This weeks top rated post is “humans have giant chimp brains” with a grand total of 3 up-votes, making it the 3rd most popular post of all time. As such this weeks Supplementary Sunday seeks to expand on this well-liked topic by identifying yet another similarity between the human and chimp brain: Wernicke’s area.
This is a particularly famous section of the brain so apologies if you’ve heard this summary before. It’s a small region found in the left hemisphere of the brain and was first identified in the 19th century by Dr Wernicke (as the name indicates) who noted a link between brain damage to that part of the brain and an inability/impairment to comprehend language.
Based on this link it was claimed to be the region of the brain responsible for language comprehension, however this view has now evolved somewhat. Language comprehension is now understood to be more dispersed throughout the left side of the brain with Wernicke’s area being an “epicentre” of this ability, rather than the sole location it occurs.
As such it isn’t quite as important as once believed but still very crucial. This has obviously prompted several studies trying to find an analogues area in chimps and other great apes. Surprisingly (given their lack of vocal language) the area of the chimp brain which should be the Wernicke’s area is assymetrical, like in humans. In other words, that region of the brain is larger in both humans and chimps on the left side.
Broca’s area is another assymetrical feature in the human brain associated with language, again being larger on the left than the right. Rather than language comprehension this region is linked to language production, with it being first discovered (again) by identifying damage to this area in patients unable to speak. Once again, it is now believe to be just one part of this process and, again, this assymetry is also seen in ape brain.
All of this suggests that the foundation for our brain structure – even parts associated with seemingly unique human abilites – was already laid in our ape ancestors
|Cantalupo, Claudio, and William D. Hopkins. 2001. ‘Asymmetric Broca’s Area in Great Apes’. Nature 414(6863): 505–505. doi:10.1038/35107134.|
|Gannon, Patrick J., Ralph L. Holloway, Douglas C. Broadfield, and Allen R. Braun. 1998. ‘Asymmetry of Chimpanzee Planum Temporale: Humanlike Pattern of Wernicke’s Brain Language Area Homolog’. Science 279(5348): 220–222. doi:10.1126/science.279.5348.220.|
Apologies for the short post. I would try and claim I’m trying a new format but in reality I’m just being distracted by the Wimbledon final. However, if you like this abridged version speak up. Suggestions are always welcome.