Man first lived in the jungle. He ate fruits, nuts and berries, and was happy.
Then he started hunting in the plains. Meat entered his diet.
Infants were reared on mother's milk, and when they were weaned, they stopped having milk. Which was as it should be.
Now, man noticed that all mammals fed their young. Man thought, why not take that milk and have it ourselves?
He realised that the milk of other animals would be particularly suited to their young, and not to Man. For, being wise, man knew that that is how God made the world.
However, man being man, still went ahead. He found that the milk of goats was the most suitable for humans. However, goats did not produce much milk. Then he looked at the cow. The cow was a docile animal, easy to manage, and it gave a lot of milk. The milk of the cow was not really suited to the human body, but man went ahead anyway. He started keeping cows.
Over a period of time, those people who reared cows and had its milk learnt to digest it. Given enough time, man learnt to digest anything, for that was how God made man. Some of these communities only took the milk from the cow, and converted it into tasty things like butter, ghee, curd and the like. Some communities even drank the blood of their cows, in small quantities at a time, so they were not only milking them, they were also blooding them.
And thus, milk became a part of the diet. At the same time, there were peoples across the world who could not digest milk, since they never had it, unlike the pastoral people, of say, the Northern part of what is now called India who kept cows and had lots of milk.
These pastoral people of India not only depended on the cow for their milk, they elevated the cow to something holy. They started worshipping the cow. Somehow, this meant that they could seize the milk from the cow meant for its calf, but they could never kill it. Killing a cow was decreed to be a sin worse than killing a Brahmin, and killing a Brahmin was a heinous sin, naturally, since the Brahmins wrote the scriptures.
The pastoral people raised cows. The cows were taken to the jungle by the cowherds, and they munched on natural rain-fed grass, in peace and contentment, while the cowherds played the flute and kept them entertained. The cows were treated like part of the family and they were well cared for. So the milk that the pastoral people had was happy milk. And they prospered.
The many other people who did not keep cows nor have their milk, prospered too, on diets which did not include milk.
And then, ages flew by. People across the world had milk, or did not, depending on where they were from.
And then man arrived in the modern age. Where everything was being industrialized. Scaled. Multiplied. Distributed. Commoditised. Made more freely available.
Milk had to go the same way. There were many people staying in the cities in India who wanted milk. Not least because they were addicted to chai and coffee. They also made many sweets and delicacies from milk, and learnt to like them, and crave them.
So they established milk factories. And they started collecting milk from across the countryside. And transporting it to the milk factories. The farmers who supplied the milk to the factories started keeping different cows for themselves and different cows for supplying to the factories. The milk of the same cow which would not be used if she was not well, was now usable, for supply to the factories. They changed the diets of the cows also, to save money, since now they were breeding cows to make money from selling the milk, and not merely to supply milk to their family and village.
The people from the factories collected all the milk and put everything in the same can and mixed it up. The milk from good cows, bad cows, healthy cows, diseased cows, happy cows, sad cows, all got mixed up in the same can. And they transported it to the factories which were far away. Now milk does not take kindly to such transportation. It stated curdling. So the factory people added certain things to the milk, to keep it from curdling, like, for instance Urea. Now people knew Urea was a fertilizer but those who were observant realised that the sales of urea seemed to more in milk producing regions than in regions that did not produce milk.
The milk, still being natural, started becoming bad very quickly. Left outside for some time, the bad germs in the milk started multiplying. The factory people had to stop this, since their supply chain from the time they procured the milk from the villages, to the time they distributed it in the cities, was long, it definitely took at least a day, if not two. So they invented a process called pasteurization which killed all the bad germs. The problem was, it killed all the good germs also. To assure the people that everything was all right, they said that pasteurization is the same as boiling, the boiling of the milk that everyone does at home, and that it actually protects people from catching diseases from drinking the milk. Now they knew that pasteurization was not the same as just boiling, but they continued to say so. And they never admitted that good germs got killed along with the bad germs, though in this, they were very much in sync with their scientific brethren who popularised the germ theory. They always believe that the world is full of only bad germs. And, they want to zap the bad germs. In the process, much of the goodness is lost, but that is not something they talk about.
Now, factory people being factory people, have to "add value" and create products. Else there was no reason for them to exist. So, they started experimenting. They dried the milk into powder with all sorts of chemicals and processes. It was easier to transport, and it would store for months. At the receiving end, someone added water, and voila, it became milk! Except, no one really asked, is that milk? It was just something that looked like milk, tasted like milk, but was not milk. But they could not admit that. So they put their marketing people on the job to keep calling it milk, and people finally started believing that it was milk. People are easy to fool, since if it looks like milk, and tastes like milk, they will accept it as milk.
They even started selling the milk powder as baby food! Milk of another animal, converted to non milk, preserved over a long period, a powdery substance, which they convinced people was good for babies! They again put their marketing people on the job. The marketing people were so good that they convinced people that this powdery substance was actually better for their babies than their own mother's milk!
Then they started creating variants. They sold non-fat milk, half fat milk, thin milk, skim milk… the variants were endless. People thought they were buying milk, but what they were buying was actually a manufactured product that had long since ceased being milk. Even the milk that was sold to them in liquid form was first pasteurised, then homogenised, and during the production process it was mixed with lots of dried milk powders, the chemicalised long-shelf life milk from other places, and what came out looked like actual milk. Now what is homogenization, someone might ask. It is such an innocuous word. Homogenize! Who would not like something that is homogenized, it has such a sanitised feel to it. Well, actually, customers started complaining that they did not like the fact that yellow fat started rising to the top of the milk after boiling, when the milk was cooling. So they said, let us break down the fat molecules, so that they stay integrated, rather than separating as cream. So what did they do? They passed the milk through a very very thin mesh at high pressure. Such high pressure that it is equivalent to about 70 times the pressure in a car tire, at 2400 psi. The molecules broke down. This changed the chemical structure of the milk itself, and the body could no longer recognise it as milk, and appropriately digest it, but no matter. They continued calling it milk.
They again put their marketing people on the job. The marketing people were so successful at their job that people started believing that the milk they got from the packets was better than the milk they got from cows. So people stopped drinking milk from cows. They were convinced that milk from cows directly is unhealthy. In many countries, especially in the US, selling raw milk directly was banned by law.
Meanwhile, farmers who were selling milk to the factories wanted more "yield" to make more money. So they started injecting hormones into the cow to increase the uterine contractions, thus increasing milk production. This hormone, oxytocin, was the same they gave to pregnant women to induce labour.
The milk-factory people, meanwhile, said, why not raise the cows in a cow farm? Scaling, processising, control, cost reduction, quality, so many justifications came to mind. So they started raising cows in farms. Now when animals are raised in such close proximity, they start getting diseases. So the factory owners started adding anitibiotics in small doses and mixing it along with the food of the cows. These same antibiotics entered the food chain and entered people, and caused antibiotic resistance, apart from the fact of course, that antibiotics themselves are harmful to health.
Meanwhile, milk became an "industry". It itself, from a product, morphed into many products. Each of these products looked like milk, tasted like milk, and felt like milk, but was not milk. But they continued calling it milk. The marketing people were so successful in their job, that all over India today, mothers tell their children "Doodh pee le beta, nahi to thu tandurusth kaisa banega?" and give their children these concoctions they call milk.
Meanwhile, some of the communities that never had milk in their diets to start with, still continue with virtually no milk in their diet. The wise ones say that they are more healthy.