From: Analysis of animal remains from archaeological sites [mailto:[log in to unmask]] On Behalf Of GREG CAMPBELL
Sent: Friday, 1 November 2013 12:08 a.m.
To: [log in to unmask]
Subject: [ZOOARCH] Size prediction formulae

Predicting original sizes of animals from the parts that survive archaeologically is a daily task for archaeozoologists.  It’s not inherently bad that most of the formulae we use are three, four or five generations old.  What can be bad about the formulae is that they assume shape is constant regardless of size.  For example, if you calculate shoulder height by multiplying humerus length by some number, you  are assuming that number (the proportion of shoulder height to humerus length) is constant for all shoulder heights.  This is bad because that proportions is almost never constant; we all know from experience that animal shape is not constant, it varies with size (the calf is not the same build as the cow, the foal is not the same build as the horse, etc.).  So most animals change shape as they change size: they exhibit allometric growth.  So insisting on simple proportions won't work well.

Also, there are large numbers of dimensions that can be measured on an animal's bones, or even on a particular bone, so it is difficult to know which dimension is the best predictor of size, and whether using more than one dimension would give better predictions. 

This has been a concern of mine for over a decade.  I have recently published a paper on how to derive accurate size reconstruction formulae from surviving dimensions in an archaeologically important but badly-preserved animal: 

Campbell, G.E. (2013): Size prediction in archaeomalacology: the Common Mussel, Mytilus edulis L., as an example.  Archaeological and Anthropological Sciences. doi: 10.1007/s12520-013-0155-2

The technique incorporates the most common form of allometric growth, it uses standard statistical software, and it weeds out the dimensions that are not good predictors, leaving the ones that are. It does deal with a marine shell, and it is rude to recommend one’s own paper, but I feel the technique should be applied more widely, or at least debated by the wider zooarch community.

I look forward to your comments.

Greg Campbell

The Naïve Chemist

PS: despite my previous rants about lack of open-access, the editors at AAS did work hard to produce the paper, and therefore I will not be handing out free .pdf copies, at least not until a decent interval has passed.