[ModelBreaker]

Aren't all living humans descendants of survivors of the 1918 flu. Actually, there are people alive now who were born before 1918. Please tell me you realized that.

Should have said 'almost everyone.' So shouldn't it's effect be attenuated this time if the new H5N1 flu is mutating to be similar to the 1918 flu? Acquired characteristics (other than genetic mutations) are not inherited. People still alive no longer have any antibodies to the 1918 flu.

I understand that Lamarck was wrong (mostly). But I assume that pretty much everyone on earth was exposed to the 1918 flu. Some died and some lived. There was surely some genetic factor in whether you lived or died.

I have read that the bubonic plague is less virulent in people who are, for the most part, descendants of people who survived the plague that was the plague when it first hit.

[steve86]

I don't believe any genes were ever isolated to explain individual differences in resistance to the flu, other than perhaps race itself (I am foggy on remembering that). Perhaps if the 1918 flu is reconstituted and retroactive genetic studies are done, it might be possible to do that. However, anecdotal stories suggest that susceptibility was entirely random, given exposure to the flu.

I don't know about generational susceptibility to the plague. I'm sure the plague evolves over time as well. Yersinia pestis is a bacterium, of course.