Message Number: YG1933 | New FHL Archives Search
From: Sukie Crandall
Date: 2001-03-31 22:08:00 UTC
Subject: Re: Dr. Williams - Experience begets Understanding?,

Bruce then Brett wrote:
> > Other people may point to dietary influences, the influence of
>> photoperiod, etc., but a genetic background appears to be the most
>> able to explain the tremendous differences in ferquency between
>> American and non-American bloodlines.
>I would agree that genetic effects are likely to be significant, but
>I'm not ready to say they're *most* significant. After all, we
>consider a trait to be highly heritable if additive genetic variation
>explains only 30-40% of the phenotypic variation, leaving 60-70% to be
>explained by environmental causes. And *that* occurs ONLY among groups
>of animals born in the same year/season, in the same herd, and managed
>alike. When you look at variation *across* herds, the genetic portion
>drops precipitously.

There are also always those possibilities that suddenly erupt from
left field. For example, how may of us tend to think about the
arsenic content in our drinking water? Yet, arsenic has been shown
in a large number of studies to be one of the controllable factors
that DOES to a decent percentage of human bladder cancers, as well as
being a known trigger of diabetes in humans, hypertension in humans,
and other things. This stuff is hitting the popular science press
like Science News only now that two things have happened: the
planned improvements in water standards were dismantled, and a
research group at Dartmouth has come up with a mechanism showing how
the mineral acts as an endocrine disrupter by interfering with
glucocorticoids. My point is that there are hidden differences
between countries just as between regions; places where differences
in regulations create variations which simply don't readily catch the
eye, but may be just the influence that needs to be found.


A clarification about my earlier bedding comments. I do NOT know if
bedding does contribute to the furballs, but I do know that at this
point I can't discount that it might. It doesn't seem to be a
question that has been looked into at this point.