Humans Disrupt Evolution

[cilpolir]

whoops sorry, i was talking about beer (which is bear in my language to make it more confusing )

[yamman13]

I'm actually taking an evolution module at uni atm. One of the ways Natural selection works is by the most successful genes being replicated more. This normally translates as Better genes-better chance of surviving(longer)-more offspring-more of the same gene.
However, in the most developed countries the populations are going down, people are having less and less kids.
In the third world, the poverty cycle results in familys having more and more kids, to help support them, and also due to mortality rates.
Im not suggesting that that people in developing countries have inferior genes, but one of the main ways of determining success in life is wealth, and generally the rule is the better off financially you are, the less likely you are to have kids.
So in conclusion, The more sucessful you are(wealth), the less likely you are to have your genes passed on.

Which royally fucks up natural selection.

[r-ID]

there is no more natural selection, humans control the environment, not the nature.

You are saying that natural selection is fucked up because developing countries population is growing faster? Clear your statements.

[sanddbox]

there is no more natural selection, humans control the environment, not the nature.

So? Natural selection doesn't mean nature - it means natural. It will favor those that best function in the environment they live in. In our case, intelligence, money, power, etc allow the most offspring and the least chance of dying.

[Vulpine]

there is no more natural selection

That's just asinine. The planet is not one giant, controlled eugenics experiment. Natural selection continues to occur everyday and in every nation, with every species.

[r-ID]

That's interesting.

First sentence from wikipedia.

Natural selection is the process by which certain heritable traits—those that make it more likely for an organism to survive and successfully reproduce —become more common in a population over successive generations.

http://www.livescience.com

Darwin's natural selection is the process by which nature rewards those individuals better adapted to their environments with survival and reproductive success. It works at the level of genes, sections of DNA that encode for proteins serve as the software of life.

Do you really think that intelligence, money, or power will help you to spread your gens? I do see the future, only the wealthiest, most intelligence people lives.

Actually, we are arguing about terms.
I would not call the process which is going now an "natural selection".

From one stand of view you can say that "natural selection is fucked up" or just naturally selected itself

[yamman13]

Firstly, I'm not trying to be hostile in the following message, I'm just very passionate about evolution.

Your two points were that humans don't follow natural selection, and that I need to clarify my issue about wealth affecting it.

Well, as for the first point:

there is no more natural selection, humans control the environment, not the nature.

As you said quoted...
"Darwin's natural selection is the process by which nature rewards those individuals better adapted to their environments with survival and reproductive success. "

Controlling the environment is just one way of becoming better adapted to it . Humans are not the only species to use this strategy. Taking termites as an example, they build structures complete with air conditioning to remove heat and Co2, farm mushrooms, and what's more the same species of termite will build different structures in different climates, for example in a rainforest heat dispersal is less of an issue than on the savannah, so the nests are built with less surface area. The key is its the same species of termite that alters it tactics to fit its environmental conditions.
With this is mind, I don't think anyone would suggest that termites aren't suspect to natural selection, and so humans are the exact same, we've just taken the concept to extremes.

So, natural selection is still in effect on humans, but it is different, here's why...

Forget about the whole developing/developed country, if it helps.

The measure of success in biological terms is amount of offspring produced-good genes directly affect this. The strongest, smartest, fittest are more successful.
The anthropological measure of success still results from good genes - in intelligence,physical strength, communication skills(which often result in accumulation of wealth) etc. However this doesn't directly correlate to more offspring, which is what disrupts natural selection.

This is the fundamental difference between us and the rest of the Biosphere. Good genes in other lifeforms results in more offspring-there is pretty much no exception.
Good genes in humans don't necessarily result in more offspring-we are more complicated than that. we've overcome the biological incentive to reproduce to a certain extent, with everything from contraception to more complicated concepts like quality of life.
Therefore the most successful humans don't necessarily have the most offspring, which means good genes don't get passed on as successfully. Just because we have the capability to reproduce doesn't mean we take advantage of it.


In conclusion, Natural selection still takes places on humans, as controlling the environment is another way of adapting to it. However, Successful humans aren't any more likely to reproduce, so good genes aren't more likely to be passed on, and this is uniquely human.

[r-ID]

Controlling the environment is just one way of becoming better adapted to it

Adapting and controlling are two different things. You don't have to adapt if you are controlling it.

The measure of success in biological terms is amount of offspring produced-good genes directly affect this. The strongest, smartest, fittest are more successful.

