The supraorbital torus (or brow ridge) is a very distinctive morphological trait in most of our hominin ancestors. What purpose does this feature serve? A few theories around this topic are:
- Dissipation of heavy chewing forces, produced by the jaw muscles and transmitted around the nose and the eye sockets.
- Reinforcement of the frontal bone which was weaker in all the hominin species before Homo sapiens. This is a similar idea to explain the development of the chin in modern humans, as a reinforcement of a weaker jaw.
- Protection of the skull and the eyes against blows.
- A signaling effect, accentuating aggressive stares, thus its large size could have been sexually selected through generations.
However, many huge supraorbital tori are hollowed inside with large sinuses (for example: Petralona), suggesting that they did not bear or transmit physical forces from blows to the head or heavy chewing. I like the idea to think about a combination of several factors which made evolution work for a few million years. This post describes the supraorbital tori of 22 iconic hominins:
Al 444-2: The largest Australopithecus afarensis skull yet discovered has an expansive supraorbital torus, thickened laterally and continuous superiorly-posteriorly with no interruption.
Sts 5 (Mrs. Ples) has a relatively small supraorbital torus, double arched in the front and projecting glabella. Another Au. africanus skull with many similarities is Sts 71, with a less broad torus in comparison to Sts 5, but with a similar expanded glabella.
Supraorbital torus: Sts 5 (centre)-credit Wikipedia, AL 444-2 (left) and Sts 71 (right)-credit Roberto Sáez
In this interview for Nutcracker Man, Chris Stringer addresses some key recent discussions in the human evolution field, such as:
- The origin of the anatomically modern humans. The frontier between ‘archaic’ and ‘modern’ Homo sapiens.
- Reassessment of the Homo heidelbergensis species.
- Early and late dispersals of modern humans outside Africa.
- Behavioural modernity vs. Anatomical modernity.
Finally, he talks about a new book he is working on.
Chris Stringer is one of the most important researchers in the field of human evolution. He is Research Leader in Human Origins at the Natural History Museum and previously director of the Ancient Human Occupation of Britain project. His work is searchable on the Museum’s website and you can follow him on twitter.
Interview with Chris Stringer. Photo: Roberto Sáez
1. The origin of the so-called anatomically modern humans is not so clear now in the post-Neanderthal genome era. In 2016, you argued a new paradigm by setting the origin of our species Homo sapiens back to 500 K years ago rather than 200 K. What is the rationale for that? What is for you an ‘archaic’ Homo sapiens? And what is the frontier between ‘archaic’ and ‘modern’ Homo sapiens?
This is a nice and rare illustration by Bonnie Miljou of Zinjanthropus boisei (‘Zinj’), the species defined by Louis Leakey for the iconic fossil OH 5 – later assigned to Paranthropus boisei. Due to the hyper-robust morphology of its dentition, OH 5 was nicknamed ‘Nutcracker Man’, which gives the name to this blog.
The morphology of this cranium is clearly associated with the masticatory function. In particular, the illustration highlights 5 features:
Zinjanthropus boisei. Illustration by Bonnie Miljou
Finally! The 3rd edition of my little tradition, a particular ‘annual report’: the list of my favorite hominin #FossilFriday tweets in 2016, from number 10 to 1.
For those who do not know what “FossilFriday” means… Every Friday on twitter, people share pics of their favorite fossils, related scientific papers or blog posts, by using the hashtag #FossilFriday. This is a great manner to show famous or rare pieces of museum collections, and to share research works. I join every Friday and tweet about a different hominin fossil. Now, let’s start!
10. Look into the 1.8 Ma eyes of the impressive OH 24 | MNCN Colecciones
“Every time I see the name ‘Homo heidelbergensis’ I feel a little queasy”, John Hawks
Homo heidelbergensis was defined in 1908 as a new species for a mandible that was found one year before, by the Neckar river in Mauer, near Heidelberg in Germany. This mandible, dated to 600 Ka, was the oldest hominin fossil in Europe for the following 90 years.
