Lip movements. Cheek changes. Eyebrow raises. Teeth showing. All of these actions are subtle ways that both humans and primates subtly communicate with each other. Simple muscle movements in the face result in the ability of conveying a message. One question that researchers have been studying is whether human and primate emotional signaling have the same form and function. This information is key in understanding the evolutionary specializations for each species. Though this data is proves very beneficial, it is very hard to measure objectively. Not very many tools have been developed to handle such research procedures. However, recently scientists, Parr, Waller, and Vick, have reconfigured a tool used on humans for many years and have now applied it to chimpanzees. This research tool is based on anatomical facial movements due to muscles. Through using this tool researchers have found that humans and primates share many homologous facial movements, implying similar perceptual and emotional communication techniques. These conclusions are based on testing done on chimpanzees that evaluate if they are capable of separating an emotional facial image from a neutral one. In this study seven main model faces were used: pan hoot, barred teeth, pout, alert face, stretch-pout whimper, scream, and relaxed open mouth face. The only one that proved difficult to indentify was the relaxed-open mouth due to its lack to an emotional tie. It is clear that evolutionary pressure have forced species to begin to rely on nonverbal communication. The question is what were the selective pressures that encourage such a mechanism?
March 9, 2008 at 4:38 pm
Hmmm. It would seem as if non-verbal communication would have come before verbal communication–or, at least, that’s the general view of evolutionary biologists, isn’t it? So your second-to-last sentence is a bit misleading. The pressures, then, with regard to language formation, would presumably have acted upon the already extant facility for recognizing, from external cues, another creature’s internal state (or emotion). Or, perhaps, since a good deal was already being communicated by physical cues–not only facial, but also postural–could language have evolved on some parallel track? Maybe simply on physical bases, like throat and glottal configuration?
March 12, 2008 at 5:16 am
Wow… I would love to take part in this type or research. Evolution has interested me since I was a little girl. Before I ever took a biology class or knew anything about evolution, i would ask my mom why apes and humans are similar. It is funny that there are still people that do not believe in evolution. The evidence out there makes it so obvious and studies like this are so fascinating!
March 18, 2008 at 5:14 am
This is an interesting post. I took psychology last semester and one thing we learned last semester was that humans are very good at recognizing faces. Even young children show different reactions to faces than other stimuli. I wonder if chimpanzees react in a similar manner. I know it would be very hard for me to tell chimpanzees apart but I assume that chimpanzees would do a much better job of recognizing members of their species. I think this must have an emotional tie as well. The last sentence did throw me off because I think non-verbal communication is very primal. What could it have evolved from? Also, during biology lab we discussed the shared derived characteristics between chimpanzees and humans (basically what sets us apart from primates). Prehensile feet and hands and verbal communication are two examples of the very few things that set us apart from chimps!