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Zinjanthropos
Post  Post subject: Do the Body's Cells Evolve?  |  Posted: Thu Jan 12, 2017 3:36 pm
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They say cells in our body get replaced, possibly several times during a lifetime. I've read that this occurs with varying frequency to all areas of the body except the brain. My question is whether the cells of an animal evolve during a lifetime? If so, then could cancer cells be a product of evolution occurring within the body?

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M_Gabriela
Post  Post subject: Re: Do the Body's Cells Evolve?  |  Posted: Thu Jan 12, 2017 4:07 pm
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Are you using the word evolve as in "change for improvement" or just change? If it is the latter, then our cells can mutate due to many factors... being the result of those mutations very differently; they could be silent with no effect or they could cause diseases.

In regard to cancer, the accumulated mutations are hereditary (if they happen on gametes of course) so the offspring could develope cancer in advance.. This also happen with other genetic diseases...like Huntington's. But cancer disease is very broad...

I'm not sure about using the term evolve... but there are many theories about evolution, many of them take into account neutral mutations... other say that if our genetic pool is changing then it's evolving... which is true... because evolve means change.


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Zinjanthropos
Post  Post subject: Re: Do the Body's Cells Evolve?  |  Posted: Thu Jan 12, 2017 5:00 pm
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I was thinking along the lines of adapting to their environment. I was wondering with all the stuff our bodies can be exposed to, including self exposure to toxins etc., if adaptation via evolution takes place as cells are regenerated? Is the genetic makeup of our DNA the same through life, no slight changes?

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M_Gabriela
Post  Post subject: Re: Do the Body's Cells Evolve?  |  Posted: Thu Jan 12, 2017 5:16 pm
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It changes yes, because it mutates. But those mutations are likely to be silent....

Ahmmmm, there are of course mutations that produce adaptive traits. The typical case of certain groups in Africa and their resistance to Malaria
https://en.wikipedia.org/wiki/Human_gen ... to_malaria

There are other examples... that I don't remember right now.... but are easily found on the internet...

The first mutation (the one that causes the adaptive trait -or not, it could be neutral or negative-) must occur on the gametes so it can be inherited by the offspring... Once stablished on the person's genome, it's hereditary.


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Zinjanthropos
Post  Post subject: Re: Do the Body's Cells Evolve?  |  Posted: Thu Jan 12, 2017 5:42 pm
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Can an individual person take advantage of an adaptation should it ever occur within their own body or is it only passed on? People who seem to be totally immune to the effects of tobacco smoking well into their 80's & 90's, could one of their ancestors have benefitted from an adaptation that took place within their own body? I mean go from not immune to immune in the course of a lifetime.

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M_Gabriela
Post  Post subject: Re: Do the Body's Cells Evolve?  |  Posted: Thu Jan 12, 2017 6:01 pm
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Ahmmm may be.... because the mutation/s has/have to be on the gamete in order to the offspring inherit it.

So if this mutation only happens in sexual cells then the person probably won't be benefited... But if the mutation occurs in the embryo, all cells will have it, sexual and non sexual, so not only the person but its offspring will be benefitted.


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Lynx_Fox
Post  Post subject: Re: Do the Body's Cells Evolve?  |  Posted: Thu Jan 12, 2017 11:22 pm

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It's not clear whether the OP intended to use the term evolution, to simply mean changes to like cells as they continue to reproduce thorugh the lifespan of the organism without necessarily being passed on. In that form, there is lots of examples of changes from cancer, which is reproduction of cells and late expressing inherited characteristic (such as some muscular dystrophy) that ultimately kill the organism. On the broader scale, I thought it was established that a small percentage of epigenetic changes can be passed to the gametes and thus potential to pass lifetime changes from an environment to offspring?


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marnixR
Post  Post subject: Re: Do the Body's Cells Evolve?  |  Posted: Fri Jan 13, 2017 9:39 am
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it is a fact that body cells accumulate mutations as a person gets older, which makes the occurrence of cancer more likely - however, this is not evolution, which is something that happens when genetic information is transferred from one generation to the next

as has already been said, the Weismann barrier between germ cells and body cells means that only mutations in the ova and sperm cells are carried through - which in the case of older men may means malformed sperm (unlike egg cells, which are in a girl's body at birth, sperm cells reflect the age of the body in which they are created) which could be a source of mutation and possible evolution in the next generation

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Zinjanthropos
Post  Post subject: Re: Do the Body's Cells Evolve?  |  Posted: Fri Jan 13, 2017 3:20 pm
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marnixR wrote:
it is a fact that body cells accumulate mutations as a person gets older, which makes the occurrence of cancer more likely - however, this is not evolution, which is something that happens when genetic information is transferred from one generation to the next


Does that mean each new replacement body cell is not the next generation?

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Lynx_Fox
Post  Post subject: Re: Do the Body's Cells Evolve?  |  Posted: Fri Jan 13, 2017 3:45 pm

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marnixR wrote:
it is a fact that body cells accumulate mutations as a person gets older, which makes the occurrence of cancer more likely - however, this is not evolution, which is something that happens when genetic information is transferred from one generation to the next as has already been said, the Weismann barrier between germ cells and body cells means that only mutations in the ova and sperm cells are carried through - which in the case of older men may means malformed sperm (unlike egg cells, which are in a girl's body at birth, sperm cells reflect the age of the body in which they are created) which could be a source of mutation and possible evolution in the next generation


I think your opinion is a bit dated and reflects biology before the discovery of epigenetics. Transgenerational epigenetic inheritance is observed in many plants and some animals, though I don't think there is any good examples for humans as of yet.


