Stony Brook-led research demonstrates how upper body motion contributed to walking proficiency in our early human ancestors
A research team led by Stony Brook University investigating human and chimpanzee locomotion have uncovered unexpected similarities in the way the two species use their upper body during two-legged walking.
Nathan Thompson, Lucille Betti-Nash, and Deming Yang
This image depicts pelvis and ribcage rotations during bipedal locomotion. Despite differences in overall motion, there is as much mobility between the pelvis and ribcage in humans as in chimpanzees, suggesting more human-like abilities in our earliest ancestors than previously thought.
The results, reported in Nature Communications, indicate that our early human ancestors, including the famous fossil ‘Lucy’ (a species known as Australopithecus afarensis), may have been able to use their torsos to increase walking efficiency in the same way as modern humans.
The torso (the part of the body that includes the ribcage, belly and pelvis) of chimpanzees has long been thought to be a rigid block, best suited for a life of tree climbing. Humans, on the other hand, have long and flexible torsos that aid in walking by allowing us to rotate our upper body in the opposite direction of our lower body.
The findings from the paper, titled “Surprising trunk rotational capabilities in chimpanzees and implications for bipedal walking proficiency in early humans,” changes the evolutionary view of how early human ancestors walked and what they were able to do.
“During walking, we actually observed as much rotation within the torsos of chimpanzees as in humans,” said Nathan Thompson, lead author and a PhD student in the Department of Anatomical Sciences at Stony Brook University.
“This means that the widely accepted assumptions in the scientific community about how the chimpanzee torso works based on the skeleton alone are incorrect. Our results also point to the notion that a limitation to upright walking that we thought affected Lucy and other early human ancestors probably was not a limitation at all.”
The research team used high-speed cameras to track and compare how the torsos of humans and chimpanzees actually moved during bipedal walking. They studied the movements by way of three-dimensional kinematic analyses and computer-generated comparisons.
They discovered that the main difference between human and chimpanzee bipedalism is that chimps swing their hips much more.
“Only when our early ancestors were able to reduce this hip rotation were their upper bodies able to play a human-like role in promoting efficient bipedal walking,” said Thompson. “When this actual transition occurred is still an open question.”
There is a continuing debate about how the hips of our ancestors worked compared to ours.
“For instance, depending on who you ask, the 3.2 million-year-old Lucy fossil either rotated her pelvis exactly like modern humans or up to 2.5 times more,” he explained.
Given this uncertainty, the research team modeled the transition from a more chimp-like pattern of the upper body movement to that of a more human-like pattern. They found that even if Lucy rotated her pelvis 50 percent more than modern humans, her upper body would have functioned essentially like ours. This means that even as early as 3.2 million years ago Lucy might have been able to save work and energy in much the same way as humans do today.
“As we get a better idea of how our closest living relatives move, we are able to learn much more about the isolated piles of early human bones that the fossil record leaves us,” added Thompson. “Only then can we paint a complete picture of how we evolved into what we are today.”
Co-authors on the paper include Susan Larson, Brigitte Demes, and Nicholas Holowka of Stony Brook University, and Matthew C. O’Neill of the University of Arizona.
The research was funded by the National Science Foundation and The Leakey Foundation.
Manager of Media Relations, School of Medicine
Gregory Filiano | newswise
Colorectal cancer risk factors decrypted
13.07.2018 | Max-Planck-Institut für Stoffwechselforschung
Algae Have Land Genes
13.07.2018 | Julius-Maximilians-Universität Würzburg
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
13.07.2018 | Event News
13.07.2018 | Materials Sciences
13.07.2018 | Life Sciences