives. 
  
 But when did humans first develop a preference for using the right hand over the left? Fossil arm bones might hold clues, but researchers would need both arms from a single individual to tell which hand the individual used more often in life, and that's proven hard to find in the fossil record. 
  
 However, this new discovery suggests that scientists could find the evidence preserved in fossil teeth, which are more plentiful than matched pairs of arm bones, the researchers said. While this is as yet the only example of dominant hand use in humans' early lineage, other fossils may provide the clues researchers need to trace the origins of "righty" vs. "lefty," the scientists said. 
  
 The findings were published online in the November issue of the Journal of Evolution. 
  
 Original article on Live Science. ||||| Fossils from the “handy man” of the human family tree have now provided the oldest known evidence of right-handedness in our lineage. 
  
 The discovery comes from a 1.8-million-year-old upper jawbone of Homo habilis, a human ancestor who lived in eastern and southern Africa from 2.4 to 1.4 million years ago. Scientists suspect the species was a regular user of stone tools, which are found in abundance around the fossil discovery site. 
  
 The jawbone’s teeth, still firmly in place, are covered in diagonal scratches that were most likely made when this Homo habilis individual, perhaps a female, accidentally nicked her teeth with a stone tool held in her right hand. 
  
 While the Homo habilis jawbone is a sample size of one, its very existence says that scientists could use the species’ teeth to learn more about ancient humans’ brain organization. 
  
 Today, about 90 percent of humans are right-handed, a skewed ratio that’s associated with how much the two hemispheres of our brain divide up processing different tasks. Intriguingly, the human brain’s left hemisphere not only controls the body’s right side, but it also contains the centers that control language. 
  
 “There’s an association between right-handedness, cerebral lateral asymmetry, and language—all fit together in a package,” says anthropologist David Frayer of the University of Kansas. Frayer led the study of the Homo habilis jawbone, published online last week in the Journal of Human Evolution. 
  
 This relationship seems to hold across primates: Neanderthal remains, for instance, show that they were also overwhelmingly right-handed, while chimpanzees are about three-fifths right-handed, by some estimates. Bonobos show no preference for either hand. 
  
 Getting Into the Groove 
  
 The Homo habilis fossil is from Tanzania’s Olduvai Gorge, one of the richest fossil sites containing ancient hominin remains. The specimen is more than 1.3 million years older than the next oldest evidence for handedness in humans, a set of Homo heidelbergensis jawbones and teeth first described in 2009. 
  
 Counterintuitively, scientists often have to rely on ancient teeth to determine what ancient hominins were doing with their hands. 
  
 Experiments with modern humans wearing mouth guards suggest that if a person holds an object taut between her mouth and nondominant hand—a large hunk of food, perhaps, or maybe a hide—and then cuts it with a stone tool in her dominant hand, the tool occasionally nicks the person’s teeth. 
  
 If a person is right-handed, those grooves run from the upper left to the lower right of the tooth surface. 
  
 Sure enough, when Frayer and his colleagues examined the Homo habilis jawbone, the teeth exhibited these diagonal grooves, suggesting that 1.8 million years ago, someone in what’s now Tanzania may well have been a right-hand woman—or a right-hand man. 
  
 “Teeth are incredible because they preserve their chemistry, growth, and development,” says Debbie Guatelli-Steinberg, an anthropologist at the Ohio State University who wasn’t involved with the study. “You can extract a lot from them—no pun intended.” 
  
 Frayer and Guatelli-Steinberg both point out, however, that one set of teeth cannot tell the whole story. 
  
 “For this to really speak to the human trait—a predilection of right-handedness—we need to get some idea of the proportion of individuals who were using their right hands,” says Guatelli-Steinberg. 
  
 Frayer says that he hopes the new study will help to solve that problem by inspiring other researchers to examine additional Homo habilis teeth for the telltale grooves. ||||| As any lefty knows well, our world is largely built for righties. Basic items from scissors and knives to cameras and computer mice are all designed to suit the roughly nine in 10 people who are right-handed. 
  
 New evidence suggests this lopsided split may date back more than a millennia, according to an international team of anthropologists. 
  
 Researchers said a 1.8-million-year-old fossilized jaw bears the scratches of a person who was right-handed. This finding could help scientists better understand how the human brain developed and when we first developed language. 
  
 The Homo habilis fossil is more than four times older than what scientists previously believed was the oldest fossil evidence of our right-handed tendencies, according to the study published Oct. 20 in the Journal of Human Evolution. 
  
 Three perspectives of the 1.8-million-year-old fossil. Image: David frayer 
  
 The fossil discovery "may tell us something about when language first appeared," said David Frayer, the study's lead author and a professor of biological anthropology at the University of Kansas in Lawrence. 
  
 "Language, handedness, brain laterality — the difference in function between the left and right side of the brain — are all interrelated," Frayer told Mashable. 
  
 The study carries a big caveat. 
  
 Frayer and his colleagues were only able to study one Homo habilis fossil. Few other fossils from this age have been discovered, and they largely reside in collections in Africa, where nobody on the team works, he said. 
  
