Man’s jaw evolved to take punches

London: Wonder how our ancestors evolved beefy facial features? According to a new theory, defence against fist fights seems to be the answer.

The bones most commonly broken in human punch-ups also gained the most strength in early “hominin” evolution. They are also the bones that show most divergence between males and females.

The paper, in the journal Biological Reviews, argues that the reinforcements evolved amid fighting over females and resources. Thus, violence drove key evolutionary changes.

Fossil records show the australopiths, immediate predecessors of the human genus Homo, had strikingly robust facial structures.

For many years, this extra strength was seen as an adaptation to a tough diet. But more recent findings, examining the wear pattern and carbon isotopes in australopith teeth, have cast some doubt on this “feeding hypothesis”.

Instead, Prof. David Carrier, the theory’s lead author, and his co-author, physician Dr Michael Morgan, propose that violent competition demanded the development of these facial fortifications — called the “protective buttressing hypothesis”.

The strong brow ridges, cheek bones and jaw of early hominins may have evolved as a defence against the fists of other males.