
DNA studies topple the ladder of complexity - dnetesn
http://nautil.us/issue/9/time/evolution-youre-drunk?utm_source=tss&utm_medium=desktop&utm_campaign=linkfrom_feature
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fchollet
There seems to be some confusion between complexity, quantity of DNA, and
intelligence as a measure of organism complexity.

A larger quantity of DNA does not translate into a more "complex" organism, as
amoebas prove. In fact, I would think it likely that organisms with a very
large codebase have to be very simple ones, since the simpler an organism is
the "safer" it is to add useless DNA code to it without breaking anything
essential.

And consider intelligence: it is generally thought that the human brain is
largely self-similar (the same structures can be observed throughout the
cortex, repeated in layers and columns) and therefore very _simple_ from an
information-theoretic point of view. You could express what it does using very
little information, or code. The closest we have to an artificial visual
cortex, deep convolutional neural networks (shown to have a representational
power equivalent to the primate visual cortex [1]), can be implemented in just
a couple hundred lines of CUDA code. Just because a system is hard to
understand does not mean it has to be complicated, or that it requires a lot
of code (DNA or otherwise) to implement.

[1] [http://arxiv.org/abs/1406.3284](http://arxiv.org/abs/1406.3284)

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crimsonalucard
Just because you have a simple UI doesn't mean the code underneath isn't
complex.

Technically, you can have source code that's mind boggling bloated and complex
for something as simple as doing addition.

In the end, the selection mechanism that evolution uses for natural selection
is just survivability. Bloated, ugly code doesn't affect survivability if it
all ends up working correctly.

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snowwrestler
The assumption behind this story doesn't make sense to me. If you look at
amoeba today and a human today, they are at the same "depth" on the
evolutionary tree, just on different branches. Mammals have been evolving for
tens of millions of years...but amoebas have _also_ been evolving during that
time.

If we could go back a couple hundred million years and compare an amoeba from
then, to a human from now, I think we would see that the older organism is
less complex. But we can't do that, and I don't see how looking at a modern
amoeba is any kind of reliable proxy for that.

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henrikschroder
> Furthermore, the idea that complex parts like a brain and nervous
> system—including nerve cells, synapses, and neurotransmitter molecules—could
> evolve separately multiple times perplexes evolutionary biologists

This makes absolutely no sense. Why would this be perplexing? If evolutionary
pressure causes a feature to evolve once in one part of the tree of life, why
couldn't it happen multiple times independently? It would be a lot more
surprising if it didn't!

~~~
pbhjpbhj
> _If evolutionary pressure causes a feature to evolve once in one part of the
> tree of life, why couldn 't it happen multiple times independently?_ //

Isn't it rather that the features work in the same way. Bats and dolphins [1]
using echolocation that - I've heard - works the same way but the pressures on
them are different, the environments different. Given the random occurrence of
mutations it seems striking (to me) that these similar paths should be
followed.

A corollary would appear to be also that if parallel evolution can converge on
identical structures that reliance on morphological features to indicate
common ancestry is flawed. If evolution tends to converge then a geological
sample with a simple form of fossil can't be assumed to be contemporaneous
with another sample, the fossils could be the result of parallel evolution.

I've never understood why mainstream paleo-biology seems to reject that life
could have started in more than one place. Convergent evolution suggests that
the same types of complex structures can develop independently too.

Perhaps Star Trek's universe of four-limbed, bipedal, binocular aliens isn't
so far-fetched after all!?!

\---

[1]
[http://www.nature.com/nature/journal/v502/n7470/full/nature1...](http://www.nature.com/nature/journal/v502/n7470/full/nature12511.html)

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fasteo
And then, you need to add another dimension: 5% to 8% of our DNA in from
viruses that once infected us [1]

[1] [http://phenomena.nationalgeographic.com/2015/02/01/our-
inner...](http://phenomena.nationalgeographic.com/2015/02/01/our-inner-
viruses-forty-million-years-in-the-making/)

~~~
otakucode
And do you qualify those viruses as alive? Why do we have more claim to the
tangle of DNA in our cells than they do? Why do we not simply qualify as
vehicles evolved by the virus to accomplish its travel through the centuries
of reproduction? Obviously, we very well might.

Perspective is, at best, meaningless, and, more often, misleading. The view
that the evolution of oxygen-bearing organisms was a boon which unfurled the
history of organisms which resulted in us is exactly equivalent to the view
that the evolution of oxygen-bearing organisms caused the most calamitous
tragedy in the history of the planet, wiping out nearly a whole planet of life
and dooming the future to a lack of complex anaerobic organisms.

Objectivity and a dispassionate approach to knowledge isn't just a personality
affect of scientists. It's a vital tool.

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jostmey
When I first looked at the genetic code, my first question was where is the
code? The letter sequences and arrangement of genes looked random. Gradually I
started to realize that the genetic code _is random_ , and that the design of
an organism is _irrational_. After having this personal realization, biology
finally started to make sense.

~~~
henrikschroder
[http://en.wikipedia.org/wiki/Protein_biosynthesis](http://en.wikipedia.org/wiki/Protein_biosynthesis)

The order of amino acids that make up specific proteins are neither random nor
irrational, and that's just one example of things that our DNA explicitly
encodes.

