H/t Alison
When Carrier and Morgan's recent paper on "fisticuffs among robust Australopithecines" crossed our desks at Riddled Research Laboratory, our first thought was to wonder how much fans of the pugilistic art would be willing to pay, to travel back in time to the Pliocene Era and 
It is also possible that Carrier and Morgan are mistaken, and instead of Australopithecines trading punches in strict accordance with Marquess-of-Queensberry Rules, they preferred the humble headbutt, accompanied by Glaswegian-accented hooting. This would seriously disappoint the paying customers.
Below: Homo erectus, no fan of hand-to-hand
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Our second thought was that Carriers & Morgan's central thesis -- that hominin facial architecture evolved as an adaptation to the selective pressures of fist-fighting, with more bone and muscle than can otherwise be explained -- lends itself to an empirical test... i.e. inveigling
Of course we had forgotten the basic principle of architecture (as depicted in any number of horror movies)... Upon encountering a massively over-constructed defensive bunker or citadel, the key question is always not"What were they trying to keep out?", but "What were they trying to keep in?"¹
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But we have finished cleaning up the mess and now would be a good time to draw a discrete veil over the whole proceedings.
Carrier and Morgan argue roughly as follows:
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(1). People hit each other a lot and often break their features in consequence.(2). Robust Australopith species had more muscle and bone in their faces than diet alone could explain, leaving only the 'padding against fists' Just-So story.
(3). Other species of Australopithecus were more gracile, without the extra muscle and bone; this also proves the pugilism account.
(4). "Gracile" is a lovely word for which everyday life provides too few opportunities to use.
(5). Modern Homo sapiens have quite fragile faces, easily fractured; this is an evolutionary response to the reduced rate of fisticuffs in the Homo lineage,
"Perhaps," Another Kiwi vouchsafed, "at some point our ancestors lost access to their supply of Tree-of-Life, depriving us of the virus DNA which we need to complete the transformation to the better-designed physiognomy of Protector status."
"Somehow the authors have neglected the corollary," said tigris, "that the human buttocks are as upholstered as they are with muscle and fat as an adaptation to the selective pressure of people sneaking up behind us and kicking our butts."²
I did not answer, for I was beating my head against the desk by this point. Fortunately the architecture of the human face is an adaptation to the evolutionary pressure of being beaten against desks, and no lasting damage was inflicted.
One further possibility must be mentioned; which is that early hominins played games of chess as their preferred arena for contests of social dominance. Here Bookstein illustrates how biorthogonal-transformation chessboards can map the game-play favoured by Proconsul,³ Homo erectus and Australopithecus onto more contemporary strategy. Or they're an extension of D'Arcy Thompson's approach to allometry, from 1977 because that is we roll.
Image may be NSFW.
Clik here to view.
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1 Left-hand art swiped from Joachim Boaz's site, which you should be visiting, if you are not already doing so.
2 Evolution leaves no stern untoned.
3Image may be NSFW.
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