Horizon - Have Humans Stopped Evolving?

[mosaix]

Quite an interesting program this week.

The presenter interviewed a series of professors with varying opinions. Two gave me food for thought.

One said the moment we started to insulate ourselves from the environment: tools, fire, clothing, shelter, medicine etc., then we were bound to slow the process of evolving as humans who would normally have died before child bearing age lived on and were able to pass on their genes to the next generation.

The second gave a more practical example of this. He took the presenter though a graveyard to look at grave stones. A high proportion of gravestones from the 18th and 19th century were for children who died before the age of three. His words:

"These children were the raw material that fed human evolution. Such gravestones today are rare. In Shakespeare's time only one in three births made it to the age of 21. In Darwin's time that was up to two in three, now 99% of children live to 21 years of age."

I can't help thinking that both these people were viewing the situation that pertains in developed countries and that the infant mortality rate is still high in some parts of the world.

 

[chrispenycate]

Infant mortality can only select for factors that cause infants to die. If an immunity to AIDS sprang up somewhere in Africa it would pretty soon be widespread, just as very few European kids died of measles, while it hit the unprepared Amerinds hard. That's evolution; the selection from a wide and diverse gene pool of a characteristic that tends to increase survival chances, not telekinetic powers or X-ray eyes.

So, what characteristic should we be trying to encourage, or even better eliminate? Something complex, like stupidity? Tooth decay? A tendency towards cancer? A particularly eugenic and - um, practical? society could use statistical analysis to sterilise high risk groups, arguing that morally, in the long run, they were preventing quantities of pain that was otherwise inevitable (no, I wouldn't like to live in such a society).

Despite the bipedal stance being a relatively recent and unsatisfactory adaptation, most of the knee/back problems develop after breeding age, so there is no biological reason for an improved hip joint. Furthermore, medical science has rendered it ever less survival critical that people be in top physical condition; is an Olympic athlete likely to have more children than a couch potato?

So, apart from at a biochemical level – being able to metabolise pollution and recover from infections – natural selection has ground to a halt planetwise. If we want it back it's either toughen up the environment and vastly increase mortality, or go onto artificial selection, weeding out gene groups that are known to give unpleasant results, and do this with massive populations, not just the very rich.

But keep a control group of unmodded (as in Heinlein's ¬ Beyond this horizon, was it?) in case lack of diversity leaves you vulnerable to some unforseen stimulus.

 

[J Riff]

I think rap music proves humans stopped evolving.

 

[ZombiezuRFER]

Humans have not stopped evolving, and will not stop until the species is ENTIRELY dead. Evolution is the introduction of genetic mutations, which by natural selection weed out bad mutations, to adapt a species to an environment. Desensitizing yourself to the environment is false, you are creating a new environment. Infant mortality rates don't impact evolution, but rather encourage it, to get whatever is causing the deaths to stop, but encouraging evolution only means changing the environment something was adapted to. It will never stop.

 

[Dave]

I didn't see the program, but I have read some reviews of it and I think there is a problem with the definitions of "evolution". Surely, evolution acts over a much longer period of time than the time frames being discussed? And also everyone seemed to be making different arguments.

I'd agree that "natural selection" among humans has paused. Not only are humans surviving who would have died before, but also there has been a huge 'melting pot' mixing of humans from all corners of the Earth. So, the genetic variation within our global population is now greater than it has ever been. Natural Selection needs genetic variation to work, but it also needs some limiting effects upon the survival or reproduction of the population. Those have largely been eliminated, despite a wide disparity between the developed and developing world.

However, artificial selection of the characteristics of children, medical intervention to allow older women to get pregnant, these may or may not increase genetic variety, I think you could argue both ways.

As for not evolving since we began to wear cloths and make fire, that is just wrong - we evolved and lost our body hair. Children who didn't die from the cold, were instead selected for some other characteristic such as disease resistance.

And natural selection has not gone away, we only need some global disaster for natural selection to act on the population again.

 

[TheEndIsNigh]

I didn't see the program, but I have read some reviews of it and I think there is a problem with the definitions of "evolution". Surely, evolution acts over a much longer period of time than the time frames being discussed? And also everyone seemed to be making different arguments.

I'd agree that "natural selection" among humans has paused. Not only are humans surviving who would have died before, but also there has been a huge 'melting pot' mixing of humans from all corners of the Earth. So, the genetic variation within our global population is now greater than it has ever been. Natural Selection needs genetic variation to work, but it also needs some limiting effects upon the survival or reproduction of the population. Those have largely been eliminated, despite a wide disparity between the developed and developing world.

