Once upon a time man lived in very close proximity with all sorts of domestic animals - in the same room as the pigs for example. We have been gradually distancing ourselves, though dogs, cats, hamsters may still be considered as acceptable domestic companions
We lived with livestock partly for warmth, partly for convenience, partly out of economic necessity. Who would spend time or good money building them a house of their own? But we had no compunction about killing them for food, & eating everything but the whistle
In a cold climate a source of warmth is essential for human survival. But humans were also aware from the earliest days of the dangers of heat - not least because fever was a symptom of the most dangerous of diseases
We mostly think of humans as special beings, apart from animals. But most of us are at least a bit confused by animal rights arguments about the status of chickens & pigs.
The old suspicions about animals as a source of disease persist, but are confused with, or by, a new suspicion of 'chemicals' in our food, which are unnatural & therefore clearly more dangerous than 'natural' animal sources. At its most confused, the 'natural' (prions, e coli) become confused with the chemical & lack of ice cold hygiene
As we became wealthier & more fastidious we ate only the best bits of animals & distanced ourselves from their owners warm but messy ways. This distancing saved us from some infections at the cost of introducing new dangers such as BSE; it also posed new problems of how to dispose safely of the parts we did not wish to eat.
A bright clean supermarket selling plastic wrapped premium cuts may seem more hygienic than a bloody butchers shop with sawdust on the floor but, out of our sight, what happens behind the scenes to all that blood, bone, offal & fat which we now reject?
Was primitive vegetarianism a feature simply of warm wet countries, where the climate & soil could provide an adequately balanced vegetarian diet for humans? Or of a climate which would provide a particularly dangerous combination, the ideal circumstances in which bugs could breed, one where the combination of warmth & wetness & animals should be avoided ?
Modern hygiene is a conflicting combination of heat & cold; boiling water to kill off the bugs followed by refrigeration to keep them at bay.
The first stage - the boiling water - like the animals - is increasingly pushed into the background and hygiene is equated with cold, clean, clinical.
Global warming is our fear, not a renewed Ice Age
The pig served as an auxiliary department of sanitation right down to the 19th century, in supposedly progressive towns like New York & Manchester - Lewis Mumford