>From: "Robert C. Cline" <rccline_at_swbell.net> >As for Schurke's experiment, I don't dispute that there is a process of >acclimatization, or that there are physiological differences between >populations or individuals descended from racial groups which have had >10,000 years of exposure to a particular climate. What I suggest is, that >there does not appear to be any scientific articles by Schurke published, >or >at least indexed in the scientific literature on the web; no evidence of >controls, and actually not a very "scientific" experiment. Interesting, and the cobwebbed hollows that pass for my memory prevent me from citing a source, but I thought I'd read somewhere that studies with Arctic fishermen had suggested there was actually a process of neovascularization (spelling?), that is the individuals actually grew additional blood vessels in their hands which allowed them to shunt greater quantities of warm blood into the extremities. Sounds plausible to this layman - our muscles, red blood cell count, resting heart rate and so on certainly respond to exercise, exposure to altitude, etc. On the other hand, I suppose it could be a desperate rear-guard action by the last of the LaMarckist evolutionists, surrounded by Darwinists. Any doctors or scientists on the list care to comment on the possibility of this "change in the phenotype"? Philip Torrens N49°16' W123°06' *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
Philip Torrens wrote: > [snip] I thought I'd read somewhere that studies with > Arctic fishermen had suggested there was actually a process of > neovascularization (spelling?), that is the individuals actually grew > additional blood vessels in their hands which allowed them to shunt greater > quantities of warm blood into the extremities. Maybe, but not needed to explain the effect. See below. > Sounds plausible to this layman - our muscles, red blood cell count, resting > heart rate and so on certainly respond to exercise, exposure to altitude, > etc. On the other hand, I suppose it could be a desperate rear-guard action > by the last of the LaMarckist evolutionists, surrounded by Darwinists. > Any doctors or scientists on the list care to comment on the possibility of > this "change in the phenotype? Far more likely is that the process of normal vasoconstriction in response to cold water immersion has been modified -- so that vessels which would have previously closed down get "reprogrammed" to stay open. Reason I support that explanation is the 6-week time for filletters (see my previous post): probably too short a time to generate a lot of vascularization (micro or macro). I've noticed this acclimatisation effect in me when I used to XC-ski regularly. Lots greater tolerance of cold on my hands at the end of the season. -- Dave Kruger Astoria, OR not an M.D. *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
> Philip Torrens wrote: > > > [snip] I thought I'd read somewhere that studies with > > Arctic fishermen had suggested there was actually a process of > > neovascularization (spelling?), that is the individuals actually grew > > additional blood vessels in their hands which allowed them to shunt greater > > quantities of warm blood into the extremities. > > Maybe, but not needed to explain the effect. See below. > > > Sounds plausible to this layman - our muscles, red blood cell count, resting > > heart rate and so on certainly respond to exercise, exposure to altitude, > > etc. On the other hand, I suppose it could be a desperate rear-guard action > > by the last of the LaMarckist evolutionists, surrounded by Darwinists. > > Any doctors or scientists on the list care to comment on the possibility of > > this "change in the phenotype? > > ... I know virtually nothing about the topic, but there is a behavior that some organisms (e coli, rats, some plants, humans) exhibit that is called "heat shock response" that might be at play, at the molecular level. As I understand it (which may be off), when exposed to temparatures significantly over or under what the organisms are used to, heat shock response factors (proteins of some sort) activate the synthesis of heat shock proteins (hsp's) through RNA-transcription. These heat shock proteins serve to regulate and repair damage to cells at the more extreme temperatures. Apparently, hsp generation can continue for several days after the initial heat shock. I imagine that continued heat shock would result in a continuous generation of the heat shock proteins required to allow the organism to survive in the more extreme temperatures. The behavior is consistent with the observation that after the heat shock is removed the tolerance dissipates. BTW, I got this info from a friend who minored in molecular biology in college. Any current biological experts care to comment on this theory? Evan *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
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