From John Naish article on the ‘science’
History shows that viruses which evolve in animals and jump species to infect humans are among humankind's most dangerous and enduring foes.
Pandemic flu, for example, originated in poultry and pigs. Measles came originally from cows.
Newly-emerging killers such as Ebola, SARS and Covid-19 came from bats. Once the viruses learn how to 'shape-shift' in this way, they can go on to acquire even more lethal powers.
The concern comes down to this: when the virus jumps from humans to other animals, it can effectively learn deadly new tricks that may make it more infectious, more deadly and might enable the virus to defeat the best drugs or vaccines. This learning process is called 'viral recombination'.
It happens when two different virus strains infect the same animal cell, co-mix, then produce new viruses that have some genes from both 'parents'.
Thus, instead of finding a vaccine to defeat Covid-19 once and for all, we could end up playing an endless game of smack the rat (or cat, or mink, or bat, hamster, ferret, or macaque — they've all been found Covid-infected), as the virus continuously mutates, shifts species then returns to re-infect us again.
It is in intensive farming — such as the mink industry — that this threat becomes most alarming.
When a virus spreads rapidly through a large, dense pop- ulation (animal or human) it can evolve into ever-deadlier forms even faster.
Because, in this situation, it does not matter if the virus kills its host extremely quickly (and so reduces its own chance of survival) — it can easily jump across to another of the same species, and simply claim victim after victim in a vast murderous spree.