Study Suggests 3.2 Million-Year-Old Lucy Spent a Lot of Time in Trees

Dec 4, 2016

By Joanna Klein

Lucy was a small one. She weighed about as much as the average 2nd grader and stood about three-and-a-half feet tall. But that lady (or pre-lady, because Australopithecus afarensis like her weren’t quite human) was strong. Her famous skeleton, a 3.18 million-year-old fossil also known as AL 288-1, tells us so. But to build arm bones as strong as hers, she, and possibly other members of her species, probably spent a lot of time in trees, suggests a study published Wednesday in the journal PLOS One.

Lucy, discovered almost half a century ago, was the most complete skeleton of the earliest hominid ever found at the time. She changed our understanding of human evolution. There’s little doubt Lucy walked on two feet like a modern human, or that she climbed trees to sleep, avoid predators or gather food. Some scientists — including some involved in this study — even think she died after a fall from one. But just how much time she spent in trees has been a subject of contention because interpretations of her ancient skeletal clues are hard to prove. For the latest study, researchers looked at the ways bones can grow stronger or weaker with everyday use. And by examining the internal structure of Lucy’s upper right arm and leg bones and comparing them with the bones of around 100 chimpanzees and 1,000 modern humans, they concluded that climbing trees wasn’t just some trivial task. Lucy did it enough that the ratio of strength between her arms and legs is slightly more chimpish than human.

“That doesn’t mean she was acting like a chimp, just that she was stressing her limbs more like a chimpanzee than a modern human,” said Christopher Ruff, a paleoanthropologist at Johns Hopkins University who led the study.


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2 comments on “Study Suggests 3.2 Million-Year-Old Lucy Spent a Lot of Time in Trees

  • @OP – But that lady (or pre-lady, because Australopithecus afarensis like her weren’t quite human) was strong.
    Her famous skeleton, a 3.18 million-year-old fossil also known as AL 288-1, tells us so.

    Lucy, discovered almost half a century ago, was the most complete skeleton of the earliest hominid ever found at the time. She changed our understanding of human evolution.
    There’s little doubt Lucy walked on two feet like a modern human, or that she climbed trees to sleep, avoid predators or gather food. Some scientists — including some involved in this study — even think she died after a fall from one.

    However, DNA analysis can take us even further back in evolution.

    http://www.bbc.co.uk/news/science-environment-38226810

    Humans may in part owe their big brains to a DNA “typo” in their genetic code, research suggests.
    The mutation was also present in our evolutionary “cousins” – the Neanderthals and Denisovans.

    However, it is not found in humans’ closest living relatives, the chimpanzees.

    As early humans evolved, they developed larger and more complex brains, which can process and store a lot of information.

    Last year, scientists pinpointed a human gene that they think was behind the expansion of a key brain region known as the neocortex.

    They believe the gene arose about five or six million years ago, after the human line had split off from chimpanzees.

    Now, researchers have found a tiny DNA change – a point mutation – that appears to have changed the function of the gene, sparking the process of expansion of the neocortex.

    It may have paved the way for the brain’s expansion by dramatically boosting the number of brain cells found in this region.

    Dr Wieland Huttner of the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, Germany, led the research.

    “A point mutation in a human-specific gene gave it a function that allows expansion of the relevant stem cells that make a brain big,” he told BBC News.

    “This one, as it is fixed in the human genome – so all living humans have the gene – apparently gave a tremendous selection advantage, and that’s why we believe it spread in the human population.”

    Between two and six million years ago, the ancestors of modern humans began to walk upright and use simple tools.

    During this extended period of time, their brain size started to increase. They began to spread around the world, encountering different environments.

    From about 800,000 years ago, their brain size increased further, helping them to survive in a changing world.

    Still, many questions remain about how early humans evolved larger brains.

    It is likely that the gene is one of many genetic changes that gave humans their unique intelligence and thinking ability.

    The research is published in the journal, Science Advances.



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