How humans are still evolving

[I_am_not_mafia]

Yes, humans are still evolving. Here's how you can tell.

Examples given how the grandmother effect might be making Alzheimer's less common. Why Dutchmen are growing taller faster than other countries. And what's particularly interesting to me is how we should all be lactose intolerant.

Humans mostly shouldn’t be able to drink milk past infancy—the majority of adults today can’t really digest it. When we’re babies, the gene that encodes an enzyme called lactase is turned on, so lactase is around to digest lactose (one of the principal components in milk). As we get older, the lactase gene is supposed to turn off. But several thousand years ago, being able to drink milk without getting sick became an advantage in some parts of the world. We’re not exactly sure why, though it probably has something to do with its nutritional value and wide availability on farms. Some evidence suggests that Europeans made cheese for some 4,000 years before any of them developed the ability to properly digest lactose. A few lucky individuals happened to acquire a mutation in the lactase gene that allowed it to stay turned on, even after infancy, and therefore allowed them to rely more heavily on dairy later in life.

I've always eaten lots of cheese and drank milk. But on reaching my 40's I became increasingly intolerant to it. I ended up having a serious cold at least once a week which would completely floor me. It also gave me MS. I now know that it's because of milk because I was lax about checking the ingredients in the vegetable soups I bought in a cafe I've started visiting and had a flare up as a result. The molecular mimicry idea of MS is one of the leading theories for its cause. Namely that a protein that is found in milk is similar to that which makes up the myelin sheath covering nerves. The immune system learns to recognise this protein as a foreign invader and starts to remove it wherever it is found.

The lactase gene is supposed to turn off after the baby no longer needs to be breast fed. So perhaps with people with MS it's still being turned off but much later in life. If so then it suggests that eventually MS will eventually be evolved out of the population, assuming that we are still relying on dairy for our needs and there is a single cause of MS.

Milk is one of these things which seems so innocuous because of how ubiquitous it is. But it's actually quite nasty stuff when you consider its long term costs, both in terms of health (autoimmune diseases, saturated fats) and on the environment.

[Silver]

I stopped drinking dairy milk a long time ago when I discovered soy and almond milk.

[I_am_not_mafia]

I stopped drinking milk a long time ago when I discovered soy and almond milk.

I don't miss milk at all now. The alternatives to milk are just as good in my opinion. I'm addicted to Alpro deserts.

[ignoramus]

I did NOT have a lovely strawberry milkshake at my favourite gourmet hipster coffee food place last Sunday!

[LastPoet]

I stopped drinking dairy milk a long time ago when I discovered soy and almond milk.

Those are not milk. Milk is what mammals produce for their younglings. Those are almond and soy juices.

- your friendly hair spplitter

[robvalue]

Once I stopped drinking milk I realized how bizarre it is to drink milk intended not only for the young, but for the young of another species.

Interesting stuff! Why do we need to evolve though? I thought we Won Teh Earth!

[Whateverist]

If lactose tolerance was developed in the last several hundred years I can see how it could have been selected for. But today I don't see how any advantageous mutation will ever be selected for or, for that matter, how any reappearance of a less favorable form will ever be selected against. Thank you modern medicine.

[The Grand Nudger]

Dairy and grain adaptations are fairly recent, on evolutionary timescales, but older than a few hundred years.  They evolved directly alongside domestication and agriculture.

Mutations will be selected for today just as they've always been. It can be as simple as the ladies liking whatever it is. It;s true that medicine can reduce this or that pressure..but it can also accentuate another. Hell, the efficacy of a particularly dominant form of medicine can -be- a selective pressure.

[Clueless Morgan]

If lactose tolerance was developed in the last several hundred years I can see how it could have been selected for.  But today I don't see how any advantageous mutation will ever be selected for or, for that matter, how any reappearance of a less favorable form will ever be selected against.  Thank you modern medicine.

Evolution doesn't only work by actively selecting for or against mutations though. Evolution also works by genetic drift that can appear to have no current advantage or disadvantage but can develop an advantage or disadvantage in the future.

I'm thinking of an example I read in Dawkins' The Greatest Show on Earth where biologists were doing research on the evolution of bacteria and they discovered that a certain strain of the bacteria developed a mutation in generation M, let's say, that didn't become advantageous to the bacteria until it developed a second mutation in another gene in generation, let's say, X. There was no active selection of genes going on in the bacteria, it all happened by genetic drift in genes that either weren't being expressed or didn't disadvantage the bacteria to the point where it couldn't continue to reproduce and thrive.

Such genetic drift can be occurring right now in humans that we don't know about yet and therefore cannot actively select for or against.

[brewer]

I stopped drinking milk a long time ago when I discovered soy and almond milk.

I don't miss milk at all now. The alternatives to milk are just as good in my opinion. I'm addicted to Alpro deserts.

Glad you stuck an "r" in there or I was going to be concerned. You might have devolved.