As someone who grew up on a farm (mostly dairy & wool), I also grew up with the responsibility of keeping a large population (~200+ cattle & sheep) healthy. This was basically a daily task, requiring one to keep close tabs on each animal's health and with my dad as de facto vet.

The issue with large populations is that they get sicker quicker, also depending on whether they are kept outdoors (fields), or indoors (stables).

The more you keep animals indoors, the worse their health gets and the quicker they get sick.

The more you pack animals together, the quicker they will spread an illness to the other animals in the population. This meant a careful application of antibiotics to nip infections in the bud, or calling in the vet to handle more severe cases.

We kept our animals outdoors in the fields whenever it was possible. They don't mind a little bit of rain, after all.

What I learned from these many years of raising cattle and sheep is that human cities are the equivalent of cramming cattle together with zero outdoor time.

By spending a lot of time indoors, crammed together as closely as chickens, cattle or pigs on today's modern farms, humans have made themselves exceedingly susceptible to disease and a decrease in overall health.

Cattle & chickens get low-dose antibiotics, what about humans?

Are we going to pretend that human cities are somehow not going to result in many of the same issues that we can see with animals on today's high-density farms?

From general stress, to a lack of sunlight and fresh air, we suffer the same way a cow does.

On that note, whenever a farm gets hit by a nasty outbreak of a disease that didn't get nipped in the bud, the solution is to kill (euthanise) all animals in that stable or on that farm and dispose of the corpses as hazardous waste.

What about us human animals?

We humans can presumably be told to do things that should keep us safe, whereas a cow, pig or chicken cannot.

Theoretically we will even follow those instructions.

Are humans in a crowd more than easily panicked animals?

Maybe it's due to my farming background, but to me the parallels between keeping farm animals and governing a human population are unmistakable. And with how it how to keep either healthy.

We are still animals, after all, just ones who learned to govern (and exploit) ourselves.