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M_Gabriela
Post  Post subject: Re: Do the Body's Cells Evolve?  |  Posted: Fri Jan 13, 2017 4:16 pm
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Zinjanthropos wrote:
marnixR wrote:
it is a fact that body cells accumulate mutations as a person gets older, which makes the occurrence of cancer more likely - however, this is not evolution, which is something that happens when genetic information is transferred from one generation to the next


Does that mean each new replacement body cell is not the next generation?


??


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marnixR
Post  Post subject: Re: Do the Body's Cells Evolve?  |  Posted: Fri Jan 13, 2017 4:20 pm
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I'm aware of the transgenerational effects of epigenetics, but somehow I see their effects as exceptions to the rule - the essence of actual genetics rather than the epigenetics effects is imo the main driver behind evolution, otherwise Lamarckian evolution would be far more prominent when we look at the evolutionary record

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Zinjanthropos
Post  Post subject: Re: Do the Body's Cells Evolve?  |  Posted: Sat Jan 14, 2017 7:03 pm
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When the unicellular became the multicellular there must have been a proven evolutionary advantage in doing so, no? Once multicellular was established as a good survival trait then at some point did these organisms find their niche and not evolve genetically, at least not much? I'm thinking about the living fossils such as the coelacanth and Wollemi Pine that have not evolved what people might consider many significant changes to their structure over millions of years.

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marnixR
Post  Post subject: Re: Do the Body's Cells Evolve?  |  Posted: Sat Jan 14, 2017 8:13 pm
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as far as i understand it we should not confuse change in the genotype with the change in the phenotype
mutations are expected to happen at a fairly constant rate, but sometimes a small change in the genotype can lead to a large in the phenotype (e.g. compare us with chimps) and sometimes a virtually unchanged phenotype can hide a large accumulation of changes in the genotype

the only thing that as far as i'm aware made a difference with multicellular life is that now it's easier to see when changes in the phenotype happen, whereas with prokaryota a lot of the change may not be visible in the way they look, but may for instance have resulted in being able to handle different chemicals and food chains

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Lynx_Fox
Post  Post subject: Re: Do the Body's Cells Evolve?  |  Posted: Mon Jan 16, 2017 7:27 am

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marnixR wrote:
....but somehow I see their effects as exceptions to the rule - the essence of actual genetics rather than the epigenetics effects is imo the main driver behind evolution,


Agreed.

Important to note that the exceptions nevertheless are real--something biologist would have completely denied just a couple decades ago.


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Zinjanthropos
Post  Post subject: Re: Do the Body's Cells Evolve?  |  Posted: Mon Jan 16, 2017 3:49 pm
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The body's tissue and organs replace their cells at different rates. I've read where the frequency rate for colon cells for example is 2-4 days whereas bone can take up to 10 years. Is this a product of evolution or do cells maintain a steady rate at all times?

When the multicellular organisms came along, it wasn't because individual single celled bone organisms were hooking up with similar single cell colon life forms, was it? Something has had to happen, no? If I took all the different cell types in the human body is it not reasonable to assume they've evolved to where they are now? I guess I'm asking whether multicellular life is the product of the evolution of one cell versus some type of symbiotic relationship between evolving unicellular critters?

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marnixR
Post  Post subject: Re: Do the Body's Cells Evolve?  |  Posted: Mon Jan 16, 2017 5:15 pm
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the in between stage is thought to be something like Volvox, which is really identical cells sticking together
the next stage would have been sponges which are essentially choanocytes sticking together in a shape characteristic of the sponge species

subsequent stages of multicellularity would then involve specialisation into things like muscle, nerve, liver etc. cells
as far as I'm aware this type of specialised cell does not exist in isolation, i.e. in single-called organisms

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Lynx_Fox
Post  Post subject: Re: Do the Body's Cells Evolve?  |  Posted: Wed Jan 18, 2017 12:48 am

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Some protist, such as slime molds differentiate into different forms and functions when they group into colonies. I suppose similar organisms were probably more common as true multicellular life started.


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Zinjanthropos
Post  Post subject: Re: Do the Body's Cells Evolve?  |  Posted: Wed Jan 18, 2017 3:19 am
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The cells for vestigial organs, body parts etc? Have those cells evolved to be used elsewhere in the body or do they just disappear altogether in time?

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marnixR
Post  Post subject: Re: Do the Body's Cells Evolve?  |  Posted: Wed Jan 18, 2017 8:34 pm
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I'm not sure that vestigial organs are necessarily using different cell types than other organs
do you have any specific examples ?

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Zinjanthropos
Post  Post subject: Re: Do the Body's Cells Evolve?  |  Posted: Thu Jan 19, 2017 1:51 am
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marnixR wrote:
I'm not sure that vestigial organs are necessarily using different cell types than other organs
do you have any specific examples ?


I took this from Wiki re vestigial parts & organs. I was only wondering what is happening to the cells of vestigial body parts as far as evolution is concerned. Do they evolve to become some other feature, strengthen others or eventually disappear altogether?

The muscles of the ear, wisdom teeth, the appendix, the tail bone, body hair, and the semilunar fold in the corner of the eye.

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Zwirko
Post  Post subject: Re: Do the Body's Cells Evolve?  |  Posted: Thu Jan 19, 2017 11:52 am
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Zinjanthropos wrote:
My question is whether the cells of an animal evolve during a lifetime?


B-cell maturation is the best example.


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