Early American Indians

[ravenwing5910]

ok, I may be way off base here, but isn't it accepted that infants (of any mammalian species) acquires immunity from the breast milk? perhaps this doesnt explain genetically passing on immunity but it would indicate that immunity is passed from mother to infant. And the Sickle Cell Trait, would have to be a genetic mutation in response to malaria wouldn't it? and that is passed from either parent. It is only when the Trait becomes anemia that it poses a problem.

[Digit]

Eactly Cog, if there is a definite dateable lineage to a given disease it could produce some interesting ideas.
Monk, if a persons genetic make up causes them to be immune to a given pathogen then that will be inherited. This is the usual explanation to the steadily reducing death toll in Europe to the Plague.

[Forum Monk]

R/W follow these pages for info on colostrum in breast milk. Only the childs natural mother can pass it and it offers limited protection.

http://www.healingdaily.com/conditions/colostrum.htm

[Forum Monk]

Eactly Cog, if there is a definite dateable lineage to a given disease it could produce some interesting ideas.
Monk, if a persons genetic make up causes them to be immune to a given pathogen then that will be inherited. This is the usual explanation to the steadily reducing death toll in Europe to the Plague.

How about the evolution of the virus into something less pathogenic? Can you show me some research?

[Digit]

Yep! But don't ask me find the links tonight Monk but one I can tell you about and that is to look up Mxamatosis in Rabbits, it is fully explained in some sites I read some time back.

[Cognito]

How about the evolution of the virus into something less pathogenic? Can you show me some research?

FM, the answer to that one comes from Pathology 101 and is almost taken for granted. When virulent diseases "jump" from animals to humans they tend to be quite deadly at first. If you think about it, it's not a good strategy to kill hosts too quickly. The most successful diseases are the ones that have attenuated over time. Natural selection favors those diseases that make you just "somewhat sick" and allow for future transmission to new individuals. The lethal killers don't transmit as effectively since ... after all ... you're dead ... end of transmission.

The bottom line: Pathological attenuation is driven by the requirement to transmit effectively through host vectors.

[Forum Monk]

I agree Cogs. I was actually arguing against the idea of inherited immunity but I believe an organism will mutate into a less deadly form, as you well point out.

[Cognito]

I agree Cogs. I was actually arguing against the idea of inherited immunity but I believe an organism will mutate into a less deadly form, as you well point out.

Inherited immunity does occur but it is very rare. Every population will contain a few individuals who possess genes that confer immunity to a disease lethal to others. In Europe those individuals who were immune to the plague were slowly selected over time as the plague returned over and over. As I recall, studies showed that the estimate was originally less than 1% moving to 10% of the European population over centuries. Native Americans never experienced the plague so their first hit was similar to the first exposure in the Old World ... Big-Time Wipeout. However, some natives were immune due to good genetics. Some or all of their offspring also were immune, etc. It happens, but by natural selection.

This is similar to the dandelion discussion on another thread earlier. The shorter dandelions were always in the yard along with the larger ones all the time, vying for sunlight among their larger brethren. When the lawnmower came along they were selected over the tall dandelions when the lawn was mowed every week. They didn't just "transform" themselves, they were there all along. The environment changed, not the dandelion.

[Digit]

Exactly Cog, and once the immunity levels within a population reach a ceratin level that immunity will increase rapidly.
This has of course been the problem with pesticides and anti-biotics, a 1% immunity level in a previously unexposed population running into millions within a short time makes the pesticide etc useless as natural selection selects the immune individuals and leaves them to breed.

[Forum Monk]

It's a well known fact, as Cogs pointed out, that nature favors less deadly organisms. Thank God that nasty stuff like ebola tends to be self-limiting since it kills its hosts before it can spread too far. But as far as immunity, there are two forces at work. You have the slowly progressive possibility of natural selection for more resistant hosts and you have the much faster mutating virus selecting for better infection strategies or what ever increases their survivability. The two are working against each other and frankly, since the virus will reproduce trillions of generations in a few years, I am not sure how our little 'ole immune systems can even stay ahead of the game.