There is an interesting article in HOMO – Journal of Comparative Human Biology on the proximal femur. The article, Geometric morphometric analyses of hominid proximal femora: Taxonomic and phylogenetic considerations, looked at whether one can separate extant hominids into different taxa using geometric morphometrics and whether one could distinguish Homo from Australopithecus and Paranthropus. (more…)
AL 288-1 casts a large shadow. The fact that such a large percentage of Lucy’s skeleton was recovered has overshadowed – at least in the public’s mind – that fact that a wide variety of fossil material was recovered at Hadar.
Bioarchaeologists and paleoanthropologists draw on a wide variety of methods in order to analyze bone. The exact technique depends upon the problem being addressed. One technique, associated mainly with Christopher Ruff, that has been around since the late 1970′s involves the use of beam model analysis. In beam model analysis cross sections of bone, perpendicular to the long axis, are taken and the distribution of bone is analyzed. Based on the measures derived from the analysis the mechanical properties of the bone can be determined, and this in turn can be related to locomotion, changes in subsistence strategy, sexual dimorphism, and various temporal trends (among other things). This post is concerned with the analysis of temporal trends, in particular, with the effects of shoe wearing on pedal morphology.
Before going further, let me remind readers of the purpose behind “What We Can Learn From Bones.” Creationists like to make two main claims about paleoanthropology. First, they claim that all we have are bone fragments and teeth, and by implication, that we can learn nothing from bone fragments and teeth. Second, they claim that paleoanthropology is a historic science and since humans were not around to witness the events in question we can never really learn anything about the past. The point of “What We Can Learn From Bones” is to show that we can gain a lot of useful knowledge from bone fragments and that there are a number of sophisticated methodologies that allow us to test our inferences about the past. Previous posts in “What We Can Learn From Bones” can be found by scrolling down my sidebar and clicking on the “Bone Fragments” category.
I am also departing, somewhat, from the outline I mentioned in the first part of “Paleodiets, Early Hominins, and Mole Rats” mainly because of several recent papers that are relevant to the issue (which I will get to later).
I have been fighting with the idea for this post for the last couple of weeks ever since I read this paper on the human amylase gene. Part of the reason for the delay in writing about the amylase paper is that I have come down with what I suspect is lateral epicondylitis and typing seems to aggravate it. Worse yet, the more I thought about the subject the longer and more complicated the post became. At this point I have decided to break it into a series of posts.
Kambiz has already done a good job of dissecting some of the claims made concerning this story about recent research on bipedalism so this post is kind of redundant. Having said that, I have a few things to say on the subject as well. Let’s start at the beginning.
As I mentioned in the previous post in this series, Semicircular canals are fully formed by about age two. This makes them an interesting and useful object to study, but in depth studies did not become common until the creation of CT scanners. Previous techniques were highly invasive and destructive. Starting in the mid 1990′s and continuing to the present, Fred Spoor embarked on an ambitious program studying mammalian semicircular canals. Primates and hominins were a special focus of this research. As we shall see below, several other researchers performed studies of the semicircular canals as well.
So, what are semicircular canals? To begin with, they are not actually bone. They are membranes. Technically when paleoanthropologists study semicircular canals they are looking at the bony labyrinth – that is the bone surrounding the membranes. In short, considering this part of my “what you can learn from bone fragments” series is somewhat misleading.
George Gaylord Simpson is probably responsible. I say that because in his influential The principles of classification and a classification of mammals he has this to say about whales: