h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Taking some of the points out of the Sept 11th thread I was wondering on the communities opinions on the following. Assumptions made are that some form of survival of the fittest evolution is in progress and that mankind evolves:-

As we get more medically and socially advanced (or what we see as being that) so the average lifespan increases. So also we eradiicate or find cures for otherwise lethal illnesses or conditions.
This means that more and more people get to survive thus undermining the workings of natural selection, which would have removed them without mankinds interference.
Now my personal leanings are that this is generally a good thing, especially for the individual .
however, as a species (or whatever Homo Sapiens is) maybe this is not such a good thing since many mutations will survive to pass on their genetic code when at other times they would not have done so.

So, basically, given the assumption at the top, are we heading towards making the human race redundant. Or, as that is a little strong, are we opening up more trouble for ourselves as the mutations mutate and come up with ever more challenging medical problems?
Equally, if we are so diverse, and with many mutations not fitting with the environment we are in except by artificial means, then will we no longer be the 'fittest' animal for our niche and thus open up an evolutiion opportunity for another animal to evolve into, perhaps out evolving us over time for the same niche?

On the other hand, is this to our advantage in that the human race will have many, many mutations within a generation so that if a catastrophe does happen to the human race, or heaven forbid we get our act together and go off exploring the universe, then we have a much larger genetic pool and therefore, as a race, have a much larger chance of surviving a catastrophe or in new alien environments?

Equally, are we mature enough ytet as a society to understand and deal with the outcome of our actions in this area? My personal feeling is definitely not.

Hopefully I have managed to make that as theoretical as possible and high level. Hopefully everyone realises this is not about going round killing anyone you don;t like the look of.

Actually, that's another isde of this. In certain human environments, or societies, brawn is more important than brain. If you are violent, or physically powerful you get to suceed. Whereas a skinny wannabe intellectual (like me ) wouldn;t last 5 minutes. Is there a chance of us ending up as a 2 tier society here?

Evolution is simply adaption to an enviroment. By adding technology, including medical technology we simply change the enviroment so instead of adapting for toughness or resitance to disease we instead adapt for easier use of technology and so on.

Of whether we are evolving in the direction we want to is still up in the air...

The human race is not genetically diverse. A typical chimpanzee band of around 50-60 animals is more genetically diverse than the *entire* human race. Evolution works slowly, and we haven't been around very long.

If, as seems possible, the human population crashes sometime in the next couple of centuries, natural selection will have ample opportunity to redress any accumalation of genetically based, but medically treatable, conditions.

Noggin

Don't forget that, in the main, technology/medical advancements are mainly responsible for increasing our life expectancy in terms of us spending more time being very* old. As most people when older don't have children, their (could be termed 'artifical') prolongued existance as a result of technology/medical advances, won't affect the gene pool, as their genes will have already (if they have reproduced), been passed on. This is why, say, a gene that makes you drop dead on the day of your sixtheeth birthday wouldn't get 'removed' from a population of interbreading humans, unless it had a detrimental affect on an individual during, or before their reproductive age/time. tink that kind of makes sense

16 is not before reproductive age?

It seems you have accepted two ideas without debate:

1. The use of technology to extend human life (or for any other purpose) is not in and of itself a natural evolution.

2. Mutations, by surviving, better the chances of surviving.

Recent research is beginning to suggest that mutations sometimes just happen, and as long as they don't hurt the chances of survival they are likely to proliferate. They may even proliferate if they don't hurt *too much*. If this is true, than the fact that mutations that spread within the human population that would not "normally" survive cannot be said to be truly harmful, since mutations are in most cases neither beneficial nor harmful. They're just different. Survival with a "harmful" mutation is not undermining natural selection.

But the first point is the more important one. There always seems to be an assumption that human beings are "above" nature in some way, and that technology is the prime example of this - anything technological is not natural. But if you think about it, humans are perfectly natural and apart from our constant self-delusion that we are somehow better than the average ape there is no evidence that we are in any way better than even the average cabbage. Certainly smarter, but not better. Humans cannot escape their animal nature, and by extension everything we do is natural. A worm changes its environment by turning compost into humus, we change our environment by turning iron ore into steel. Our swallowing penicillin tablets is no different from a monarch butterfly ingesting compounds that are poisonous or distasteful to predators.It's more complex (and smarter) but no better, and no worse.

Noggin, this lack of diversity seems a bit strange. Wasn't there a postulated population crash back sometime in our early history where they reckon that we were reduced to a population of a a couple of thousand only?

And as for the likely hood of a pop crash in the next 100 years, what is the reasoning behind this thinking and what cause is proposed?

I might be wrong, but I thought that mutations normally come to dominate a population by being better able to resist a disaster or massively adverse conditions, such as a disease perhaps, or a volcanic event, that takes out all the less fortunate. Or are there other mechanisms? Am I being to simplistic?

Anyway to continue my thought: given that medical advances and technological improvements almost guarantee our survival into adulthood, what we must be left with are lots of mutations, none of which confer any great advantages over each other. Evolutionary speaking, the handsome A-student football champion from the rich background is no better off than a deprived kid from the ghetto who never got past primary school. Both have as good a chance of procreating, and evolutionary speaking they are equal.

So, what we are left with now is a gigantic pool of people, with a large number mutations around, many of them probably very subtle. This could be good, in that if a disease did ever come about, at least some might be genetically coded to survive such a disaster. It might also be bad, because the human race is still very young, and despite our huge numbers, our genetic diversity might be too small to survive a major onslaught, and we might all be taken out.

Woodpigeon

What if evolution wasn't a continuous process but happened in almost discrete steps interspersed with long periods of not much change?
What if we're in one of those periods where not a lot is happening in evolutionary terms. I don't think the advances cited (medicines, technology etc) have evolutionary advantage at the moment but given that evolution works over slow (generations) timescales then who knows what might happen in the future.

Ictoan - the relative lack of diversity is mainly because humans haven't been around long. "Mitochondrial Eve" is estimated to have lived only 150,000 years ago, and "y chromosome Adam" about 250,000 years ago. A short period in evolutionary terms.

In addition, as you mention, it is now believed that humans only just survived the eruption of a supervolcano (the name is on the tip of my tongue, but evades me for the moment - one of the penalties of age ).

As for population crashes, I may be being unduly pessimistic, but in general increaing ecological fragility gives plenty of scope - particularly in regard to disease and climate change. Or possibly even another supervolcano - Yellowstone perhaps.

Noggin

Toba. That was the name. And I meant to say it was about 80,000 years ago.

Noggin

80,000 years and you still remember the name? And I forget names 5 minutes after I meet people.

Woodpigeon, the way you describe it is the prevailing theory, but there is some more complexity. A couple weeks back I was reading an article in the NY Times about research that suggests evolutionary mutations that increase in the population do not necessarily contribute to survival. Their is a strong factor of chance. The article was subtitled "Evolving by Accident, Not Fitness" but unfortunately to view it online requires payment, and the article was too brief to be worth the money. It dealt with frogs that had a call that clearly attracted predators, and ironically the frogs with the best calls were more likely to be eaten and more attractive to females.

So an increase in the population of traits that do not contribute to survival is not necessarily bad, and not necessarily the result of technological advances. That kind of thing happens naturally anyway.

Phil, Richard Dawkins writes about "evolutionary stable states" that are exactly what you describe - long periods when not much happens to change a population.

I think we are saying the same thing - there are mutations which are bad, good and neutral. Many of the bad ones are not bad enough to prevent the adult with them from procreating, so they keep getting passed on; many of the good ones do not confer any real evolutionary advantage on the carrier because we are monogamous (by and large) and society does not and cannot really impose any strictures on sexual practice between consenting adults, and many of the neutral ones get through by default. However there are probably a few neutral ones that at some time, might just be the right mutation for the right event, and make the difference between survival and extinction.

Just a thought. Don't know whether it makes sense or not.

Woodpigeon

d'E, Gould and Eldridge called it Punctuated Equilibria and it is born out in what is known of the fosil record.

The fact that many people with an genetic disease can survive into adulthood and become parents, means that their must be an larger vairation in the gene pool these days. As we don't know what the cause of the next evolutionary bottleneck is going to be surely a large variation in the gene pool will increase our chances of survining it?

Well, you can argue both, I guess. The big drawback is that as a species we are far too young, and we share very similar DNA. Even so, we might be lucky. The 1918 flu killed millions around the world, but others were strangely unaffected, even though they were exposed to the disease like everyone else. They possibly had a genetic resistance to it.

Interesting stuff. One of the things that prompted this was the reports (I don't know how truthful) of women in africa who appear to be resistant to AIDS. Never saw any follow up.

Presumably the usefulness or otherwise can only be judged against current environment. For example there may be a so far neutral mutation in a large proportion of the population which suddenly becomes a liability or a survival guaruntor when the human race encoutners a new disease.

So, Should we be monitoring the situation? Perhaps there are individuals or communities out there with beneficial mutations which could in some way help thos ein another community? Ie the mutation didn't turn up where it was most needed?

I believe the report you're refering to is of several African prositutes who were not becoming infected with the HIV virus despite being exposed to it on a regular basis. I believe that the reason for this was not genetic but rather that their immune systems was responding in such as way that they were not becoming infected.

I was told by a lecturer who is a consultant in HIV/AIDS medicine that when they went back to work after they helped in teh study all the prostitutes did in fact become infected with HIV.

It looks like this was another false hope in the fight against HIV,

Here's the URL of the report - http://www.jci.org/cgi/content/abstract/102/9/1758?ijkey=e351d681d04c7a54468b169e421bf4052c24825c&keytype2=tf_ipsecsha

And here's a url of the report about how they got infected.

http://www.jci.org/cgi/content/full/107/3/341

I'm on a hosiptal trust computer, so they might have a isp address that signels that the hospital is subscribed to the journal, or it might be free to access, eitehr way I'm not sure.