OH 89 collar bone discovery announced by Olduvai Gorge archaeological team
In 2005, a team of scientists with the Olduvai Gorge Conservation Project (OCV) discovered two hominin clavicles. The discovery was made just above the surface, “near the FLK North locality, eroding from upper Bed 1, just below tuff 1…” (ref. biorxv.org). The first clavicle OH 48, dated 1.83 million years ago (mya) is undetermined. But researchers recently completed an extensive, and relatively conclusive study of OH 89.
Most Americans are familiar with the clavicle, which is a common bone fractured in football injuries.
Quick reference from Britannica:
The clavicle is a common site of fracture, particularly at the midsection of the bone; horizontal impact to the shoulder, such as from a fall or trauma, is a common cause.
The research team analyzing the clavicle is led by world-renowned archaeological professor Fidelis Taliwawa Masao of the University of Dar es Salaam. Other members of the team include Agustino Venance Songita, also of the Univ. of Dar es Salaam, Catherine E. Taylor PhD of the University of California at Berkeley and paleoanthropologist Jackson N Njau, (photo) principal curator at the Museum of National Natural History in Arusha, Tanzania.
From the paper at Biorxiv, Feb. 3,
OH 89: A newly described ~1.8-million-year-old hominid clavicle from Olduvai Gorge
In summary, our analyses demonstrate that OH 89 is, for the most part, on the edge of the range of variation of human clavicular variation despite its antiquity. Although researchers occasionally assign fragmentary, isolated postcrania to species, such a taxonomic identification is not possible for OH 89.
Based on other fossil evidence, we know that around ~1.8 Ma, there were at least two distinct species of hominids living around Olduvai Gorge (Blumenschine et al., 2012; Clarke, 2012; Domínguez-Rodrigo et al., 2015). While it is impossible to decisively say what species OH 89 and OH 48 belonged to, or if they are even conspecific, the discovery of OH 89 does reveal that hominid clavicles show notable similarities to modern humans at least as far back as 1.8 Ma.
The two hominin species alluded too, but not specifically mentioned by the paper’s authors are of course, Homo habilis and Paranthropus Bosiei.
Background: Around 4 to 6 million years ago, the earth’s climate began to shift. The landscape in Africa, particularly northern Africa was greatly affected. What were formerly deep tropical forests became grasslands with sparse forested pockets. Early hominin species such as Ardipithecus ramidus co-discovered by Tim White of UC-Berkeley, evolved into Australopithecines. The Australopiths were better adapted to the new environment. One branch of Australopithecines developed a diet of tubers and other vegetation that required larger chewing muscles and back teeth. They became the Paranthropus line, including the famous Paranthropus Bosiei discovered by Mary Leakey in 1959 nicknamed “Zinj.”
Note – Paranthropus Boisei was named after the philanthropist and British diamond miner Charles Boisei who funded Louis and Mary Leakey’s expeditions,
Could be Paranthropus Boisei, but study authors hint strongly it’s Homo habilis
Like other members of the Paranthropus genus, P. boiseiis characterized by a specialized skull with adaptations for heavy chewing. A strong sagittal crest on the midline of the top of the skull anchored the temporalis muscles (large chewing muscles) from the top and side of the braincase to the lower jaw, and thus moved the massive jaw up and down. The force was focused on the large cheek teeth (molars and premolars)…
[With] Mary Leakey’s 1959 discovery of the ‘Zinj’ skull (OH 5) that scientists knew what they had found was a new species. ‘Zinj’ became the type specimen for P. boisei and, soon after, arguably the most famous early human fossil from Olduvai Gorge in northern Tanzania.
The other branch of Australopithecines evolved into the famous Lucy, Australopithecus afarensis, as well as Australopithecus africanus, and later Australopithecus sediba. One of lines of Australopithecines, very possibly A-Sediba, evolved into the first species of genus Homo – Homo habilis, the handy man.
Homo habilis, “handy man,” is so called because of the wealth of tools that have been found with its fossils. The average H. habilis brain was considerably larger than the average Australopithecus brain. The brain shape is also more humanlike. The bulge of Broca’s area, essential for speech, is visible in one H. habilis brain cast, indicating that the species may have been capable of rudimentary speech. The average H. habilis individual is thought to have been about five feet tall and 100 pounds, although females may have been smaller.
Very few skeletal fossils have been recovered for Homo habilis. Though, fortunately two fragmented skulls have been found, and a number of teeth. One of the Habilis skulls was of course, the famous OH 7 was discovered by Jonathan, son of Mary and Louis Leakey. The second, OH 62, skull fragments and parts of the hand, were discovered by the Tim White team, led by Donald Johanson in 1986.
(Note – OH is the abbreviation for Olduvai Hominin. Olduvai Gorge shown in the photo).
The paper’s authors are cautious, not explicitly identifying OH 89 as Homo habilis. But the implication is strong.
OH 89, a 1.8 Ma hominid clavicle, falls within the range of modern humans in absolute size and clavicular curvature. This finding indicates that there has been little morphological change in the hominid clavicle in the last ~2 million years.
“Within the range of modern humans,” would indicate not Paranthropus Bosei, but rather genus Homo. As the authors note, that would strongly suggest, that the shoulder and collar bones of modern humans were already set as of 1.8 million years ago.
For a good short intro to Homo habilis, Habella at YouTube. H/t for cover photo.