Why did some branches of the human race become lactose tolerant?

[Blobbenstein]

I haven't read much about this,but I think that a few thousands of years ago that Europeans(as an example) started using animals for their milk.
This allowed the people of the time to have dairy foods through the winters when there may not have been much else food.
It must have conferred a real survival advantage to be lactose tolerant, I mean if that branch of humans evolved tolerance, then that must have meant that to intolerant lead to death or an inability to reproduce successfully.
It's humorous to say how weird it is to consume dairy, and for our ancestors to have started, but it must have made the difference between life and death at times through human history.
I suppose that cheese keeps quite well as a food for lean times.

 

[SummerRain]

The way I've always understood it, is that europeans developed tolerance to lactose because they were drinking milk (not that they could drink milk because they had a tolerance in the first place). But I don't know if that's just bad science that you hear or true. I looked it up a bit:

Here is an article from science direct about lactose intolerance.

"The implication is that harsh climates and dangerous diseases negatively impact dairy herding and geographically restrict the availability of milk, and that humans have physiologically adapted to that," said evolutionary biologist Paul Sherman, a professor of neurobiology and behavior at Cornell. "This is a spectacular case of how cultural evolution -- in this case, the domestication of cattle -- has guided our biological evolution."

And here is an interesting website (I think from a university) about evolution and lactose tolerance, which I enjoyed. There's some details for more reading at the bottom.

So the jist seems to be that in order for lactose tolerance to be an advantage, you first need to be farming dairy, and then genetic mutations that allow you to digest milk become an advantage and developed.

 

[Blobbenstein]

The first dairy consumers must have really needed the nutrients that milk gave if they were consuming it while lactose intolerant, and then the people with the first mutations must have had a big advantage over the ones who didn't, for that mutation to become more common.
These people obviously didn't start consuming it on a whim and just for fun, the way people now consume it.

 

[SummerRain]

Yeah I thought that, they must have put up with upset stomachs/etc for generations (I presume). I guess that was better than starving through the winter months when food was sparse. Perhaps they didn't know it was the dairy, that kinda thing might have been more common anyway... I don't know, definitely not my expertise, it's an interesting topic though.

 

[Second Summer]

I thought maybe anyone who stopped drinking animal milks would become intolerant after a while?

So I wonder if you start drinking cow milk as a baby while you're still getting breast milk, if you will just stay tolerant?

Sorry, haven't read the articles SR linked to.

 

[ledboots]

I thought maybe anyone who stopped drinking animal milks would become intolerant after a while?

So I wonder if you start drinking cow milk as a baby while you're still getting breast milk, if you will just stay tolerant?

Sorry, haven't read the articles SR linked to.

Many infants are lactose intolerant from birth, especially those of Asian/and or African descent.

 

[Second Summer]

Many infants are lactose intolerant from birth, especially those of Asian/and or African descent.

But there is lactose in human breast milk as well, right? Surely they can't be intolerant of that? Well, I suppose they can, but back in the day, that wouldn't have been the kind of genes that would live to be passed on.

 

[SummerRain]

Most babies are born able to digest milk, but only some people have a mutation in their genes that enables that to continue into adulthood. It seems like it's a genetic mutation, so a cross-generational change, not something that happens within a lifetime.

From what I read online (here is the NHS page on lactose intolerance) I don't think not eating dairy can make you intolerant - your body keeps producing the enzyme to digest milk whether or not you eat it.

 

[Amy SF]

Most babies are born able to digest milk, but only some people have a mutation in their genes that enables that to continue into adulthood. It seems like it's a genetic mutation, so a cross-generational change, not something that happens within a lifetime.

From what I read online (here is the NHS page on lactose intolerance) I don't think not eating dairy can make you intolerant - your body keeps producing the enzyme to digest milk whether or not you eat it.

I've read that if you're lactose intolerant, you can build up a tolerance to dairy by consuming it in very small amounts and then gradually increasing the amount you consume over time. I have no idea whether that really works or not.

 

[ledboots]

But there is lactose in human breast milk as well, right? Surely they can't be intolerant of that? Well, I suppose they can, but back in the day, that wouldn't have been the kind of genes that would live to be passed on.

I guess I shouldn't say "lactose intolerant" for newborns, but it is not uncommon for newborns to be unable to tolerate the animal milk based "formula" right from the first day of life. They projectile vomit and are miserably uncomfortable.

 

[Calliegirl]

This subject always reminds me of a story I heard long ago in a Native American history class. I don't know if it's true.

An Indian Chief (don't remember the name) wasn't feeling well and a white doctor came out to see him. The doctor examined him and told him he needed to drink more milk. The Chief looked at him shocked, then began to laugh. He pointed at some women who were nursing their babies and asked which one he should get it from.

Native Americans did not drink milk as adults or from other species, and they have a high rate of lactose intolerance.

There's an interesting chart at this site.
http://anthro.palomar.edu/adapt/adapt_5.htm

 

[das_nut]

It's humorous to say how weird it is to consume dairy, and for our ancestors to have started, but it must have made the difference between life and death at times through human history.

Have you read about some traditional foods? It's very clear that our ancestors weren't food secure. Look at how they had recipes for all parts of an animal - it's not that people were in tune with nature and not wasteful, it's that people had a good chance of starving.