
Why almost all multicellular organisms begin life as a single cell - llambda
http://www.sciencedaily.com/releases/2011/12/111215141615.htm
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gwillen
I just skimmed this article, but it doesn't appear to make the interesting
point that came to my mind when reading it, which is: in a multicellular
organism, what the article calls a "cheater", we call a "cancer". A "cheater"
is just a cell which, despite its common origin, has mutated to compete with
the other cells instead of cooperate with them. And indeed, we see cells do
that; we also see adaptations -- the tumor suppressor genes -- specifically
designed to inhibit such cells.

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jessriedel
Isn't this kind of a confused presentation? (I'm talking about the popular
article, of course; I have no doubt the researchers know their stuff.) The
cells of multi-cellular organisms like whales and humans aren't just
cooperative, they are genetically _identical_ , which means their evolutionary
prospects are tied together. The DNA in a pancreas cell is the same DNA as in
a sperm cell, so it's "in the pancreas cell's interest" to help out the body.
(Really, the key idea is the evolution is a competition between the _bits_
stored in DNA, not the physical DNA itself.) And the root reason the cells of
multi-cellular organisms like whales and humans are identical is because of
sexual reproduction. So the key bottleneck isn't the one-ness of the one cell,
it's the genetic identical-ness.

Now, yes, once you say all that I guess you can say that the mutations in
animal cells leading to non-cooperative behavior (i.e. cancer) are evidence of
this 100-division limit. But the amoebae are qualitatively very different
since they aren't all genetically identical. It's really closer to the
cooperation between human * families* than human cells, isn't it?

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jacquesm
> The cells of multi-cellular organisms like whales and humans aren't just
> cooperative, they are genetically identical

[http://www.sciencedaily.com/releases/2009/07/090715131449.ht...](http://www.sciencedaily.com/releases/2009/07/090715131449.htm)

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civilian
The article didn't explain the genetic difference very well... can you provide
an explanation?

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pygy_
They found out that the pathogenic mutation was only present in vascular
tissue, but not in blood cells.

DNA replication errors occur all the time, even in multi-cellular organisms.
Some of them lead to cancer, but most of them are either lethal (for the
cell), or, most of the time, innocuous.

The most likely scenario for the abdominal aortic aneurism is the following: A
mutation can occur during organogenesis, in utero. The earlier it occurs, the
more cells will be affected. Said mutation can be initially benign, but become
problematic in the long run. If the mutation occurs after the differentiation
between fibroblasts and blood progenitor cells, only affecting the former, you
get the scenario described in the ScienceDaily article.

