SC - SC: an immunology lesson :) OOP

[Anne-Marie Rousseau]

Hi all from Anne-Marie...
> At any rate, we also have to take into consideration the fact that the
> humanbody was very obviously different several hundred years ago.
> The time line thingy, conditions back a few hundred years and the fact
> that there were not new and improved killer diseases makes for a
> completely different resistance system. Now I may be out of my element
> here but given the fact that were are a biologically evolving species I
> just bet we may have had a whole different system of flora and fauna
> in our systems then than now. Perhaps coping with the "little beasties"
> was easier then? Does anyone know the differences between "then
> and now" as far as our resistance is concerned?
> 

I am an immunologist. That's how Imake my living. So I feel qualified to
address this.

The human body and its immune system are exactly the same now as they have
been for thousands of years. Where you get into differences is in the
resistance, and that can vary from person to person in a room now. This
resistance is not a genetic thing, its generated by our immune systems when
we're babies. The folks in the middle ages no doubt were very resistant to
the buggies that were floating around their world, just as we are resistant
to the buggies in ours. Where you start getting into trouble is when a new
bug comes on the scene. Smallpox to the First Nations. Tourists go to
mexico (or even a different city in the US....different bugs can do a
tapdance on your colon, no matter how harmless they are to locals).
Crusaders bringing back new cooties from the far east. Your kid goes to
daycare.

We dont have fewer bugs now, we just do a better job of killing them off
(whether this is a good thing or not is undetermined). Everyday I make
herculean efforts to keep my precious cultures from picking up mold,
bacteria, yeast and viruses that are floating about even in our filtered
building air. Any one of these could cause sickness and even death in a
human being (now or in the middle ages), but our immune systems, combined
with our normal flora, when working properly, keep them at bay. Imagine the
cooties if I was to attempt to do tissue culture outside!

It is a common misconception to assume that life in the middle ages was
more "pure" than now, or that Joe-medieval-guy was in some way a more
primitive human being. 1500 years of selective breeding can do some amazing
things (look at the chihuahua!), but it is my professional opinion that it
is unlikely that the genetic material making up the immune system has
undergone any changes in that time. We're not talking about a single gene,
or even a single chromosome to get mutated....its an amazingly complicated
thing. To suggest that its been genetically changed since the middle ages
would be similar to suggesting that maybe we didnt used to have two legs,
two arms and skin on the outside of our bodies.

Remember boys and girls, resistance is not inherited, not in the
immunological sense. Resistance can be conferred from one individual to
another, but I rather doubt that anyone was or is isolating T or Bcells
from their buddies and injecting them IV (which is the primary procedure to
accomplish this. The others involve organ transplant and whole body
irradiation...you get the idea). Resistance is generated either when a body
meets a bug and defeats it, making antibodies for future protection, or by
getting antibodies from ones Mom when nursing. This basic process has not
changed in the period we are discussing.

I rather agree with Ras that as a population we're getting weaker, but the
bell shaped curve remains the same. the basic genetic material has not
changed, its just that we got lots more sickies around breeding :)!

Hope this makes sense...just like I get a little twitchy when folks throw
the idea of "allergy" around willy nilly (an allergy is a very specific
immunlogic and histochemical reaction), the idea that genetics are the
answer to everything, or the idea that radical evolution can happen in a
few hundred years goes against everything I know.

- --AM
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