346 — Reevaluation of ‘endocostal ossifications’ on the Kebara 2 Neanderthal ribs

García-Martínez et al (10.1016/j.jhevol.2018.04.011)

Read on 01 August 2018
#neanderthal  #evolution  #humans  #homo-sapiens  #ribs  #intercostals  #bird  #Hox  #gorilla  #primate  #ribcage  #disease  #paleolithic  #paleoanthropology  #anthropology  #bird  #ossification 

The Kebara 2 specimen is an exceptionally well preserved Neanderthal skeleton found on Mount Carmel in Israel. K2 most likely lived 60 thousand years ago and was discovered again in 1983. Because he is so well-preserved, K2 is commonly used for paleoanthropological study: In particular, K2’s hyoid bone was once used to substantiate the claim that Neanderthals were capable of complex speech.

But there is something strange going on with K2’s ribs: Ribs 5, 6, and 7 (and perhaps 8) on the right side show signs of unnatural ossification. That is, there are bony growths on these ribs that suggest disease of the subcostal or intercostal muscles.

This isn’t so strange by itself: Plenty of remains exhibit some sort of disease or another. But what makes this case so strange is that the ossifications seen in K2 aren’t seen in any other human skeletal repositories; the only case of primate endocostal ossification is in a gorilla specimen (though it’s very common in other species, including many types of bird).

For a while, this was considered to be a big red flag when using K2 to understand Neanderthals and human evolution in general, since if K2 had been sick or otherwise unusual, it’s not a good representation of the Neanderthal archetype.

This research confirms that this is not the case: K2’s endocostal ossification is abnormal for modern humans, but was probably a simple genetic disorder that didn’t affect the individual’s life in any meaningful way. In other words, K2 is as useful as ever for understanding the anatomy and evolution of Neanderthals.