How humans are still evolving

[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.

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.

For sure genetic drift or mutations will continue to occur, but I just don't see it resulting in more or less babies produced any longer. There are so many other reasons people do or don't have kids that I doubt if any mutation is going to make a measurable difference. It isn't as though as a species we are disposed to produce as many young ones as possible unless something stops us .. well except for Khem maybe.

[The Grand Nudger]

It can also work the other way round.  Plague resistance is a great historic example.  People didn;t mutate that resistence in response to a specific plague, some portion of the population already -was- resistant when it hit.  

The adaptation didn;t lead to more babies...just more babies relative to all the dead non resistant portions of the population. Some of those adaptations may also have had the effect of increasing our lifespan by decades.

(If mine follow in my footsteps, in 40 years...I'll be father to 125 youngins......but I;d settle for 20..somebody has to put in the work if we;re gonna outbreed the morons. )

---

a less sinister example is red hair.  It;s difficult to see what advantage red hair gives..except for being pretty and making other people want to have your babies. Sure, sure, it;s a byproduct of something that used to be useful, but now we have fortified milk (and can drink milk!)...and yet it;s still a thing.

[brewer]

I like the high altitude scenario: https://en.wikipedia.org/wiki/High-altit..._in_humans

Hookin up with the Denisovans: https://en.wikipedia.org/wiki/Denisovan

[Catholic_Lady]

Interesting post, Mathilda.

[I_am_not_mafia]

Evolution is just another form of search technique. So when you refer to genetic drift or random mutations, what you are actually referring to is the part of search space that the genotypes currently occupy / could mutate into  as children climbing to a higher evolutionary fitness.

[Anomalocaris]

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.

For sure genetic drift or mutations will continue to occur, but I just don't see it resulting in more or less babies produced any longer.  There are so many other reasons people do or don't have kids that I doubt if any mutation is going to make a measurable difference.  It isn't as though as a species we are disposed to produce as many young ones as possible unless something stops us .. well except for Khem maybe.  

Yes, so many other factors do impact decision regarding how many babies are had. But genes continue to have an impact. If those other factors are random and completely non-genetic, then they will add a lot of noise, but will not cancel the effect of the genetic impact.

[BrianSoddingBoru4]

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

THANK you!!  As the redoubtable Lewis Black has observed, 'There's no soy milk because there's no soy titty!!'

Mind you, I don't object to these products in and of themselves (the almond and cashew versions are actually pretty good), it just frosts me that they're marketed as milk.  I get why they are, I just wish they weren't.

Lewis Black's further position is that these things are actually juices, but they aren't called that, because the very term 'soy juice' triggers a gag reflex.

Boru

[I_am_not_mafia]

There is also though a historical use of the word milk to refer to any liquid that has a milky look and feel. After all, Coconut milk has been called that for a very long term. Pretty sure it's been used for describing opium in the past. Maybe the noun milk should be considered as deriving from a description instead.

If so then it's actually historically consistent to refer to Soy milk as milk, even though it's not the same kind of milk as milk.

[BrianSoddingBoru4]

There is also though a historical use of the word milk to refer to any liquid that has a milky look and feel. After all, Coconut milk has been called that for a very long term. Pretty sure it's been used for describing opium in the past. Maybe the noun milk should be considered as deriving from a description instead.

If so then it's actually historically consistent to refer to Soy milk as milk, even though it's not the same kind of milk as milk.

Historical consistency has fuck all to do with accuracy.  If people had been referring to dolphins as daffodils for the last thousand years - all the while knowing good and goddam well that they aren't the same thing -  it would still be wrong to do so.  Same with milk.

Boru

[I_am_not_mafia]

There is also though a historical use of the word milk to refer to any liquid that has a milky look and feel. After all, Coconut milk has been called that for a very long term. Pretty sure it's been used for describing opium in the past. Maybe the noun milk should be considered as deriving from a description instead.

If so then it's actually historically consistent to refer to Soy milk as milk, even though it's not the same kind of milk as milk.

Historical consistency has fuck all to do with accuracy.  If people had been referring to dolphins as daffodils for the last thousand years - all the while knowing good and goddam well that they aren't the same thing -  it would still be wrong to do so.  Same with milk.

My point is that referring to something as soy milk is accurate because it is referring to its texture, not why it was produced. If 'milk' refers to an opaque white viscous liquid, then lactation is a milk as well as the juice from a coconut. Your analogy with daffodils and dolphins fails for this reason as one cannot be considered a superset of the other.

Context also matters. If you're referring to soy milk when talking to a biologist when talking about child rearing then it's not going to be accurate, but it is valid when shopping for a milky liquid. Basically it comes down to whether the term is useful or not. In the same way that chemists know that glass can be considered a liquid but no one will know what you are going on about if you refer to windows as vertical clear liquids.

And historical usage does have a major effect on how science talks about something. Significant work goes into making definitions less ambiguous. For example whether Pluto is a planet, what emotions are, what granite is etc.