krista@ihlpa.ATT.COM (K.J.Anderson) (07/02/87)
Well, I was quite surprised to read a posting about Kalahari Bushmen which claimed that the Bushmen are genetically different from other people in the following ways: a) A camel like hump adapatation, for water storage, b) Sterile offspring from marriages to other groups, c) Over 50% of the population has number of chromosomes not = 46. Because I've read several books about anthropology and never heard of such a thing, I went to the library to check it out. Well, I suspect that the original poster's memory played tricks on him! It happens to everyone sometimes. Nowhere could I find any mention of chromosome differences among so called "races", and I did skim through several books including _Encyclopedia Britannica_. However, I did find some quotes that the memories of which could be twisted by the ravages of time. :-) a) "[Bushmen]...are extremely hardy: the fat on the women's buttocks and thighs is a reserve for lean times, rather like a camel's hump. Noone is sure where they came from and their Mongol strain is a mystery." [1] This extra fat deposit is called steatopygy. But all women have fat on their buttocks and thighs! And everybody's fat cells function as storage. It is a matter of degree, not a difference in the genetic map. As for the mystery, the authors mean it is a historical mystery, not a biological one. b) "There is another possible reason why families are small. According to the Bushmen themselves their women are naturally sterile during the dry season." [1] Here again, note that cessation of menses is not uncommon among female professional athletes, or under other circumstances where the body is unprepared for pregnancy, regardless of the woman's ethnic background. Two of the books mentioned intermarriage with other groups (besides Hottentots) but made no mention of any problems. c) "Were we to build a human family tree on DNA sequences alone, it would be branchless. No significant differences between our races could be seen. All of us, from Eskimo to Australian aborigine would be genetically as alike as peas, and almost as closely related to chimpanzees as we are to one another." [2] Now, this same resource goes on to discuss "... distances between the chemical components in the codons in the blood of three racial samples...", and does find significant differences in the presence or absence of subsets of thirty *proteins*, not chromosomes, so maybe that's what the original poster was recalling. There are also studies of blood types and factors, but it is hard to make conclusions because we cannot determine whether a certain population never had a particular gene, or whether it once had the gene, but it was bred out. Coon, in [3] discusses blood types. Even in blood studies, we must realize that presence or absence of a factor does not suggest a *structural* difference in the chromosomes. Anyway, my point is that while there are physiological variations that may be geographically grouped, there is no evidence of subspeciation. Indeed, Montegu criticizes Coon for exaggerating the significance of regional variations. Montegu thinks that the concept of race is a social idea rather than biological reality. [4] In _The Monkey Puzzle_, the authors agree with that opinion. Some molecular DNA studies have shown no real distinction among the so called races. The genetic variations among individuals of one population are about 6%. The genetic variations of the means among different populations are, uh, 6-7%. In other words, the physical adaptations that we see in different parts of the world are still within the limits of normal species variation. [5] There still are puzzles, however, including a group of people whose mitochondrial DNA differs from the rest. Because mitochondria seem to be neutral, they provide a measure of historical mating patterns. Most people's mitochondrial DNA shows that they have shared the same gene pool for 40,000 years. The other group's mitochondrial DNA puts them in an older gene pool - 100,000 years. [5] References: 1) _Peoples of the Earth_, Volume 9, published by Grolier. 2) _Racial Adaptations_, by Carlton Coon. 3) _The Living Races of Man_, by Carlton Coon. 4) _The Fallacy of Race_, by Ashley Montegu. 5) _The Monkey Puzzle_, by John Gribben and Jeremy Cherfas -- ihnp4!ihlpa!krista - I can't help it, I'm just a baby ape.
