Natural Selection and Human Beings

[Dreadsox]

I know many do not believe in the thought process behind evolution and natural selection.....and I do not want to debate it in this thread.

Currently I am taking a science course and the last few parts have been about genetics, natural selection, and evolution.

My thinking is this....

Have human beings for the most part, defeated natural selection?

If we have defeated it, have we in essence caused parts of our genetic code to be rendered useless? Defunct....but not elimiated it?

Does the elimination of Natural Selection have significant repercussions on the health of the human race?

Am I way out there this morning making no intelligent thoughts? A little knowledge is dangerous.

 

[Dreadsox]

Hypothesis:

At the moment any species stops evolving in response to challenges and threats, it risks extinction.

http://www.pbs.org/wgbh/evolution/survival/clock/

 

[Varitek]

Actually I saw an article recently about proof that humans are still evolving. Proof is hard to come by on big things, because it takes such a grand timeline to see things. But they found that a gene for lactose tolerance had independently evolved in several African communities, with the same function but different genetic location/makeup than the lactose tolerant gene for Europeans and their decendants. This was also cool because it was cited as an instance of evolution for social and not environmental reasons (cow milk being added to diets by human design, not natuaral design).

As for species ceasing to evolve, well, in addition to the fact that you can't know we have, I think there are ways around extinctions. Maybe humans have conquered the these challenges and threats in other ways, such as by the evolution of technology, medicine, etc. We have vaccinations to defeat diseases instead of part of the species dying off.

 

[Dreadsox]

We have vaccinations to defeat diseases instead of part of the species dying off.

Which my theory is causes us to have further problems down the road. We are artificially allowing DNA that would have been eliminated to continue to be spread.

The other thing I was thinking is you cannot stop evolution, but what will the effects be of say VIDEO games on our DNA code years from now.

 

[Vincent Vega]

There are two kinds of snakes in Australia that have changed over the past seventy years in order to eat the cane frog (or however it was called, a frog species from South America brought to Australia to keep control of insects that destroy the cane sugar in Queensland).
The frog is venomous and didn't have any natural enemies when it was brought to Australia. So it became a plaque and caused a lot of damage to the nature, but didn't help to secure the sugar cane. It just didn't do its job.
The one snake changed the form of its head, so it can eat the frog without getting poisoned. The other snake now has a longer body so that the poison doesn't harm that much because it disperses over a greater body area.

I would say every species still evolves, but normally it takes hundreds to thousands of years until there is significant change.
These two snakes were really interesting for scientists because they never thought evolution could happen that fast.

Also, the reason why Europeans can drink more alcohol, and don't become addicted that fast, compared to Indians, Africans, Aborigines or Asians is very simple.

In Asia fro example people learned thousands of years ago that you can sterilise water just by cooking it.
Europeans didn't learn to sterilise water that way, so they used alcohol until the late middle ages to sterilise water.
Because Asians substituted alcohol by water, there genes responsible for removing the alcohol out of the body, regressed, while Europeans still have this gene.

 

[A_Wanderer]

I know many do not believe in the thought process behind evolution and natural selection.....and I do not want to debate it in this thread.

Currently I am taking a science course and the last few parts have been about genetics, natural selection, and evolution.

My thinking is this....

Have human beings for the most part, defeated natural selection?

If we have defeated it, have we in essence caused parts of our genetic code to be rendered useless? Defunct....but not elimiated it?

Does the elimination of Natural Selection have significant repercussions on the health of the human race?

Am I way out there this morning making no intelligent thoughts? A little knowledge is dangerous.

Natural selection is the direct force of environmental factors upon a population. In this human beings have been masterful in buffering ourselves against the environment - our ability to manipulate our environment with higher intelligence and our morphological characteristics (for instance the opposable thumb) are the products of natural selection. Now humanity today experiences selection far more due to sexual selection, we select our mates for a number of reasons, the social controls certainly rank up there; we marry within our lot; and biological controls, those who have the genetic luck of being good looking will be positively selected for both in terms of mate choice and adventageously in life - if you look good you have a better job opportunities.

Natural selection may be removed from humans due to the homogenising effects of gene flow but sexual selection and in this new century artificial selection will be driving forces that may well accelerate our development far beyond the limits of gradual evolution.

 

[A_Wanderer]

I would say every species still evolves, but normally it takes hundreds to thousands of years until there is significant change.

The thing is that it doesn't, we do not see this gradual evolutionary chain in a lot of the fossil record - we do see such shifts with minor changes in some forms such as foraminifera tests in deep sea cores but for things like vertebrates we see prolonged morphological stasis (the palaeospecies stays the same) for millions of years sharply punctuated by the appearence of new species. This observation was explained by Eldredge and Gould as allopatric speciation (the fringe population seperated from the main population evolving and repopulating the area in a geological instant) being recorded as the sharp punctuations, the theory is punctuated equilibrium and the debate is quite interesting.