However, artificial selection of the characteristics of children, medical intervention to allow older women to get pregnant, these may or may not increase genetic variety, I think you could argue both ways.

As for not evolving since we began to wear cloths and make fire, that is just wrong - we evolved and lost our body hair. Children who didn't die from the cold, were instead selected for some other characteristic such as disease resistance.

And natural selection has not gone away, we only need some global disaster for natural selection to act on the population again.

Not sure that is the case Dave.

As Chris pointed out if an AIDS immunity gene did develop in Africa it would quickly spread throughout the world. Using the grains of rice on a chess board argument it wouldn't take many generations.

There's also This :-

Truth In Science - The Peppered Moth

 

[J Riff]

The experiments must continue until we have the perfect template- a nine-foot basketball player weighing 400 lbs.
I don't see ants or moths getting any bigger. Let them change color all they like- they can't hide from the ultimate predator. Us. Muah.
Try and stop mammals from evolving, not even Dolphins are up to the challenge.
What else is evolving anyway? Anything besides bugs fighting for their lives?
Are Giraffes getting taller?
The virii are probably the ones to watch out for- they evolve fast.

 

[soulsinging]

I think rap music proves humans stopped evolving.

I'd say country music is the better example.

I actually think we're devolving in a lot of ways. The most intelligent, successful people have essentially stopped breeding, while the dregs of society have a half dozen kids each. The movie Idiocracy touches on this a bit. Here in America, smart people don't reproduce while the guests of Jerry Spring have tons of kids. Not only that, but there's an increasing worship of ignorance, against science or self awareness and reflection. We glorify imagined pasts. It's quite depressing.

 

[Vertigo]

I think the interesting thing about your comment, Soulsinging and indeed some of the stuff in the program is that I think we have largely stopped evloving by natural selection. Arguably it is still continuing in some of the developing world but even there society dictates we do as much as possible to protect our own, rather than just letting nature (in the form of some illness for example) take its course. And that by definition is actively working against the forces of natural selection.

However I would argue that we are still evolving and, indeed, that evolution is probably accelerating. Instead of natural selection, however, it is now a conscious activity which tends to work a little bit more efficiently. For example, as Soulsinging points out, successful career minded people typically decide to have fewer or no children, almost exactly the opposite of normal natural selection. In the future (irregardless of whether we think it ethical) we will do ever more genetic manipulation of our own genes and thus directly control our own evolution; possibly in more than one direction - some social groups may choose to evolve ever more athletic bodies, others ever more powerful brains etc. Maybe we might even get Neal Asher's type of thing with genetic adaptations giving us qualities taken from other animals.

Of course natural selection will step in big time in the event of a major pandemic or anything of that nature, but historically there have always been spurts of evolution after major catastrophes have left evolutionary vacuums.

 

[Dave]

Not sure that is the case Dave.

As Chris pointed out if an AIDS immunity gene did develop in Africa it would quickly spread throughout the world. Using the grains of rice on a chess board argument it wouldn't take many generations.

There's also This :-

Truth In Science - The Peppered Moth

I'm not exactly sure which part of what I said you thought wasn't the case, but I know about the Peppered Moth - any that were not camouflaged were eaten by birds. Since the Clean Air Acts of the 1950's the selection has worked in reverse.

I'm also not sure how an AIDS immunity gene would "spread around the world" unless the people who had it replaced people dying of AIDS around the world.

So, if you mean the part where I said it also needs some limiting effect on the population or on reproduction, then you need to have the "eaten by birds" or " dying of AIDS" part of the equation.

But did you know that ancestors of survivors of the Plague (as opposed to those who were just lucky not to catch it) have a natural immunity to AIDS. There was a another Horizon programme on this a few years ago. So, an AIDS immune gene does already exist and has not "spread around the world". Well it has, but it hasn't had any great impact. Without any kind of homophobic comment intended, the immunity has been isolated in American gays with British ancestry, and since they are less likely to have children it is less likely to be passed on from them to the next generation.

 

[J Riff]

I'd say country music is better. - Soulsinging 2011
It is , far, far better, as are all trad forms, thank you for noticing. ) Vastly, geometrically many times over... how much better? Abjectly. Course if you have a modern station tuned in it can be bad, like all pablum pop of today.
Signs o' musical devolution- rap, autotune, american idol.

 

[Parson]

I'd say country music is the better example.

I actually think we're devolving in a lot of ways. The most intelligent, successful people have essentially stopped breeding, while the dregs of society have a half dozen kids each. The movie Idiocracy touches on this a bit. Here in America, smart people don't reproduce while the guests of Jerry Spring have tons of kids. Not only that, but there's an increasing worship of ignorance, against science or self awareness and reflection. We glorify imagined pasts. It's quite depressing.

