sadoyama@pavepaws.berkeley.edu (Eric J Sadoyama) (07/18/86)
In article <2588@mit-eddie.MIT.EDU> stever@mit-eddie.UUCP (Stephen Robbins) writes: > There are certain genetic considerations between MOTOS >incest, but other than that, I don't consider it my place to dictate >what people can and can't do. I've heard this reasoning many times, but never any proof or evidence for it. How is this any different, genetically, from the situation in herds, or other animal living groups, where the dominant male mates with *all* the females in the group, be they related or not? --- Eric J Sadoyama 2033 Haste St #107 Berkeley CA 94704 USA (415)548-1711 or (on break): 942 Hoomoana St Pearl City HI 96782 USA (808)455-4276 sadoyama@pavepaws.berkeley.edu or {backbone}!ucbvax!pavepaws!sadoyama
ambar@mit-eddie.MIT.EDU (Jean Marie Diaz) (07/21/86)
In article <892@ucbcad.BERKELEY.EDU> sadoyama@pavepaws.UUCP (Eric J Sadoyama) writes: >In article <2588@mit-eddie.MIT.EDU> stever@mit-eddie.UUCP (Stephen Robbins) writes: >> There are certain genetic considerations between MOTOS >> incest [....] > >I've heard this reasoning many times, but never any proof or evidence >for it. How is this any different, genetically, from the situation in >herds, or other animal living groups, where the dominant male mates with >*all* the females in the group, be they related or not? [I'll use horses as my example; I have a reasonable amount of expertise there.] It was a long-cherished belief in the horse world that the herd stallion kicked 2-3 year old males out of the herd, but not females. More reaearch has proved this wrong--the fillies are removed from the herd as well, when they near breeding age. There is a lot less 'incest' in this species than was once thought. Inbreeding [or 'line-breeding'] is a well-known breeding tool. It 'fixes' good characteristics in a given genetic line. What breeders ALSO must remember is that the bad characteristics are 'fixed' and purified at the same time! It's not a very good idea to do this, unless the animal you are starting with is a truly exceptional individual. -- AMBAR "I need something to change your mind...."
lonetto@phri.UUCP (Michael Lonetto) (07/21/86)
In article <892@ucbcad.BERKELEY.EDU> sadoyama@pavepaws.UUCP (Eric J Sadoyama) writes: > >I've heard this reasoning many times, but never any proof or evidence >for it. How is this any different, genetically, from the situation in >herds, or other animal living groups, where the dominant male mates with >*all* the females in the group, be they related or not? Most (if not all) herding animals choose dominant males in ways that decrease the incidence of incest. A typical means is for females to remain with the the herd (thus highly related) while juvenile males are driven from the herd. When the males are fully mature they can attempt (individually) to take over herds, however, typically lone males wander much further than the herd does, thus the chance of taking over one's maternal herd is reduced. This is a simplification of the system used by lions. Chimpanzees have a similar means of dealing with the problem. I'm not familiar with how ungulates decide. Incidentally, there is good evidence, both human and animal, that close inbreeding can lead to problems. The European royal family bred amongst itself for some centuries and managed to unmask some unpleasant recessive genes that they were carrying, including hemophilia. When any small population breeds only within itself the frequency of homozygous recessive genotypes will increase. Most often such genes have no heterozygous phenotype, including in the presence of other heterozygous recessive mutations. Putting two of the same recessive gene in the same person (animal, plant, etc) causes problems. Michael Lonetto UUCP:(allegra!phri!lonetto) USMAIL: Public Health Research Institute, 455 1st Ave, NY, NY 10016
victor@batcomputer.TN.CORNELL.EDU (Victor Balaban) (07/22/86)
>> There are certain genetic considerations between MOTOS >>incest, but other than that, I don't consider it my place to dictate >>what people can and can't do. > >I've heard this reasoning many times, but never any proof or evidence >for it. How is this any different, genetically, from the situation in >herds, or other animal living groups, where the dominant male mates with >*all* the females in the group, be they related or not? > Actually in herds there is always new genetic mterial coming in because the new dominant male is often a loner who challenged tthe dominant male and won. This is often why young males leave their herds in search of new ones, preferably one with an old dominant male ready to be toppled. -- Victor Balaban "Rationalizations can be more important than sex, when's the last time you went three days without making a rationalization?" - David Lee Roth
simpson@lll-crg.ARpA (Rea Simpson) (07/22/86)
In article <892@ucbcad.BERKELEY.EDU> sadoyama@pavepaws.UUCP (Eric J Sadoyama) writes: >I've heard this reasoning many times, but never any proof or evidence >for it. How is this any different, genetically, from the situation in >herds, or other animal living groups, where the dominant male mates with >*all* the females in the group, be they related or not? > I think it has to do with the fact that you and your close relatives have a lot of the same genes in common. So if you have a "bad" recessive gene in the family, mating with a relative will increase the chance of that gene rearing its ugly face. There's no guarentee that mating with someone outside your family will not result in the same thing, but your chances are probably better. Rea
robert@weitek.UUCP (07/23/86)
The value of inbreeding as a breeding technique depends on the willingness
of the breeder to exercise merciless culling. In animal breeding, the animals
that show undesirable recessives are destroyed. In human society, this is
frowned upon. Without culling, inbreeding is at least as effective at
promoting undesirable characteristics as desirable ones.
For all that, I've heard that a single generation of inbreeding doesn't up
the ante very much, and that first-cousin marriages are sufficiently distant
genetically that they aren't a big problem, so long as ALL breeding in that
line isn't equally close.
--
Robert Plamondon
UUCP: {turtlevax, cae780}!weitek!robertmayville@tybalt.caltech.edu.Caltech.Edu@cit-vax.Caltech.Edu (Kevin J. Mayville) (07/26/86)
>> There are certain genetic considerations between MOTOS >>incest, but other than that, I don't consider it my place to dictate >>what people can and can't do. > >I've heard this reasoning many times, but never any proof or evidence >for it. How is this any different, genetically, from the situation in >herds, or other animal living groups, where the dominant male mates with >*all* the females in the group, be they related or not? > >--- >Eric J Sadoyama 2033 Haste St #107 Berkeley CA 94704 USA (415)548-1711 >or (on break): 942 Hoomoana St Pearl City HI 96782 USA (808)455-4276 >sadoyama@pavepaws.berkeley.edu or {backbone}!ucbvax!pavepaws!sadoyama There is really no difference, genetically, between these two sitautions. In most cases, incest produces no problems (genetically, that is) in offspring at all. However, suppose the dominant male has a very rare, very deadly, recessive gene. If he mates with another, random cow, there is an astronomically small chance of a double recessive occurring. Now, however, assume he mates with one of his female offspring. Approximately half of them will also be carriers of this gene. Out of every four young resulting from this union, two will be carriers of this deadly gene, and one will be a double recessive, and will be stillborn, or possess whatever nasty trait this gene causes (perhaps hemophilia, if the dominant male is of European Royalty). You can see the devastating results for the gene pool if this dominant male mates with his grandchildren. The main objections against incest are, of course, inspired by other people's concepts of morality, but the genetic considerations are somewhat valid. Hope this clears up some confusion. Kevin Mayville