Bengalese Finches And An Hypothesis On Language Origins

Recent research has found that "evolution and [the] development of language are ... inherently related," an observation that is backed up by the theory of evolutionary developmental biology (Oller 1).  This theory "emphasizes the idea that no structure or capability can be evolved without being developed, and that consequently the targets of natural selection are often, if not usually, developmental processes or systems" (Oller 1).  That is, a species cannot evolve if there is no developmental growth, which occurs through the process of natural selection.    

As the origin of the development of language is still a mystery, scientists believe they may have come across a potential possibility, an hypothesis that is based off of observations of Bengalese finches. 

Bengalese finches are known to be friendly and sing beautiful, complex melodies.  These characteristics juxtapose its ancestor, the white-rumped munia, as munias are aggressive and whistle “a scratchy, off-kilter tune” (Erard). 

                                                        Figure 1:  White-rumped munia             

Figure 2:  Bengalese finch

This turnabout in behavior sparked the self-domestication hypothesis.  This hypothesis states that “skills such as learning complex calls, combining vocalizations, and simply knowing when another creature wants to communicate all came about as a consequence of pro-social traits like kindness” (Erard).  In connection to human evolution, scientists postulate that “the building blocks of language are a byproduct of brain alterations that arose when natural selection favored cooperation among early humans” (Erard).  According to Charles Darwin, this desire for cooperation over aggression amongst early humans’ social interactions led to not only behavioral changes, that humans “essentially domesticated themselves,” but also evolutionary changes, specifically “lower levels of circulating androgens (such as testosterone) that tend to promote aggression” (Erard).  As testosterone decreased, neurohormones, including serotonin, increased and aided in humans’ abilities to “infer others' mental states, learn through joint attention, and even link objects and labels—all prerequisites for language” (Erard). 

Focusing back, ornithologist Kazuo Okanoya, from the Riken Center for Brain Science in Wako, Japan, did an intensive quantitative study on the relationship between Bengalese finches and white-rumped munias to language.  According to Okanoya, while both birds are vocal learners, munia “songs tend to be shorter, simpler, and full of unmelodic segments of acoustic "noise," compared with the longer, louder finch songs, which contain peeps, chirps, and segments that often repeat and recombine in improvisational ways” (Erard).  He proposes that this change occurred behaviorally, as the finches were being domesticated and living in a “relatively stress-free environment,” as well as biologically, as tests show that “finches have lower fecal levels of corticosterone —a hormone that boosts aggressiveness and blunts cognitive functioning in birds;” high levels of corticosterone “inhibit the growth of neurons in the birds' song-learning system, which is larger in the finches than in the munia” (Erard).  Furthermore, the language/song abilities of finches forwarded natural selection through mating:  Okanoya suggests that, “because attention-getting songs help advertise fitness to females, the males best at learning and singing would be most likely to pass their genes on to the next generation” (Erard).  In association to the finches, evolutionary linguist Simon Kirby speculates that if “early humans somehow developed their own lower-stress "domesticated" environment—perhaps as a result of easier access to food—it could have fostered more cooperation and reduced aggression” (Erard). 

Bibliography

Bengalese Finch . EFinch, www.efinch.com/species/society.htm.

Erard and Matacic. “Can these birds explain how language first evolved?” Science, August 2,

2018. http://www.sciencemag.org/news/2018/08/can-these-birds-explain-how-language-first-evolved.

Oller, Dale, and Griebel. “New Frontiers in Language Evolution and Development:
Introduction to the topiCS Volume.” Top Cogn Sci. 8, no. 2 (April 2016): 353-360. doi:10.1111/tops.12204
“White-Rumped Munia.” The Internet Bird IBC Bird Collection , www.hbw.com/ibc/species/white-rumped-munia-lonchura-striata.