Understanding the evolution of language requires evidence regarding origins and processes that led to change. In the last 40 years, there has been an explosion of research on this problem as well as a sense that considerable progress has been made. We argue instead that the richness of ideas is accompanied by a poverty of evidence, with essentially no explanation of how and why our linguistic computations and representations evolved. We show that, to date, 1) studies of nonhuman animals provide virtually no relevant parallels to human linguistic communication, and none to the underlying biological capacity; 2) the fossil and archaeological evidence does not inform our understanding of the computations and representations of our earliest ancestors, leaving details of origins and selective pressure unresolved; 3) our understanding of the genetics of language is so impoverished that there is little hope of connecting genes to linguistic processes any time soon; 4) all modeling attempts have made unfounded assumptions, and have provided no empirical tests, thus leaving any insights into language’s origins unverifiable. Based on the current state of evidence, we submit that the most fundamental questions about the origins and evolution of our linguistic capacity remain as mysterious as ever, with considerable uncertainty about the discovery of either relevant or conclusive evidence that can adjudicate among the many open hypotheses.
This seems like a statement of confusion. The story of language evolution is primarily a story of cultural evolution. Languages evolved by adapting themselves to the human mind and human physiology. Expects should be looking primarily to memetics - not genetics - for their understanding of this topic. Human genes will have changed in response to the culture - but the usual story with cultural evolution is that the memes race on ahead and host genes are dragged along behind. We do, in fact, know quite a lot about how languages evolve - since we can see them doing it in real time, from pidgins through creoles to mature languages.
The paper starts out by saying:
In this paper, we are interested in biological as opposed to cultural evolution.
Alas, that's simply not a permissible move when studying language evolution. Memes and genes coevolve, with the memes leading and the genes following. If you don't start from there, you've dismissed all the correct solutions to this issue. Also, cultural evolution is biological. No wonder these experts appear to be confused: they are doing things all wrong.
H/T to Replicated Typo for this one.