From Food To Guns Germs And Steel Summary

chapter 11 is the first in Part 3, which is entitled "From food to guns, germs, and steel". Earlier chapters traced how food production rose up is a few areas and spread, at different rates, to other places. This Part begins to show how this change in food production led to the Eurasians getting the guns, germs and steel, which, in turn, led to the answer to Yali's question about why they had all the 'stuff'.
When farmers meet hunter gatherers, Diamond points out, the farmers "tend to breathe nastier germs, to own better weapons and aror, to own more powerful technology in general, and to live under (controlled by one central place) governments with able to read and write rich, powerful people better able to wage wars of victorious capture/romantic relationship".
Chapter 11 is

about why farmers tend to have nastier germs.
Diamond first goes briefly over some of the ways germs spread themselves, illustrating with sicknesses such as trichonosis (which has to be ate), to those transmitted by insects ((dangerous disease), disease, (disease spread by insects), sleeping sickness), to those which change the host to make spread easier (syphillis), to those which cause the host to help spread the disease (flu, cold, (dangerous disease with cough), disease (that causes diarrhea)).

He also notes that bacteria change (and get better) more quickly than do the hosts, since they have shorter lifespans.
He then explains why many sicknesses happen as widespread diseases; such sicknesses tend to have (more than two, but not a lot of) (features/ qualities/ traits) in common: 1) They spread effectively from an infected person to a healthy one. 2) They are sudden and short-term rather than long-lasting - you either recover or die. 3) Those who recover become unable to be harmed and 4) They are mostly restricted to humans. This makes these sicknesses "crowd sicknesses". A disease cannot spread from person to person if people aren't in close contact on a regular basis.
How does all this relate to the central idea? Here's

how:
First, because farming and raising farm animals allows denser (groups of people/animals/things), it allows the spread of disease in ways that hunting and gathering does not. But the (groups of people/animals/things) then become unable to be harmed (either in whole or part) to the illness. When they meet up with peoples who do not share that (not able to be harmed/not able to get a disease), the last thing just mentioned group is destroyed.
Second, farming-based (communities of people) are not short-lived, so they live in the middle of their own sewage. In fact, many use that sewage as fertilizer.
Third, in farming-based (communities of people) many people live close to animals, and we get a lot of sicknesses from animals.