Essay Season is here!

Having recently published one piece of my Masters’ coursework on this blog, the time feels right to share the other fruits of my intensive one-year taught programme! What use, after all, is my work when it simply resides on the hard-drive of my laptop? Better surely to bring it to light like a long-buried hominin fossil?!

As such, the coming days on The Human Story will be characterised by a number of 3000-word postings that constitute the essays, reports and critiques that I completed during my MSc in Palaeoanthropology at the University of Sheffield. Each is the product of two or more week’s hard graft spent toiling through pulse-racing primary literature!

The first article in the series was produced for a module entitled Evolutionary Primatology. This review paper examines the evolution of the primates (including specific lineages) amidst the ever-changing structure of the earth’s land masses and continents aka biogeography.

Bipedalism (the ability to walk on two feet) is the focus of the second installment which acted as a critical component to another module, Human Osteology. This essay looks in closer detail at the human skeleton to identify the evolutionary signatures of our upright stance and posture. Using the Great Apes and extinct hominins as comparative specimens, the nature of the musculoskeletal (muscular and skeletal) changes that occurred during human evolution is revealed.

Beware readers and prospective Palaeo’ students – correctly cite the above content and for personal use only! I have posted these articles as a good gesture. They should be used as reference material for obtaining background information. As a guide, citing any works published on a blog looks decidedly dodgy on any piece of post A-level, university work. Even a mildly competent plagiarising screen will discover your copy and pasting naughtiness.

Evolutionary Anthropology: an authoritarian review journal?

Evolutionary Anthropology happens to be one of my favourite journals. Tailored more specifically than any other to the fields of human evolution, biological anthropology and archaeology, this journal pumps out bimonthly issues for researchers and interested others such as myself to slobber over.

However, whilst every cloud may have a silver lining, Evolutionary Anthropology also has dark sides. In this case there are two. One is that Evo Anth (to abbreviate) is managed by Wiley Online Library which funnily enough isn’t an open-access publisher. Authors and funding agencies do have the option to publish an article as open-access… but only at the hefty expense of $3,000. Extortionate!

Secondly, Evo Anth is an invite-only publication. On the face of it this may seem appropriate given that it is a quality-assured method. On the other hand, surely this closed culture can only serve to forge cliques in the field, preventing both budding researchers and controversial colleagues from contributing to its print?

Self-labelled as an “authoritative review journal”, Evo Anth may perhaps be better described as an “authoritarian review journal“.

Lagar Velho: a genuine Neanderthal-Modern Human hybrid?

Back in 1999 a juvenile skeleton was recovered from a limestone cliff site in central Portugal. The skeleton, which was the subject of intentional burial, was painted in red ochre and the grave was decorated with animal bones. Milk teeth found in the fossilised jaw [Photo 1] provided an age estimation of 4 yearsDated remains of charcoal, and bones of red deer and rabbit found in close proximity to the skeleton approximate the burial age at 24,500 years ago.

Dentition of the Lagar Velho skeleton. Note the unerupted molars and the prominent but reclining development of the chin. Source: Duarte et al., 1999.

Dentition of the Lagar Velho skeleton. Note the unerupted molars and the prominent but reclining development of the chin. Source: Duarte et al., 1999.

Known as Lagar Velho 1 and/or Lapedo child, the skeleton was described as bearing a mixture of modern human and Neanderthal features – known as a morphological mosaic [Table 1]. In common with our species Homo sapiens, Lagar Velho child has a developed mental osseum (chin), which is a feature unique to our species. Tooth measurements and dimensions of the pubic (pelvic front) also align the child with our own species.

Table 1. Mixture of features displayed in Lagar Velho 1 skeleton

Modern Human

Neanderthal

Chin development

Dental dimensions

Mandibular features

Radial features (curvature, tuberosity orientation)

Pubic proportions

Chin orientation

Femoral robusticity

Femur:tibia length

Muscle attachment sites (pectoralis major insertion)

Tibial robusticity

 

However, the aforementioned chin slopes backwards as in archaic species like Neanderthals rather than the forward projection reminiscent of our own [Photo 1]. What’s more, Lagar Velho is similar to Neanderthals in measurements of the lower limb bones. Neanderthal leg bones are more sturdy and stocky than our own, possibly as an adaptation to a cold climate. Could Lagar Velho prove to be a bona fide example of a Neanderthal-modern human hybrid? 

Considerations

1) Modern humans equipped with their Upper Palaeolithic toolkit were invading Europe nearly 45,000 years ago, although the Iberian peninsula remained a Middle Palaeolithic landscape until much later. Evidence of Neanderthal occupation at Gorham’s Cave in Gibraltar, extends to 26,000 years ago. Therefore a potential overlap in population ranges can be implied.

2) Tattersall and Schwartz argue against the author’s (Duarte et al., 1999) conclusions in in the same edition of PNAS in which the original publication appeared. In their view the Lagar Velho 1 skeleton was simply that of a “chunky Gravettian child” from a modern human population. All the ambiguous Neanderthal-like morphological features are accounted for.

3) The Lagar Velho finds came to light 11 years before scientists announced the revelatory genetic signatures of Neanderthal-Modern Human interbreeding. However, new research suggests that conclusions of hybridisation based on genetic studies should be made with caution. Models need to instead account for population structure. Only the successful extraction and examination of ancient DNA from the Lapedo child will resolve the matter once and for all.

Reference: Duarte, C. et al., 1999.  The early Upper Paleolithic human skeleton from the Abrigo do Lagar Velho (Portugal) and modern human emergence in Iberia. PNAS 96: 7604-760 9

A fountain of questions offered by our latest ancestor

Despite the assertions made and many matters resolved by the new research on Australopithecus sediba, questions remain unanswered. How, for example, does Sediba compare to other extinct human species such as “handy man” Homo habilis? Sediba’s brain volume is well short of handy man’s 600cc, who also appears at earlier dates of 2.3 million years ago. Following the news that stone tools predate the genus Homo, what characteristics actually define our genus? Where to draw the line between Australopithecus and Homo? How can Sediba give rise directly to H. erectus when the latter’s brain capacity averages of 850cc? Where do the contemporary Dmanisi fossils fit into this updated story of human evolution?