duncan@csd4.milw.wisc.edu (Shan D Duncan) (07/11/87)
In article <4505@ihlpa.ATT.COM> krista@ihlpa.ATT.COM (K.J.Anderson) writes: >which claimed that the Bushmen are genetically different from other >people in the following ways: > >a) A camel like hump adapatation, for water storage, >b) Sterile offspring from marriages to other groups, >c) Over 50% of the population has number of chromosomes not = 46. > >Because I've read several books about anthropology and never heard [ List several reasons for the low birth rate among the Bushmen (and women :-) ) ] > >a) "[Bushmen]...are extremely hardy: the fat on the women's buttocks >and thighs is a reserve for lean times, > >b) "There is another possible reason why families are small. >According to the Bushmen themselves their women are naturally >sterile during the dry season." [1] Here again, note that cessation >of menses is not uncommon among female professional athletes >ihnp4!ihlpa!krista - I can't help it, I'm just a baby ape. Add to his points above. The reason I heard for the cessation of menses among female athletes is a very low body fat percentage (the estrogens being STEOIDS and fat soluble... perhaps?). Bushmen tend to nurse their offspring for what we westerns consider to be a long time (2-3 years). In many cases this can act as a form of birth control (continued elevated oxytocin levels). Finally humans are not very fertile to start about 30% under the "best" conditions. To compare most farm animals are about 80%. This is not unusual since humans have a relatively long breeding life span and infant care last an fairly long time. [ These properties were once refered to as K-selected atributes... ]. So. All in all there really is only one species of human alive today using the Biological Species Concept (Actually the Zoological Species Concept). --------------------------- duncan@csd4.wisc.milw.edu | ---------------------------
jnp@calmasd.GE.COM (John Pantone) (07/15/87)
Shan D Duncan writes: > Add to his points above. The reason I heard for the cessation of menses > among female athletes is a very low body fat percentage (the estrogens being > STEOIDS and fat soluble... perhaps?). Correct. This was first discovered among dancers (ballet) and has been given the name Terpsicore's syndrome (terpsicore being a dancer, not a person). The recent "you can't be too thin" fad has created a new rash of Terpsicore's syndrome cases. The cessation (not always temporary) of menses is only one of many symptoms, included are heart murmmurs, calcium deficiencies and hair loss (accompanied by dry skin). -- These opinions are solely mine and in no way reflect those of my employer. John M. Pantone @ GE/Calma R&D, Data Management Group, San Diego ...{ucbvax|decvax}!sdcsvax!calmasd!jnp jnp@calmasd.GE.COM
gagen@bgsuvax.UUCP (kathleen gagen) (07/15/87)
In article <4505@ihlpa.ATT.COM>, krista@ihlpa.ATT.COM (K.J.Anderson) writes: > There still are puzzles, however, including a group of people (Bushmen) > whose mitochondrial DNA differs from the rest. Because mitochondria > seem to be neutral, they provide a measure of historical mating > patterns. Most people's mitochondrial DNA shows that they have > shared the same gene pool for 40,000 years. The other group's > mitochondrial DNA puts them in an older gene pool - 100,000 years. [5] > I'm not sure that it would be accurate to say that mitochondria porvide a measure of historical "mating" patterns. So far as is known, mitochondrial DNA is extreemly highly conserved. This may be, at least in part, because mitochondrial DNA is involved in the essential function of cellular respiration. So far as is known, all of the mitochondrial DnA of any individual is identical. Unlike nuclear DNA, mitochondrial DNA is of MATERNAL origin. In other words, all of your mitochondrial DNA is inherited from your mother, who inherited it from her mother etc. Kathi Gagen -- Kathleen Pausic Gagen ...!cbosgd!osu-eddie!bgsuvax!gagen Dept. of Biological Sciences gagen@research!.bgsu.edu Bowling Green State University gagen%bgsu.csnet@csnet-relay.arpa Bowling Green Ohio 43403 gagen%andy.bgsu.edu@csnet-relay.csnet
takashi@rlgvax.UUCP (Takashi Iwasawa) (07/17/87)
In article <2310@calmasd.GE.COM>, jnp@calmasd.GE.COM (John Pantone) writes: > Correct. This was first discovered among dancers (ballet) and has been given > the name Terpsicore's syndrome (terpsicore being a dancer, not a person). > ....< stuff deleted> .... > -- > These opinions are solely mine and in no way reflect those of my employer. > John M. Pantone @ GE/Calma R&D, Data Management Group, San Diego > ...{ucbvax|decvax}!sdcsvax!calmasd!jnp jnp@calmasd.GE.COM Terpsichore IS a person, though not a human being. She is the Muse of Dance in the Greek pantheon. Takashi Iwasawa