MONKEY BRAINS: Could the monkey skull hold the key to the evolutionary origin of language processing?
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The use of vocalizations, such as grunts, songs or barks, is extremely common throughout the animal kingdom. Nevertheless, humans are the only species in which these vocalizations have attained the sophistication and communicative effectiveness of speech. How did our ancestors become the only speaking animals, some tens of thousands of years ago? Did this change happen abruptly, involving the sudden appearance of a new cerebral region or pattern of cerebral connections? Or did it happen through a more gradual evolutionary process, in which brain structures already present to some extent in other animals were put to a different and more complex use in the human brain?
A recent study in Nature Neuroscience yields critical new information, uncovering what could constitute the “missing link” between the brain of vocalizing nonhuman species and the human brain: evidence that a cerebral region specialized for processing voice, known to exist in the human brain, has a counterpart in the brain of rhesus macaques.
Neuroscientist Christopher I. Petkov of the Max Planck Institute for Biological Cybernetics in Tübingen, Germany, and his colleagues used functional magnetic resonance imaging to explore the macaque brain. They measured cerebral activity of awake monkeys that were listening to different categories of natural sounds, including macaque vocalizations. The researchers found evidence for a “voice area” in the auditory cortex of these macaques: a discrete region of the anterior temporal lobe in which activity was greater for macaque vocalizations than for other sound categories.
This region was observed in several individuals, even under the condition of total anesthesia. More surprising, the region showed repetition-induced reduction of activity—or neuronal adaptation—in response to different calls coming from the same individual. This finding suggests that this brain region processes information about the identity of the speaker, a phenomenon that is also observed in the human voice area.
Long History of Voice?
Perhaps the most remarkable implication of these findings is that the voice area previously identified in the human brain is not uniquely human and that it has a counterpart in the brain of nonhuman primates. That discovery, in turn, implies that the voice area has a long evolutionary history and was probably already present in the common ancestor of macaques and humans some 20 million years ago. It is known that the cognitive talents underlying voice perception, such as speaker recognition, are shared with many other animal species, but the findings of Petkov and his colleagues provide a cerebral location for these abilities.
Ironically, most of the research into the evolutionary basis of language has focused so far on a single function—speech perception—which is unique to humans, and thus evolutionary precursors are hard, if not impossible, to identify. The present findings hint at another, possibly more rewarding, strategy: perhaps looking at what we have in common with other animals—that is, a rich cerebral substrate to process vocalizations and extract speaker-related information—will allow us to understand the evolution of speech. Indeed, Petkov’s findings indicate that when our ancestors began to talk, they already were equipped with sophisticated neural machinery specialized in voice processing.
Another important implication of Petkov’s findings concerns the functional lateralization of the macaque voice area. A well-established property of the human cerebral substrate for speech (particularly speech production) is its lateralization to the left hemisphere. This known asymmetry has led researchers to investigate whether a similar left-hemispheric bias could be found in other animals, as a possible evolutionary precursor of human language. Unfortunately, this long-standing belief has possibly resulted in a strong bias in the literature, whereby studies uncovering any leftward asymmetry in nonhuman primates are much more likely to be published in leading journals.
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9 Comments
Add CommentGreat resarch !!
Reply | Report Abuse | Link to thisI've been hopeing that we humanbeing could talk to other species such as monkey some day.
Amazing! Exciting! :)
Reply | Report Abuse | Link to thisWhat about dolphins? Do they not have a fairly sophisticated language?
Reply | Report Abuse | Link to thisVery interesting research. Perhaps this will do for the innate hardwired language approach what diachronic philology did for synchronic studies of language. Provided a historical and empirical foundation based on rigorous criteria of development that in a roundabout fashion led back to more thoroughly generalizable cross-sectional work.
Reply | Report Abuse | Link to thisThe interplay of discrete areas of the brain, and the synergetic structures they spawn may even lead to statistical correlations that can be empirically validated and give us a basis for quantifying the degrees of variance possible between different languages and different aspects of their development in relation to dialectal change, sound shifts, agglutination, morpheme discreteness, structural persistence of grammatical forms versus deeper syntactic relations, and even semantic developments perhaps.
Establishing a scale in the evolution of vocalization would give us a set of nodes we can study to trace a scientific line of growing communicative effectiveness until we reach the communicative leap involved in human speech and its interaction with social needs and desires and representations. A similar process in synchronic linguistics can be seen in the development of continuums and nodes to deal with the dialectal relations in communities using both creole and standard variants (of say English in Jamaica, or in south-eastern coastal parts of the US).