In the meantime, the name Homo heidelbergensis remained with no further assignment to any other fossil for seven decades, until it was resurrected to try to classify a group of 20+ specimens of the Middle Pleistocene from dispersed sites in Europe (Arago in France, Petralona in Greece…), Africa (Kabwe in Zambia, Bodo in Ethiopia…) and Asia (Yunxian and Dali in China…). They all had in common some derived features from Homo erectus, basically a larger brain which reflects in complex tools (e.g. the wooden spear fron Schöningen, Germany).
“In reality this species should have stayed dead instead of being resurrected in the 1980s”, Juan Luis Arsuaga
They were ‘archaic Homo sapiens’, fossils dated to between 600 Ka and 200 Ka just before the Homo sapiens appeared in Africa. It was made necessary to assign them to a species which demonstrated an evolutionary path between erectus and modern humans, being also ancestor of neandertals. Homo heidelbergensis was the choosen name, although there was not any complete description of this species.
The following three iconic hominins were found on October 21st!
The Mauer mandible – Oct 21st, 1907
It was found in the sediments by the Neckar river near Mauer, Germany, and dated to 500-600 Ka. The fossil was so different from other Homo specimens that a new species was defined for it: Homo heidelbergensis. This mandible remained the oldest hominin known in Europe for almost a century, until the 1990s.
It combines primitive features (large size, robust wide mandibular body, thick enamel, broad ramus) and modern features (molars are smaller than Homo erectus but some similar to modern humans). It is relatively short, the symphysis slopes down and back from the teeth and lacks a projecting chin.
Mauer mandible. Image credit: Schoetensack O. Der Unterkeifer des Homo heidelbergensis aus den Sanden von Mauer bei Heidelberg (1908)
The 6th annual meeting of the European Society for the study of Human Evolution (ESHE) took place in Alcalá de Henares, near Madrid, Spain on September 15-17th 2016. This is a summary of most of the presentations that I attended, sorted by the number of engagements in twitter. Click on the podium pictures to enlarge. Contact me if you are missing any other lecture or need further information.
Alcalá de Henares, Plaza Cervantes. Photo: espaciomadrid.es
Sima de las Palomas del Cabezo Gordo is a vertical cave in Murcia (southeastern Spain), that is one of the most remarkable neandertal sites in Western Europe. Since 1991 it has yielded remains from at least 9 neandertal individuals, including 3 nearly complete articulated skeletons, among many other objects that also help to explain the ecology of the human populations in the area at least 50,000 years ago. The 2016 campaign is important as new fossils have been found at the deepest layers dated to 65-90 Ka.
The 3 skeletons
Between 2005-2009 three undisturbed neandertal skeletons with several parts in anatomical position were recovered:
- An adult woman (SP96) and a child beneath her (SP97), both with the knees flexed and the elbows and hands raised up beside the face.
- Another adult individual (SP92) with an extended elbow was beneath the child.
- The 3 skeletons are dated to 50 Ka by U-series.
- Many large stones and flakes were located over the skeletons. They might have been thrown to deter leopards and hyenas from disturbing the corpses.
- The skeletons were lying in a cemented rock tumble, together with some burnt articulated horse ankle bones, 9 Mousterian tools, 12 flakes and 100 fragments of knapping waste.
- Most of the human bones do not show any cut marks nor burnt residues.
- However, the woman was deposited over a layer where a large fire was made before.
- Near the child, two articulated leopard paws were found.
There could be an intentional arrangement of the bodies before rigor mortis, although there is no burial pit or other clear-cut signs.
Sima de las Palomas. Neandertal child SP97. Laboratory removal of adherent breccia with vibroscalpels continues. CAT scan of SP97 cranium revealed some hidden hand bone fragments close to the forehead. Photo credit: MUPANTQUAT