 

[A_Wanderer]

Hypothesis:

At the moment any species stops evolving in response to challenges and threats, it risks extinction.

http://www.pbs.org/wgbh/evolution/survival/clock/

Life at the edge of chaos, but it should also be noted that Van Valen found that the probability of a species becoming extinct remains constant for it's duration. The idea that all species must be locked in an evolutionary arms race of adaption does not match for things like relic taxa such as the coelocanth or lungfish which appeared hundreds of millions of years ago and have remained relatively unchanged because the ecological niche that they occupy (the specific environment where they outcompete competitors) hasn't seen a challenger to compete against.

 

[A_Wanderer]

As for useless DNA we don't even need to go down to gene level selection so see obsolete elements - from our appendix to coxix bone - vestigial elements that lack the function they initially had and get reduced but don't dissapear.

 

[Dreadsox]

As for useless DNA we don't even need to go down to gene level selection so see obsolete elements - from our appendix to coxix bone - vestigial elements that lack the function they initially had and get reduced but don't dissapear.

But isn't it the DNA code that produces adaptations? I wouldn't call it useless.

 

[verte76]

Gosh, how interesting!

 

[Dreadsox]

Wanderer? Why is DNA useless?

 

[Caroni]

Humans are still evolving and will be evolving for a long time, for example e professor told me that if you look to the fingertips of our ancestors you can see how they were big when compared to our fingertips now and that´s because humans do more stuff with fingertips like typing

 

[Caroni]

DNA is the least useless thing in the world!!!! DNA is in everything that´s alive!!!!!! it is so important that to have a DNA is a characteristic of live forms, if it doen´s have DNA then isn´t alive (until aliens proof wrong )

and mutations in DNA is what produce evolution (you can see it with bacteria in a faster rythym) and of course the adaptation to the environment and conditions

 

[randhail]

Actually, I think RNA is more important than DNA. DNA has a whole lot of useless crap that doesn't really do much tough. Once you sift through the crap of introns and you splice together some RNA and enter the wonderful world of proteins - that is where the party's at.

 

[A_Wanderer]

But isn't it the DNA code that produces adaptations? I wouldn't call it useless.

DNA is defintely the blueprint but changes in developmental pathways are also an important level of selection. The question of what is the unit of selection ranges from single genes all the way to whole populations and is a fascinating question. The introductory level examples of evolution do have a lot of exceptions that rather than disprove evolution reveal more complex interactions.

 

[A_Wanderer]

Humans are still evolving and will be evolving for a long time, for example e professor told me that if you look to the fingertips of our ancestors you can see how they were big when compared to our fingertips now and that´s because humans do more stuff with fingertips like typing

Thats like neo-lamarkism, I am not too sure what selective pressure on fingertips there is - it would be worthwhile quantifying.

 

[Varitek]

Which my theory is causes us to have further problems down the road. We are artificially allowing DNA that would have been eliminated to continue to be spread.

The other thing I was thinking is you cannot stop evolution, but what will the effects be of say VIDEO games on our DNA code years from now.

THat's an interesting theory about vaccinations. I honestly have no accademic expertiese on this, but maybe the evolution of medicine etc can supplant the evolution of the genome. And maybe it is doing damage. Maybe the people being allowed to survive will offer things to the race that are valuable in other ways and evolution wouldn't have originally valued - artistic ability or somehting? the evolution of evolution...


As for video games, that is sort of interesting, but I guess video games don't directly relate to survival as disease and ability to process food does. I'm sure scientists will keep an eye out for this as ti falls under what I mentioned before with lactose tollerence from socially introduced foods - it's the social sphere instead of natural sphere influencing evolution.

 

[Varitek]

Life at the edge of chaos, but it should also be noted that Van Valen found that the probability of a species becoming extinct remains constant for it's duration. The idea that all species must be locked in an evolutionary arms race of adaption does not match for things like relic taxa such as the coelocanth or lungfish which appeared hundreds of millions of years ago and have remained relatively unchanged because the ecological niche that they occupy (the specific environment where they outcompete competitors) hasn't seen a challenger to compete against.

But humans don't occupy an evolutionary niche - we interact with a variety of environments that keeps getting more expansive as technology pushes us to frontiers, and we interact with thousands of species (though we may not always seem to care). And now we interact with an artificial environment that is far from unchanging and we are effecting the atmosphere wtith polution, destabilizing our environment further. So, we are not a niche species, and I think Dread's question stands except for these exceptional (and really, really cool) species.