I will not grace that first comment with a remark, as I love Country Music. May I suggest W4 in Detroit?

I don't believe that there is any short range thing that proves that we are no longer evolving or not. But a lot of traits in animals are passed on because the female of the species prefers something. (Big Bull Seals, Peacocks with great plumage etc.) I would propose that if one group is growing you should look at the females. (the Parson is treading on dangerous water here.)

Seriously, the best short range thing to point at in humans which MIGHT look to be evolving is the increasing height. Here in the States where widespread malnutrition has never been too great a thing, people are continually getting taller. I am an avid follower of high school girls basketball here in Iowa. And I can say with absolute certainty that the girls playing basketball on the average are 2 inches taller than 30 years ago. (Note: girls basketball has been a major sport in Iowa since the 1920's)

 

[skeptical]

Evolution never stops. It can change direction, but not stop. And there is no such thing as devolution. It is just evolution in a different direction.

Humans, of course, are a special case, since our technology and our social systems permit individuals who would otherwise be selected out of the gene pool to live long and reproduce like crazy. This may increase the frequency of 'undesirable' genes, like those for stupidity, in the human gene pool.

We cannot see these evolutionary changes, since it takes many generations, and we are simply not around that long.

Personally, I think that this is a temporary situation. Within 100 years (plus or minus a decade or ten), humans will take control of our own evolution through the use of genetic engineering. Given the choice, what would-be parent would refuse to take the action that would ensure their offspring were intelligent, good looking, athletic, healthy and long lived?

 

[TheEndIsNigh]

Dave:

It was the :-

Surely, evolution acts over a much longer period of time than the time frames being discussed?

aspect that I was querying.

Your info on the plague vs AIDS is fascinating and something I was unaware of. You would have thought it would have been publicised more.

Americans should be forming queues at the ports to get their daughters inseminated by red bloodied Englishmen to ensure the American way of life and moms apple pie.


Skeptical: There are a few.

Deaf demand right to designer deaf children - Times Online

 

[skeptical]

End.

That is weird!
The minority of deaf parents who want to choose deaf children just shows how damn irrational people can be at times.

 

[K. Riehl]

I like the idea the Greg Bear proposed in Darwins Radio. That humans would start to develop the ability to sense and use chemical communication and become stable groups which maximize cooperation and minimize conflict.

Or we could see the rise of the Slan. ;-)

 

[Vertigo]

Seriously, the best short range thing to point at in humans which MIGHT look to be evolving is the increasing height. Here in the States where widespread malnutrition has never been too great a thing, people are continually getting taller. I am an avid follower of high school girls basketball here in Iowa. And I can say with absolute certainty that the girls playing basketball on the average are 2 inches taller than 30 years ago. (Note: girls basketball has been a major sport in Iowa since the 1920's)

Unforunately I didn't catch the whole of this program but I'm pretty sure there was one bit that surprised both me and the presenter when she was told that actually our evolutionary trend now appears to be towards shorter and fatter rahter than taller!

 

[thaddeus6th]

That's correct, Vertigo, but I think it's a dubious conclusion to draw.

The data for that was all from one town in America. I don't think you can use information from one settlement in the richest, fattest and arguably most individualistic and capitalist country in the world and then generalise to the entire species.

 

[Vertigo]

No I agree Thad which is why I was a bit hesitant but it certainly suggests it would be unwise to jump to any obvious conculsions. The whole evolutionary process is so complex and dependent upon so many apparently insignificant factors that I suspect it is almost impossible to predict!

 

[chrispenycate]

I was quite amazed at the speed with which evolution can advance, given a sufficiently high birth/death rate, and a major change in environment. Ten or twelve generations after moving from a silvatic to a domestic habitat, with an increased food supply (in this case mammalian blood, largely from the constructors of the huts and their children) bilateral symmetry became less important ( nowhere to fly, anyway) and the capability of producing more offspring became the leading measure for success. Thus it became energy efficient to reduce the DNA load, and with it adaptability and diversity. Within twenty generations they could no longer mate with their open-air ancestors, nor generally with groups from more distant huts, and could, by older definitions for which reproduction is considered to be the be-all and end-all of species limitations, be considered to cave speciated.

That would be five hundred years for humans; and yet Australian aborigines were isolated from contact with external human groups a lot longer than this, with no loss of reproductive compatibility, so it has to be a special case. Still, evolution of small populations is something that can be observed, not merely postulated.