Yesterday’s email from Earthsky.org contained links to good summaries of a series of papers recently published about the genetic similarities underlying bird song learning and human language. The science reported here is of an unprecedented scale as many researchers in many universities analyzed the genome of over 40 bird species thereby providing a comprehensive map of the evolution of various bird species and which genes contributed most to song learning. Then these results were compared to analyses of the human genome’s contribution to speech. These studies required new computational algorithms run on super-computers because of the size of the data set. Wow! And wouldn’t you know it, we share many of the same genes that control vocal performance. Here are some links:
So I am thinking back to 2 earlier posts in June, 2014, on the biological roots of language that discussed how two evolutionary streams from birds for the melody and silver gibbons for the words may have contributed to the confluence resulting in human language.
As reported in the last link above from the National Science Foundation, modern birds appeared around 66 million years ago after a meteor strike eliminated dinosaurs and much other life. Birds came through that holocaust and then underwent an evolutionary explosion into the many forms around today. Mammals also came through that holocaust; their evolution has been less explosive perhaps but seems more extensive and progressive when thinking in terms of brain complexity. Primates have been around almost as long. Less is known about the evolution of gibbons but they seem to have appeared in current form somewhere around or before 8 million years ago. Homo sapiens or our ancestral species appeared only around 500,000 to 200,000 years ago. So these genes we have in common with birds have been around, replicating themselves over and over and over again, a very long time. What has changed, then, I guess, would be their context, the genes surrounding them, and these presumably led to increased empathic capabilities and to symbolization.
Some of the best song learners, vocal mimics, are parrots and they have been found now to have evolved with particularly powerful song learning ability. They are monogamous and some mate for life. Oddly (perhaps), gibbons share these features. At the least this suggests that the evolved genetic context for vocalization genes supported more stable social relationships and with mammals this led to increased empathic capacities. I think this suggests something else as well. In his book, The Selfish Gene, Richard Dawkins floats the suggestion that some species, because of their particular genome, are more evolvable than others. In learning about these recent studies I was struck by how birds have diversified over the past 66 million years into several thousand of species but they do not seem to have developed any great new abilities. Mammals have also diversified (and let’s not bring insects into this) and they have developed the prerequisites for greatly increased cognitive and social organization. Do mammals, especially the lines leading to cetacea and primates including hominids, have greater evolvability than birds? Looks like it, and I cannot resist this speculation. As I mentioned in the June, 2014, posts, birds and mammals have different embryological development. All bird embryos start out as male and some are feminized through hormonal production. All mammal embryos start out as female and some are masculinized through hormonal production. Is starting female associated with more evolvability and starting male more limiting? That might be a new twist in gender inequality, eh?