 

[A_Wanderer]

I think it's dangerous to make leaps such as "select for artistic ability" because many of these traits can actually decrease fecundity, for instance look at birth rates and intelligence. Im not saying that we will get dysgenics due to poverty creating Morlocks but when we look at 'positive traits' we must consider if they occur with enough frequency to have an effect on the population and if they will be selected for within the population. This is ignoring the genetic and environmental interactions that take place to shape behaviioural characters that effect reproductive success.

I see lactose tollerance as an environmental factor divorced from a social one, society doesn't will a biochemical pathways selection its still due to a material cause for material reasons. The crossover between biology and society exists because society is a direct product of our biology, cognition and communication are evolved characteristics in animals.

 

[A_Wanderer]

But humans don't occupy an evolutionary niche - we interact with a variety of environments that keeps getting more expansive as technology pushes us to frontiers, and we interact with thousands of species (though we may not always seem to care). And now we interact with an artificial environment that is far from unchanging and we are effecting the atmosphere wtith polution, destabilizing our environment further. So, we are not a niche species, and I think Dread's question stands except for these exceptional (and really, really cool) species.

The niche of the bipedal hominidon the African Savannah? Civilization has only existed for a few thousand years tops and it's only been since then we have only had dramatic effects on the environment for a few tens of thousands of years.

Extinction is a function of probability due to innumerable factors, the thing is that the longer a particular species exists the probability level goes down furthur and furthur. It isn't a function of ever evolving animals getting progressively better.

Food and survival are not an issue today, but to relate the pressure of society look at attractiveness, the traits across all cultures for attractiveness have direct correlations with fecundity; biology makes women with 0.7 waist to hip ratios sexy, why a good complexion is beautiful and handsome men have strong jawlines. Society isn't just picking these things out they are hard wired, the expression can of course be modifief by societal pressures.

 

[Dreadsox]

This is one of the most amazing things I have seen.

http://www.pbs.org/wgbh/evolution/library/01/3/quicktime/l_013_01_56.html

 

[anitram]

But isn't it the DNA code that produces adaptations? I wouldn't call it useless.

Large segments of DNA do not get translated into proteins. And even within the DNA which is translated, changes in the sequence most of the time don't lead to "adaptations" either. (Just because I don't want to be inaccurate - I'm talking about introns which are transcribed and then cleaved and exons which are transcribed and then translated.)

And if you want to be technical, it isn't DNA code that produces adaptations.

 

[Caroni]

I love this thread because I´m not still so convinced about evolution, we have a lot of proofs but I find it very unlikely, I don´t know why, I´m very open minded

 

[A_Wanderer]

Large segments of DNA do not get translated into proteins. And even within the DNA which is translated, changes in the sequence most of the time don't lead to "adaptations" either. (Just because I don't want to be inaccurate - I'm talking about introns which are transcribed and then cleaved and exons which are transcribed and then translated.)

And if you want to be technical, it isn't DNA code that produces adaptations.

Im reading a great book right now called The Origination of Organismal Form that deals with this issue in relation to evolution, how gene level analysis of adaptions gives to narrow a view for the macroevolutionary changes that have a lot more to do with developmental pathways, fascinating and very multidisciplinary.

 

[Caroni]

^ What´s your profession????

 

[anitram]

Im reading a great book right now called The Origination of Organismal Form that deals with this issue in relation to evolution, how gene level analysis of adaptions gives to narrow a view for the macroevolutionary changes that have a lot more to do with developmental pathways, fascinating and very multidisciplinary.

It's a great point, and often something that is overlooked.

It's really easy to think of adaptations as a byproduct of mutation but that is really a very narrow view as you stated. It goes to explain some things but you have to look at the pathway in question to consider the totality of the facts.

Sometimes I miss my old science life. Fascinating stuff.

 

[Angela Harlem]

Sometimes I miss my old science life. Fascinating stuff.

I'm all for reading textbooks for fun, and recommend it to anyone (who has the time). One day it will be trendy and 'cool'. Just you wait!

 

[Dreadsox]

And if you want to be technical, it isn't DNA code that produces adaptations.

Remember I teach elementary school....its about as technical as I get.

My understanding is that the adaptations, such as comoflage would come from the survival of the DNA code that produces that trait.

If I am understanding this wrong I am sorry.

 

[A_Wanderer]

^ What´s your profession????

I stack shelves at the local supermarket at night and early morning for 30 odd hours each week.

And by day and evening I am locked away in my room reading journals and books to become the best damn palaeontology honours student in 2008 (part of the reason for working, being able to support myself as a full time student) and get some high qualification in that field. I will just raise the point that for an academic job in that field you have to be up with molecular biology, geology, geochemistry and the latest evolutionary biology - theres just not as many jobs limited to taxonomy. But the opportunities for those that have the skill are there both in research and industry.