Natural selection doesn't say anything that stronger, faster or more intelligence survives/dominates, it states that most adopted to the current environment dominates/survives (Guess what? We do control the environment). A cockroach might be more adapted and to have better genes then let's say an elephant, an dolphin, an tiger.
But yes, sometimes it means strength or intelligence.

Good genes in humans don't necessarily result in more offspring

that opposes the natural selection theory, so which one of the following statements is true:
1) Natural selection no longer applies on human
2) Natural selection is not completely correct.
3) More intelligence and better living people are less adopted to the environment.

[acantho]

This is a very interesting topic and one I both like and know a lot about (Bsc in Zoology & PhD in Ecology) and have taught the basics to year 1 undergraduates.. Didnt expect to see it on here and I'm glad those believing in religion haven't jumped in with the creationist nonsense, sorry but in my opinion that's what it is - not meaning to offend anyone.

It is in a way correct to say that humans have stopped evolving but that is more to do with us now adapting our environment than having to adapt over time to a changing environment. Also as there are so many of us now ~6billion and growing exponentialy - frightening thought realy, we are not subject to any genetic bottle necks such that the gene pool would be greatly reduced and as such ther would be more of an opportunity for newly evolved genes to become fixed in the population. Also we do not have any geographical barriers to separate populations and thus restrict gene pools. There has been an interesting study on a group of Jews in the USA that due to religious and cultural beliefs marry within a very tight gene pool. They are more at risk of a certaain genetic disease that causes the death of children in some couples (depending on the couples shared alleles for the disease). This shows what can happen when a genetic bottle neck (in this case the restricted breading) occurs certain genes become more prevelant in the population - if these genes give those individuals an advantage e.g. increased reproduction, longer reproductive period then the gene would spread and become fixed. Genees conveying a disadvantage tend to not become fixed but can live on in populations.

Then look at sickle cell anemia - google it as there is a lot on this subject, but basically one set of alleles and you have a certain resistance to malaria, no alleles you have no resistance, two alleles you suffer from disease due to the bloods inability to transport O2 efficiently. So even though this gene is bad, with half the complement of it it is acctualy good none of the gene is bad so there is neither positive or negative selection for it. (Only in areas where malaria is prevelant).

A question you have to ask when you talk about evolution is what is a species ? How is it defined ?
The concept in use and probably the best is the Biological Species Concept; indivdiuals able to produce viable ofspring i.e. offspring that can in turn reproduce. Obviously they have to recognise each other as the same species - this is not as problem free as you might thing e.g. crickets as they get older may loose parts of the combs on their legs thus produce a different sounding "song" thus not being recognised as part of that species they no longer are able to attract a mate and reproduce.
It's all about gene flow, so if you look at some gulls on the Neast cost of America there is gene flow between them and other species ! around a ring right down to the mediteranian - this is due to mating between not fully speciated morphs which overlap in their habitat, but take birds from both far ends of the ring and they wont be able to breed let alone produce viable offspring - but ther is still gene flow between them ! Have a google and read up on ring species - very interesting topic when you are considering evolution.

This realy is a big big big topic and I dont want to turn in to a bore or write an essay long post, I would suggest as a very good read on the subject of evolution a book by Mark Ridley called (funnily enough) Evolution. It is an undergraduate text book but very readable to the non-zoologists/biologists this should be it's location on google books (limited preview) http://books.google.co.uk/books?id=HCh7 ... &q&f=false

[chimchamcharu]

Interestingly enough, brain size is on the decline right now and has been for a couple hundred years. I don't think we're getting stupider but I think our bodies are realizing, "Hey, I don't use half of my brain anyways, why eat extra food to support it when it could just get smaller."

I'm not sure that's why.

Evolution almost always produces physical traits. This is because, in the animal kingdom, the strongest and fastest survive. Intelligence doesn't really have much to do with it. It can be argued that an ape with a sharp stick will win a fight with an ape without one, but on the grand scale, raw physical power wins.

Compare this with humans. Technology has done amazing things for us. We take in (on average) more information in a single day than most people 100 years ago took in each decade! Sure, this improves our quality of life (arguably), but evolution doesn't care. At the end of the day, the football star has a better chance of survival than most nerds/geeks.

So to sum it up, our brains are not shrinking due to "lack of use" necessarily, but rather because evolution favors strength.
.

Wouldn't it be more preferable to have someone that is very intelligent and strong? I think it would almost be preferable to have a semi-small person who can climb, run, dodge, jump etc. instead of a large mass who is brute force and not much else. Thinking almost favors the "quick" person due to the fact of how fast they have to think to dodge/run/climb.