Afarensis is a 3.5-2.8 million year old hominin from the Kada Hadar member of the Hadar formation in the Middle Awash, Ethiopia. He is approximately 41 inches tall, weighs approximately 60 pounds and has a cranial capacity of a whopping 410 cc (approximately). Afarensis is currently considered to be transitional between apes and humans and displays some traits of both. Since he spends a lot of time on the couch watching monster movies, some observers question whether he is an obligate biped (although no one has observed him climbing a tree). He also has a blog called 
This is actually a combination of two posts I wrote on the same subject...
According to Eric Trinkaus we started wearing shoes approximately 30,000 years BP.
(A 26,000 year-old early modern human, Dolni Vestonice 16 from the Czech Republic, showing the reduced strength of the bones of the lesser toes. It is one of three partial foot skeletons from Dolni Vestonice that shows the reduced lesser toe strength, all dating to about 26,000 years ago.[Photo Credit: Erik Trinkaus / Czech Academy of Sciences])
He analyzed the the feet of middle and upper Paleolithic humans and compared the strength of the toes (based on robusticity, size of muscle markings, etc.) with leg strength (I'm assuming this means the tibia and fibula - again based on robusticity, size of muscle markings, etc.). Trinkaus notes that around 30,000 years ago toe strength underwent a reduction while calf strength remained the same. He chalks up this decrease in toe strength to the full time use of supportive footwear:
During barefoot walking, the smaller toes flex for traction, keeping the toe bones strong. Supportive footwear lessens the roll of the little toes, thus weakening them.Trinkaus is certainly one of the more original thinkers in Paleoanthropology, but I am a little bit skeptical. Granted, I haven't read the article in the October Journal of Archaeological Science (abstract available here - so if someone out there with access wants to send me a copy of the article...?). My first thought on reading the Science Daily article was what about allometry and/or sexual dimorphism?
Part Two
Abnormal Interests has linked (Thanks!)to my post on when humans started wearing shoes. He also links to a BBC News story that provides more info than the Science Daily article. As I suggested in the comments to my original article two things needed to be done to make a convincing case. First, a comparison needed to be made between shoe wearing and non-shoe wearing modern humans. From the BBC article:
To test the theory that the more delicate toes resulted from shoe use, the Washington University researcher compared the foot bones of early Native Americans, who regularly went barefoot, and contemporary Alaskan Inuits, who sported heavy sealskin boots.Again, he identified chunkier toes in the population that routinely went without shoes. The research suggests shoe-wearers developed weaker toes simply because of the reduced stresses on them during their lifetime; it was not an evolutionary change.
Second, I was concerned about how this could be passed on to future populations. As the above quote also shows, Trinkaus is not advocating this as an evolutionary change. Adaptation can occur in many different ways. The more permanent types represent changes in the genetics of the population. Another type (from Stini in his book "Ecology and Human Adaptation") occurs in response to stress and may persist for a long period of time and occur in individuals rather than populations. Examples would be moving to a higher altitude or muscular hypertrophy (as a response to high activity levels). It is this second sense that Trinkaus is talking about. Bone has two responses to stress. More bone can be laid down or bone can be absorbed. In the case of muscular hypertrophy, mentioned above, the muscle origins and insertions would become larger in order to accomodate the increased muscle size. Another effect would be that increased muscle size means that increased force can be exerted and bone will be laid down to handle that increased force. In the case of human feet, since humans started wearing shoes, according to Trinkaus, there was a decreased stress on the toes so bone was absorbed leading to more gracile toes. As I mentioned in my first post, there was a trend towards more gracile skeletons from Neanderthals to archaic humans to anatomically modern humans (irregardless of whether you go for Out-of-Africa or Multiregional Continuity - or for that matter one's views of the taxonomy of the above species) so untangling the two is difficult. Having said that, this study certainly turned out to be more interesting than I originally thought.
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