Lactose, its long time relation with human being

Lactose, a substance that is contained in milk. It provides nourishment with human and it is easy to obtain through domesticating mammals like cows or horses. However, it is not always a perfect thing for human.

Some people is tolerant to it, some are not. So called lactose intolerant is a typical issue for human eating habits. This lactose intolerance shows certain characteristic with geographical or human race distribution. In some areas, lactose intolerance is rare, in others it is frequent.

This focus on nutrition winds around to what is the most nutritious food that would have been available to modern humans over the past five or ten thousand years. We finally come to the conclusion that milk is a well-balanced food that provides all three critical macromolecules—protein,

https://blog.education.nationalgeographic.org/2017/11/07/talking-evolution-are-we-still-evolving/comment-page-1/

Typical state of lactose intolerance is stomach pain, diarrhea etc. A person who is intolerant to lactose experiences problem with digestion when the person takes milk.
The mechanism; the person does not have enzyme lactase that plays a role of breaking down it into glucose and galactose.

Anyway, there are certain people who is tolerant to lactose indeed. Why they can be ?Yes, on a whole, human became tolerant to lactose out of necessity throughout its evolution. Human attained the capability from their eating habit. For instance, some nomadic tribes take milk from their livestock. So, they naturally were able to adapt to lactose because milk was one of rare source of vital nutrition due to its relatively stable availability. If the tribes people cannot adapt it, they will lose a chance of survival.

How human body got aware that it is necessary to be tolerant? This function is basically programmed in human DNA, it seems. However, this DNA function have not always existed rather sometime in a past DNA mutated into such form somehow. Maybe some kind of signal was being transmitted to DNA so that DNA could sense the necessity of mutate it self, academics are still seeking the answer though.

In the footsteps of my lactose-intolerant ancestors

https://www.nationalgeographic.com/science/article/in-the-footsteps-of-my-lactose-intolerant-ancestors

So, for modern humans, that mechanism of “let DNA learn” is still working?

What if present food becomes not available anymore? Can we be adapted to another food which are not considered as food presently?

This kind of function might be of lessons-learned System of Lifeforms. This could be one of the key element of “Survival of Fittest”.
Is it involved by brain? How human brain can work with DNA in such a stabilized and rigorous manner?

Now a days, environment is rapidly changing. So, in a future, human might face a situation in which daily normal food is no more available and then a new type of food is sought nevertheless though DNA mutation for human to adapt to it is necessary.
Then new chemical substance will be developed, a kind of vaccination that can mutate DNA in a way that it can attain new function; “tolerant to a new type of food”.
Assuming that, in such a terrible era of food crisis, only available source of food is human droppings! Oh my god! Then special vaccination is developed ————-.
Can you eat it? Or else you choose the destiny of extinction?

Ok, let’s flee from such an extreme. DNA is learning it, means everyone is learning it. Therefore, By only evaluating an individual on the academic score or amount of income or family roots etc. can surely be of loss of possibility of the very survival of human being because nobody knows whose DNA can have it. Oh therefore, me myself maybe a special VIP for all human being like the fox in “The Little Prince” by Antoine de Saint-Exupéry. Or else, if DNA eventually becomes driving force for human discriminations,
I will stand against it. I think lactose tells us that being individual is human freedom. It has given a person what has been necessary respectively for a long period of time.