A new study, led by a Binghamton University anthropologist and published this week by the National Academy of Sciences, could shed new light on the earliest existence of humans. The study analyzed the tiny ear bones, the malleus, incus and stapes, from two species of early human ancestor in South Africa. The ear ossicles are the smallest bones in the human body and are among the rarest of human fossils recovered.
Unlike other bones of the skeleton, the ossicles are already fully formed and adult-sized at birth. This indicates that their size and shape is under very strong genetic control and, despite their small size, they hold a wealth of evolutionary information.
The study, led by Binghamton University anthropologist Rolf Quam, was carried out by an international team of researchers from institutions in the US, Italy and Spain. They analyzed several auditory ossicles representing the early hominin species Paranthropus robustus and Australopithecus africanus. The new study includes the oldest complete ossicular chain (i.e. all three ear bones) of a fossil hominin ever recovered. The bones date to around two million years ago and come from the well-known South African cave sites of Swartkrans and Sterkfontein, which have yielded abundant fossils of these early human ancestors.
The researchers report several significant findings from the study. The malleus is clearly human-like, and its size and shape can be easily distinguished from our closest living relatives, chimpanzees, gorillas and orangutans. Many aspects of the skull, teeth and skeleton in these early human ancestors remain quite primitive and ape-like, but the malleus is one of the very few features of these early hominins that is similar to our own species, Homo sapiens. Since both the early hominin species share this human-like malleus, the anatomical changes in this bone must have occurred very early in our evolutionary history. Says Quam, "Bipedalism (walking on two feet) and a reduction in the size of the canine teeth have long been held up as the "hallmark of humanity" since they seem to be present in the earliest human fossils recovered to date.
Our study suggests that the list may need to be updated to include changes in the malleus as well." More fossils from even earlier time periods are needed to corroborate this assertion, says Quam. In contrast to the malleus, the two other ear ossicles, the incus and stapes, appear more similar to chimpanzees, gorillas and orangutans. The ossicles, then, show an interesting mixture of ape-like and human-like features.
The anatomical differences from humans found in the ossicles, along with other differences in the outer, middle and inner ear, are consistent with different hearing capacities in these early hominin taxa compared to modern humans. Although the current study does not demonstrate this conclusively, the team plans on studying the functional aspects of the ear in these early hominins relying on 3D virtual reconstructions based on high resolution CT scans. The team has already applied this approach previously to the 500,000 year-old human fossils from the Sierra de Atapuerca in northern Spain. The fossils from this site represent the ancestors of the Neandertals, but the results suggested their hearing pattern already resembled Homo sapiens. Extending this type of analysis to Australopithecus and Paranthropus should provide new insight into when our modern human pattern of hearing may have evolved. The study has just been published in the Proceedings of the National Academy of Sciences.
To view, visit: http://www.pnas.org/content/early/2013/05/08/1303375110.full.pdf+html?sid=5497ce62-ef90-4d7b-b363-e707effb0318
Ryan Yarosh | EurekAlert!
Climate change weakens Walker circulation
20.10.2017 | MARUM - Zentrum für Marine Umweltwissenschaften an der Universität Bremen
Shallow soils promote savannas in South America
20.10.2017 | Senckenberg Forschungsinstitut und Naturmuseen
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
20.10.2017 | Information Technology
20.10.2017 | Materials Sciences
20.10.2017 | Interdisciplinary Research