Re: Sexual preferences along the generatios: Change of fashion or evolution?

Gaby,
Thanks for the intriguing question. In answer I would first like to say that, from a biological perspective, there are only a few physical traits that nearly all humans find universally attractive: Youth, a clear unblemished skin and very symmetrical faces and bodies.

Aside from these traits, just about any attribute can be found attractive by a person or a society. You noted a difference between the body types and beauty standards of "ancient sculpture and drawings" with those that exist in many (often western) cultures today. These variations of beauty standards are decided by what a culture (or artist) finds attractive. Many early societies created "fertility figures" like the Venus of Willendorf, which were sculptures of often very fat women. Hellenistic and Renaissance art is often rife with women of a larger body type than one would see in a typical fashion magazine today.

These societies, as well as many others, value heavy-set women for a variety of reasons: A good store of body fat means plenty of food for a developing embryo, but more poigniantly, an excess of body fat means that one has access to more resources than they need to survive, so being heavy is a sign of high social and or economic status in these cultures. By comparison, having the time and money to workout at a gym could also be a sign of social status in many modern cultures.

Both "skinny" and "fat" body types have their advantages in different physical and social environments, so you find different beauty standards across land and populations. For instance, I had a proffessor in college once tell me that she had a Kenyan student in one of her classes who was showing her some pictures he was going to take back to his family. Many of the pictures were of women that by western standards would be considered quite obese. The Kenyan student found them to be extremely attractive.

In contrast, in the United States, eating disorders are very common among women, especially teenagers. These disorders are clearly not evolutionarily advantageous because they hinder pregnancy and the health of embryos and can even lead to death.

In short, many aspects of beauty, including weight, are determined culturally. Culture is our means of quick adaptation within our lifetime and is often an extension or possibly a contradiction of what might be evolutionarily advantageous.

The second part of your question, about mate selection by the parents, is also a cultural mechanism. As you say, it is often done to maintain or elevate the economic and/or social status of a family by linking the family, through marriage, to a family of the same or higher status, and similar cultural values. It is justifiable in evolutionary terms by the fact that the more prosperous you are the generally more successful, biologically, the individual will be.

I hope I answered your question. For more information, I recommend Desmond Morris' book, "The Naked Ape".