Sunday, January 17, 2010

The biology of dance

Most (all?) human cultures around the world include dancing of some form. People like to dance -- like to "shake those tail-feathers" to show off for the group and, most particularly, to show off to members of the opposite sex (usually).

But the different cultures around the world, i.e. different human populations, dance differently. They have different styles, different techniques, different rhythms and music (or not). Why the different cultures of dance?

Culture, obviously, does not exist in a vacuum. People incorporate elements of their local environments into their culture. Both Papuans and Austrians decorate themselves with bird feathers, but Papuans use feathers from birds of paradise while Austrians use those of the grouse. Human populations also borrow cultural elements from other groups -- extensively.

Other animals besides humans also have cultures (learned behaviors). Some chimpanzees make tools to fish out termites from termite mounds. Macaques in parts of Japan warm themselves in hot springs in the winter-time. However, these are learned behaviors that are within the capabilities of these animals. Neither species is going to build skyscrapers or drive around in cars any time soon because those behaviors are not within their capabilities. Such activities are not in their nature.

Human cultures are also products of biology. I suggest that human populations produce cultures based in part on their temperaments and personalities and levels of intelligence. Just like the chimps and macaques, people do those things that they are capable of.

Dance is an interesting example. Here are three examples of dance from three different cultures >> traditional dances from Dakar and Senegal in West Africa; a traditional Legong Keraton from Bali; and a Slovakian "throwing dance" (personally, I really like this throwing dance, but unfortunately it's not embeddable):







Now, there are a lot of differences between these three styles of dance and, no doubt, uncountable environmental and biological reasons have contributed to these differences. I would like to focus on just one element of these dances that differs and that is the level of energetic movements in them; in particular the characteristics of the movements and the body parts that are engaged in those movements.

The most reserved, controlled of the three dances is clearly the Balinese dance. The movements are extremely precise and, although obviously it takes a lot of energy to keep one's movements under such control, the movements themselves are not very energetic, comparatively speaking. Interestingly, the dancer's torso remains very stable and is not gyrated very much at all.

Same goes for the Slovakian dancers -- not much movement of the upper body. Of course it takes a lot of energy and power on the part of the male dancers to throw their partners around, and the female dancers are also expending energy in their jumps, but on the whole the dancing is quiet staid. Less so than the Balinese dancer, but much more so than the West Africans.

The traditional West African dances are the most energetic, at least in how the moves appear; and the muscles in the dancers' upper bodies are very much engaged in all sorts of movement, not simply in maintaining a good posture (as in the case of the Balinese dancer). The dances are speedy and full of energy!

I can think of several biological factors that might be contributing to the differences between the dances; but the one I'd like to mention now is the genetic variation that has been connected to sprinting: the ACTN3 gene.

From Genetic Future:
The ACTN3 gene encodes a protein called α-actinin-3 ... which is found within the fast fibres of muscle - the cells that are required for generating rapid, forceful contraction in activities such as sprinting and weightlifting.... [My emphasis.]

[O]ver the last five years we and other groups have assembled evidence suggesting that it does influence how good your muscle is at generating explosive power. We first showed in 2003 that X/X individuals are significantly under-represented among elite Australian sprint/power athletes, suggesting that the absence of α-actinin-3 in X/X individuals is detrimental to optimal muscle power generation. This association has since been replicated in four separate athlete studies by groups in Europe and the US....
Now, 70% of Jamaicans (whose ancestors came from West Africa) have the variation of the gene that makes for "rapid, forceful contraction in activities." Only 30% of Australians (presumably a majority with European ancestors) have it. I don't know what sort of frequencies are found in Asians.

I would not be surprised at all if this biological difference between these human populations contributes to many differences between the various cultures of these groups, not the least of which is the physical activitiy known as dance.

Look at these dancers from Guinea. Fast twitch muscles must be at play here!:



People do what comes naturally to them.

Happy Sunday, all!