July 24, 2012

Broken Hill humerus: date unknown

Recently it was hinted that the Broken Hill skull is younger than has been thought before. Now, a brief communication by Erik Trinkaus in AJPA suggests that the BH humerus which has featured in debates about the evolution of human postcranial morphology lacks proper stratigraphic context, and is from a location where modern human disturbance is likely. The conclusion: it should be avoided in studies about the evolution of humans until it is securely dated.

Redating fossils is a problem that has plagued anthropology for a while. For example, H. sapiens idaltu (Herto) was given a Linnaean moniker and recognized as a precursor of modern humans because of its mix of modern and archaic traits, but shortly thereafter the Omo skulls were re-dated to tens of thousands of years earlier (~195ka), indicating that the more modern morphology of Omo I actually preceded the more archaic one of Herto Man.

When an older fossil is redated to a younger age, what was once seen as showing signs of evolutionary trends leading up to modern humans ends up being an embarrassing survival of archaic traits in a period where they are supposed to have been on their way to replacement. The once popular story of modern humans shedding their archaic traits and attaining modernity in Africa, and then populating the world is increasingly unbelievable, both because the 60,000-year-old coastal migration is bunk, but also because archaic traits persist in some African populations down to the Holocene. I strongly suspect that the story of our origins may be much more interesting than anyone had imagined.

AJPA DOI: 10.1002/ajpa.22118

Brief communication: The human humerus from the broken hill mine, kabwe, zambia

Erik Trinkaus et al.

The distal half of a right human humerus (E.898), recovered ex situ in 1925 by Hrdlicka at the Broken Hill Mine, Kabwe, Zambia, has figured prominently in assessments of Middle Pleistocene Homo postcranial variation and of the phylogenetic polarity and functional anatomy of Pleistocene Homo upper limb morphology. Reassessment of distal humeral features that distinguish modern human and some archaic Homo humeri, especially relative olecranon breadth and medial and lateral pillar thicknesses, confirm previous studies placing it morphologically close to recent humans, as well as possibly to Early Pleistocene Homo. However, it completely lacks stratigraphic context, and there is faunal and archeological evidence for human activity at Broken Hill from the Middle Pleistocene to the Holocene. Given its uncertain geological age and modern human morphology, the Broken Hill E.898 humerus should not be used in analyses of Pleistocene humans until it is securely dated. Am J Phys Anthropol, 2012. © 2012 Wiley Periodicals, Inc.


1 comment:

terryt said...

"I strongly suspect that the story of our origins may be much more interesting than anyone had imagined".

And gets more interesting by the day.

"because the 60,000-year-old coastal migration is bunk"

Someone (I think it was South Central Haplo) way back asked me why I was on about the coastal migration theory all the time. So after all this time I can finally say, 'I told you so'.