Someone writes: Susan Stockwell <[log in to unmask]> Subject: dentists >his teeth would have enough room in the jaw (a great rarity in my > >generation and younger) because the jaw would have developed properly > >through suckling. European populations, especially north and western European populations, from which many "white" Americans are descended, tend to have small faces, tucked under their skulls, as do many Asian populations. In contrast, many Eastern European, African, and Australian Aborigine populations have big faces, which project farther forward. Imagine looking at a profile of someone's face. Now imagine a line drawn straight down from the eyebrows, perpendicular to the floor/ground. Most north/west European-descended people will have only a bit of the bony root of their nose, plus the cartilaginous bridge and tip of their nose projecting beyond this line, and none of their teeth, or perhaps just the incisor teeth in the front. Most Africans, many Eastern Europeans, and most Australian Aborigines, will have browridges, the entire bony root of their nose (plus the rest of the nose) and many of their teeth projecting in the front of this line, perhaps as far back as their premolars. This is known as 'facial prognathism.' It is a genetic difference between various populations of humans from different parts of the world. For an amazing example of this, rent the video "Speed" from the video store and check out the original bus driver. He is an African-American, I assume, and he has huge brow ridges, and a very projecting face. Now contrast him to Keanu Reeves, also in the film, who is of Asian and western European ancestry, and who has a very flat face, not projecting much at all, with none of his teeth projecting beyond a line drawn down from his browridges. All of which is to say that it is isn't *just* the lack of breastfeeding that contributes to people of north/west European descent having small mouths and dental overcrowding. Certainly, the lack of breastfeeding contributes, but even in breastfed children of this population, even those breastfed for years, you will still see problems with overcrowding and lack of 3rd molar (wisdom teeth) development (they will be missing or impacted, or rudimentary). There is often not space behind the 2nd molars for the 3rd molars to erupt. In contract, if you look in the mouth of an adult from most African or Australian Aboriginal populations you will see not only full and normal eruption and occlusion of the 3rd molars, but even 'retro-molar' space, meaning more space in the mandible for teeth behind the 3rd molars (which humans don't have). Thus, we cannot attribute orthodontic problems in the modern US "white" population only to formula-feeding. We have many thousands of years of population differentiation between our ancestors and those of people from other parts of the world. >I have heard a dentist attribute this overcrowding to evolution, > >presumably on the basis that people in breastfeeding cultures are less > >evolved than formula fed societies. Another thing to make me dubious > >about the theory of evolution but that's off topic! You misunderstood what the dentist said/meant. It is true that the overcrowding is due to evolutionary changes in some human populations -- this doesn't make them adaptive. Evolution refers to a change in the gene frequencies in a population over time. It can occur by many processes other than "natural selection for the most adaptive choice at any given time." I don't think the dentist meant to imply that people in breastfeeding cultures are less evolved than those in formula-fed societies. He was more likely referring to the fact that north/west Europeans and their descendant cultures are most likely to be formula-fed today, while many African and Aboriginal cultures are still breastfeeding for several years. End of anthropology lesson for today. Kathy Dettwyler _________________________________________________________________ Chat with friends online, try MSN Messenger: http://messenger.msn.com *********************************************** The LACTNET mailing list is powered by L-Soft's renowned LISTSERV(R) list management software together with L-Soft's LSMTP(TM) mailer for lightning fast mail delivery. For more information, go to: http://www.lsoft.com/LISTSERV-powered.html