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Subject: Re: [working-gundog] epigenetics and the origins of pointing

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cwalt

MH
Posts:180

07/12/2007 8:32 AM
In passing: In humans only 2.5% of the total DNA are genes, that is sequences that code for something. The other 97.5% of the DNA has to be examined more closely. Jere wrote: > 1. Is there an epigenetic change brought about by young dog > interaction with the environment which intensifies the point AND is > inherited from that dog by its progeny? ~~~~~~~~~~~~~~ I have serious doubts starting with the observation that I can perceive no mechanism whereby learning can be transferred to the egg and sperm. If there is an epigenetic influence on pointing it should be lost by FT pointers since their breeding methods emphasize the contribution of males to the genome, how does the dog get 'pointing' into a sperm? This is, of course, strictly a physiological objection that applies to metazoans, specifically mammals. ~~~~~~~~~~~~~ > 2. Is there a gene or genes for pointing? ~~~~~~~~~~~~~ Again, a very doubtful hypothesis. Pointing is a consequence of excitement and that is an emotional state. We haven't postulated genes for happiness or excitement, why start now? Freezing (pointing?) or running are options selected by many animals that are faced with fearful or exciting circumstances. There is either a genetic or epigenetic component to this dichotomy, there is considerable evidence that unhunted populations of whitetail deer (which exhibit both freezing and fleeing) can be shifted from one response pattern to the other by hunting in relatively few generations. When faced with humans with rifles freezers survive much better than runners and eventually the majority of the hunted population will become freezers. Since there is probably a major element of learning involved (did the fawn's mother freeze or run) this could be an epigenetic rather than a genetic transmission of learning, e.g. cultural transmission of information. There is also a sound basis for cultural transmission of information in dogs but I cannot think of any situation where the offspring could learn pointing from their parents. I can document a number of cases where young dogs freeze into a rigid point at first or second scent contact with a bird and they have never had an opportunity to see another dog point. ~~~~~~~~~~~~~~~ > It may be found that there are genes that code for certain chemicals > used in many cellular construction processes such that: > a. these genes exist in the genome as multiple copies, some > "turned on," some "turned off." > b. when these genes are expressed in certain areas of the brain > during the time when neurons are being connected up to form behavior > patterns (such as pointing); more "turned on" genes result in the > production of more of some chemical critical for establishing certain > connections associated with the "intensity" of the associated > behavior, e.g. "point." > c. during this period, interaction with environment can, through > the epigenetic regulating chemicals also on site in the brain, cause > some "turned off" genes to be "turned on" resulting in higher > "intensity" in the individual affected. ~~~~~~~~~~~~~~ It is interesting speculation and I have no intuitive counter arguments. ~~~~~~~~~~~~~~~ > I don't think these details are known now. They will be fascinating. > Can I buy another 50 years? > Jere ~~~~~~~~~~~~~ Certainly, send me a check for $1000 and I'll make the arrangements as soon as the check clears. Cj

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