On Friday I gave you this object to identify:
The idea was to provide a sense of how tricky it can be to identify bits of postcranial bone, even fairly characteristic bits like the humerus (which is what this is).
There were various suggestions, with sheep, goat and deer all getting a mention, but henstridgesj and Jake both got the same identification as the collector when they suggested Domestic Pig Sus scrofa domesticus Erxleben, 1777.
Now you may wonder why I’m being slightly circumspect about whether that answer is actually correct – so I will give you my thoughts.
Erith Marshes are (rapidly becoming ‘were’) an area of grazing land by the Thames on the East side of London. Various domestic animals would have been reared there, so a variety of options present themselves.
Narrowing it down can be done by looking at size and shape. In respect to this Jake said:
This one is 17cm. I have a 8 month old red deer hind humerus which is about 20cm, so it is too [small] to be red but the proportions are right. I have a young roe deer one which is about 16cm but roe is much thinner. So I am going to stick with deer but say axis or sika.
This is useful, because it introduces the idea of robustness of the bone as well as the length. This bone is too short for a Red Deer, but too robust to be Roe Deer. Other options might indeed be Sika or Axis, but given the locality that seems unlikley. So what other options are there?
Sheep, Goats and Pigs are all in the right size range and given the nature of the Erith Marshes they may all have been present in the late 1950’s. To distinguish which we have here then falls to morphology – which is somewhat hampered by the fact that bits of this bone have been damaged.
UCL Boneview provides us with a helpful resource here:
From this image it looks like the most similar bone is in fact the Ovis/Capra (Sheep/Goat) humerus, although it looks relatively longer and thinner than the mystery object. The Sus (Pig) humerus looks far more robust, with a much larger area for muscle attachment.
This robustness in the pig is a bit of a problem for identification, because pigs vary in body mass considerably depending on the breed and how the Pig is reared. This means that the amount of force being transferred through the bones of each individual Pig will vary a lot – which will influence how robust the bone becomes.
Of course the same can be said for Sheep and Goats, although their body mass doesn’t vary anywhere near as much as that of Pigs, so unless the bone from Erith is from a very chunky and squat Sheep it probably is from a lightweight Pig. I’m still not 100% certain which it is, but I think the Pig is a little bit more likely.
Such uncertainties are most unsatisfying, but they are all too common and it’s better to acknowledge them than labour under unfounded certainty.