This would give us a cross-species web of "language" or "quasi-language" complexities open to productive cross-disciplinary investigation.
This may prove to be a small acorn planted in surprisingly fertile soil!
Pass the bananas.
Reply | Report Abuse | Link to thisRE: Cochlea defines “voice area” in our brain (monkey or human)!
Reply | Report Abuse | Link to thisDear Jonah Lehrer, Editor, Mind Matters:
Despite the nice review of the above work on the macaque brain by neuroscientist Chris Petkov, et al, at the Max Planck Institute, the questions posted by Pascal Belin were not at all critical, nor in line with the current advanced hearing or voice physiology: For example,
1] Does the voice area represent a hardwired preference for the particular acoustical structure of vocalizations from one’s own species?
[Yes, the “voice area” is anatomically and physiologically hardwired to the (evolutionally) well-defined “acoustical structure” of the “spiral cochlea” in the ear of each species (human or macaque) -- please see my seminal book “Gods, Genes, Conscience” Chapter 11.3 The Auditory and Vocal Circuitry (listed below).]
2] Or is it more simply a “formant” detector, a structure specialized in detecting vocal features in general?
[Yes, the “formant” detector is one neural circuitry that begins with the hair cells in the spiral cochlea, which electromechanically and selectively receive, transmit, and present “voice frequencies” to the “voice area” of our brain for interpretation and memory modulation -- as explained in 1] above; and also please see Chapter 15.4 Memory Modulation and Recall: A New Hypothesis of Psychic Imagery, Perceptivity, Creativity, and Reflectivity (including voices or hearing mechanism).] And last, but not least (to be continued in Part 2),
RE: Cochlea defines “voice area” in our brain (monkey or human)!
Reply | Report Abuse | Link to thisDear Jonah Lehrer, Editor, Mind Matters (Part 2):
3] Another possibility is that this voice area is actually a “social” structure, tuned to vocalizations because they are cues for social interaction and not because they share a particular acoustical structure.
[No; in my latest theory of mind or “Memophorescenicity,” the quantum mechanics of memory is that all of our auditory sensory (including visual, tactile, taste, etc) and vocal circuitries are interconnected within our brain; and closely associated (or modulated) in our memory formation and recall, including “social” identification and interaction, all those imagery recognitions that are all fundamental (or accustomed to) cues for the group survival of “social” animals, such as humans or macaques -- please see “Gods, Genes, Conscience” Chapter 15 The Universal Theory of Mind.]
Meanwhile I thought Belin, et al’s 2004 review of “Thinking the voice: Neural correlates of voice perception” is exemplary -- please see it here: http://www.psy.gla.ac.uk/docs/download.php?type=PUBLS&id=706.
Best wishes, Mong 9/13/8usct11:19a -- author-philosopher “Gods, Genes, Conscience” (iUniverse, 2006); “Decoding Scientism” and “On Consciousness” (works in progress since July 2007).
RE: Cochlea defines “voice area” in our brain (monkey or human)!
Reply | Report Abuse | Link to thisDear Jonah Lehrer, Editor, Mind Matters (Part 2):
3] Another possibility is that this voice area is actually a “social” structure, tuned to vocalizations because they are cues for social interaction and not because they share a particular acoustical structure.
[No; in my latest theory of mind or “Memophorescenicity,” the quantum mechanics of memory is that all of our auditory sensory (including visual, tactile, taste, etc) and vocal circuitries are interconnected within our brain; and closely associated (or modulated) in our memory formation and recall, including “social” identification and interaction, all those imagery recognitions that are all fundamental (or accustomed to) cues for the group survival of “social” animals, such as humans or macaques -- please see “Gods, Genes, Conscience” Chapter 15 The Universal Theory of Mind.]
Meanwhile I thought Belin, et al’s 2004 review of “Thinking the voice: Neural correlates of voice perception” is exemplary -- please see it here: http://www.psy.gla.ac.uk/docs/download.php?type=PUBLS&id=706.
Best wishes, Mong 9/13/8usct11:22a -- author-philosopher “Gods, Genes, Conscience” (iUniverse, 2006); “Decoding Scientism” and “On Consciousness” (works in progress since July 2007).
@ tictacrew We can talk to other species, I talk to my dog & cat all the time. If I spent any amount of time with a monkey, I could talk to them, people all over the world talk to other species everyday, Its just that they"re all very limited in what they have to say or think. Its only us humans that think in abstract patterns, & communicate abstract thoughts.
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