Understanding speech has become more comprehensible with MRI studies on human brains and equivalent examinations on rhesus monkeys. The pathways, moving from lower to higher functions, have now been partially mapped. Two pathways are identified as involved in the complex analysis of sounds and their subsequent interpretation into speech. The pathways follow a similar journey to sight.
The study also casts some doubt on the unique nature of speech in humans:
What is so interesting to Rauschecker is that although speech and language are considered to be uniquely human abilities, the emerging picture of brain processing of language suggests "in evolution, language must have emerged from neural mechanisms at least partially available in animals," he says.
"Speech, or the early process of language, is well modeled by animal communication systems, and these studies now demonstrate that primate auditory cortex, across species, displays the same patterns of hierarchical structure, topographic mapping, and streams of functional processing," Rauschecker says. "There appears to be a conservation of certain processing pathways through evolution in humans and nonhuman primates."
A familiar story: nature conserves and builds upon what is already in situ.