October 4, 2012

Folic acid deficiency detected in Olduway c. 1.5 Ma ago

The headlines and even contents in commercial media and blogs alike are all about meat eating (much of which must be blamed on the lead researcher himself, who seems to have a bias) but it does not need to be the reason at all and rather reflects an ideological bias. 

All that paleoanthroplogists have detected is a folate deficiency in a fragment of a skull of what is probably an Homo erectus/ergaster young child (est. 2 y.o. or less) from East Africa. There is no dietary isotope research that can confirm or deny the meat hypothesis.

Manuel Domínguez-Rodrigo et al., Earliest Porotic Hyperostosis on a 1.5-Million-Year-Old Hominin, Olduvai Gorge, Tanzania. PLoS ONE 2012. Open access ··> LINK [doi:10.1371/journal.pone.0046414]

The authors found exactly this:

Figure 3. Ectocranial (top right) and endocranial (top left) close-up views of the OH 81 fossil, accompanied by magnifications of the porotic hyperostosis paleopathology as observed ectocranially (lower left) and edge-on at the diploic-table junction (lower right).
Scale = 1 mm.

They conclude that this porosity of the bone, known as porotic hyperostosis, should indicate folate deficiency (in which vitamins B9 and B12 are involved) caused by malnutrition. They also argue that weaning may have been a cause because, at least in other contexts, it is a key period for nutritional illnesses, often implying B12 deficiency. 

The archaeo-environmental context (persistent drought) may have contributed to this illness and death as well.

Still the emphasis in meat eating, even if possibly correct, strikes me as very ideological:

The presence of anemia-induced porotic hypertostosis on the 1.5 Ma OH 81 hominin parietal, indicates indirectly that by at least the early Pleistocene meat had become so essential to proper hominin functioning that its paucity or lack led to deleterious pathological conditions. 

Were do we get that from, Dr. Domínguez? Some sort of nutritional lack seems obvious but there are many reasons why folate deficiency can develop; for example excess of solar radiation (it has been proposed that the ancestral dark skin of humans serves to prevent folate loss, rather than cancer, which only develops in the long term). Was this child an albino maybe? 

Or had it celiac disease (another possible cause of malabsorption)?

And (update), as the Subersive Archaeologist discusses rather emotionally, the maybe simplest explanation: that malaria could be the cause is dismissed in the paper without satisfactory explanation.

Sure thing that lack of sufficient animal protein intake is a plausible cause but by no means demonstrated. An isotopic analysis could support or reject this hypothesis, although I am uncertain if it is possible to perform on this particular bone.


See also labels Paleolithic food, human evolution and pigmentation in this blog.


Update (Oct 10): I just got to know that there is a formal criticism by two anthropologists, J.J. Crandall and D.L. Martin, roughly in the same line as mentioned here. Read it here.

Update (Oct 16): Domínguez at al.  replied to the previous criticism here. However their only argument against a malaria-caused PH is:

PH still occurs in much lower frequencies on skeletons in this earlier transitional period than is observed in more recent skeletal populations from the sedentary, agrarian Neolithic.

... what fails to be conclusive.

2 comments:

  1. Hi, Maju.
    You can probably guess what I think of this claim...
    http://www.thesubversivearchaeologist.com/2012/10/porotic-hyperostosis-or-how-to-flimflam.html
    Thanks for keeping us posted.

    ReplyDelete
    Replies
    1. In this case I agree with you, Rob.

      Notably I was undecided whether to include malaria among the possible causes but their statement was so vague and the information I could find on the malaria-hyperostosis relation was zero, that I decided to skip it altogether.

      But the way you excerpt it clearly underlines how a possible cause was ignored. Of course the hyperostosis is found in other circumstances but Domínguez totally ignores it, jumping to gut parasites as if all parasites would be the same thing.

      Delete

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