 If other scientists find evidence of a left-handed human ancestor from the same period, it would undermine this study's conclusions about when humans developed a common dominant hand. 
  
 "This specimen is only one, but we're hoping that people will find more, or look at more specimens," Frayer said. 
  
 Right v. Left 
  
 The prevalence of righties is a defining characteristic of our species. 
  
 Researchers estimate that about 90 percent of modern humans are right-handed. Neanderthals and pre-Neanderthals likely had a similar ratio of righties to lefties, according to fossil evidence dating back 430,000 years. 
  
 Left-handedness is less rare among U.S. presidents, it turns out. President Barack Obama followed seven 20th-century left-handed presidents, including Bill Clinton, George H.W. Bush and Ronald Reagan. Image: Ron Sachs-Pool/Getty images 
  
 Apes, by contrast, are closer to a 50-50 split when it comes to right- and left-handedness. 
  
 The new study supports earlier evidence that Homo habilis were closer to modern humans than apes and that they had brain lateralization, meaning their right and left halves of the brain specialized in different functions. 
  
 In humans, the left half of the brain controls the right side of the body. The left side also plays a primary role in speech production and language comprehension. That is partly why scientists believe that our right-handedness is associated with our brain functions and language capacity. 
  
 "Neanderthals at least probably had language," Frayer said. He added that the Homo habilis fossil "is just the beginning to look for that kind of evidence in the earliest Homo [habilis]." 
  
 Scratched teeth 
  
 The 1.8-million-year-old upper jaw fossil was discovered in present-day Tanzania. Frayer and his colleagues determined the bone belonged to a righty by studying the scratch marks across six front teeth. 
  
 Because the scratches appeared only on the front of the teeth — not the backs or sides — the anthropologists surmised the early human nicked his or her teeth during a pre-historic feast. 
  
 Frayer described an individual clenching a strip of tough meat between her teeth. Her left hand pulled the other end tight, while her right hand used a sharp stone tool to scrape off easier-to-chew chunks. When her right hand slipped, the tool would have scraped her teeth, leaving diagonal grooves. 
  
 A) A right-hander pulls with the left and cuts with the right. B) Dense concentrations of striations show that the tooth surface was repeatedly modified by a stone tool. Image: David Frayer 
  
 The anthropologists tallied 559 total marks on the six front teeth. About 47 percent of the scratches were slanted in the direction of a right-handed cut. About 11 percent of the scratches slanted the opposite direction, reflecting a left-handed cutting motion. The remaining scratches were horizontal or vertical. 
  
 "These teeth were used as platforms to process materials, and so there were lots of different scratches," Frayer said. 
  
 But the right-handed scratches were disproportionately high and statistically significant, leading the researchers to conclude that the jaw's owner was most likely right-handed. 
  
 It's possible that Frayer and his colleagues have misinterpreted these scratches. 
  
 Bernard Wood, a paleoanthropologist at George Washington University who was not part of the study, told the Christian Science Monitor that Frayer and his colleagues might be jumping to conclusions. 
  
 "My concern is that they really don't spend enough time on other explanations for these phenomena, the presence of these scratches and their directionality," Wood said. 
  
 "It's a really interesting observation that only time will tell whether that observation has been over-interpreted." ||||| Labial striations on the anterior teeth have been documented in numerous European pre-Neandertal and Neandertal fossils and serve as evidence for handedness. OH-65, dated at 1.8 mya, shows a concentration of oblique striations on, especially, the left I1 and right I1, I2 and C1, which signal that it was right-handed. From these patterns we contend that OH-65 was habitually using the right hand, over the left, in manipulating objects during some kind of oral processing. In living humans right-handedness is generally correlated with brain lateralization, although the strength of the association is questioned by some. We propose that as more specimens are found, right-handedness, as seen in living Homo, will most probably be typical of these early hominins. |||||
A:
A lot has changed over 1.8 million years, but perhaps not the tendency of hominids to favor their right hand. An upper jawbone belonging to a human relative who lived in what is now Tanzania almost 2 million years ago has been discovered with scratches on its still-intact teeth, and scientists have a clear idea about how they were made: by a stone tool held in the Homo habilis individual's right hand. Why is that significant? Well, it represents the earliest known evidence of right-handedness among human relatives. The next oldest comes from the 500,000-year-old teeth of a Homo heidelbergensis individual, per National Geographic. Evidence also suggests Neanderthals were predominantly right-handed. In the case of Homo habilis, archaeologists think the teeth nicks came about thusly: The individual would have a piece of meat clenched in his teeth, and while he stretched it out with one hand, he used the other, dominant, hand, to cut it with a stone, explains Live Science. (It provides a graphic of what this looks like.) Occasionally, the stone would slip, and the direction of the resulting nicks suggests the right hand was the one used, a theory backed up in modern experiments. Few studies have analyzed Homo habilis teeth for such marks, but study author David Frayer of the University of Kansas hopes his research will encourage others to do just that. The discovery may also offer insights about when language first appeared since "language, handedness, brain laterality ... are all interrelated," he tells Mashable. (This is the oldest evidence of human cancer.)