
The Very First Animal Appeared Amid an Explosion of DNA - montrose
https://www.nytimes.com/2018/05/04/science/first-animal-genes-evolution.html
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chiefalchemist
"Humans and sharks, for example, make hemoglobin using nearly identical genes.
That means hemoglobin genes were already present in their common ancestor."

Um. If this gene was the result of a mutation, isn't it possible, at least in
theory, that mutation happened more than once? At two different times? At two
different branches on the species tree?

Not really my area but there seems to be an assumption that species
development (dare I say evolution) was linear, with humans being the ultimate
achievement in that process. But doesn't the fact that genes mutate -
sometimes triggered by viruses - imply the process was not at all linear?

~~~
gort
> Um. If this gene was the result of a mutation, isn't it possible, at least
> in theory, that mutation happened more than once? At two different times? At
> two different branches on the species tree?

Genes are long sequences of information. You could easily have quite different
genes doing similar things, but if you have the very same gene (sans minor
differences) it's just too unlikely to have originated completely
independently twice.

The closest thing I can imagine to your scenario is where, because of shared
ancestry, 2 species have a certain gene, and then some minor mutation hits
both of them, and now they both have some other gene. I suppose that's
possible. But they already shared the original gene to start with.

~~~
chiefalchemist
> " it's just too unlikely to have originated completely independently twice."

Unlikely, but not absolutely impossible. Correct?

Editorial: This is where Science / science loses me. It makes absolute
statements that aren't in fact truly absolute.

The point being, __if__ there was a chance identical mutation that changes (a
lot?) of things. Truth be told, life coming into being has to be a couple
orders of magnitude coincidental than some gene mutation. In that context,
"too unlikely" starts to feel much less so, yes?

~~~
lisper
> Unlikely, but not absolutely impossible. Correct?

Correct but irrelevant. Winning the Powerball 100 times in a row is also not
absolutely impossible. Nonetheless, it won't happen.

~~~
pvaldes
Yep, the aura of statistics can blind us. It will most probably happen if
enough numbers of people keep trying again and again for the next ten millions
of years. Would be not much different as and asteroid falling on earth once an
killing most animals.

~~~
lisper
An asteroid wiping us out is _vastly_ more likely than someone winning the
Powerball 100 times in a row.

~~~
pvaldes
Is just an example of how unprobable things can still happen

Think about winning the spermatozoan race 2 millions of times in a row, as
member of the most intelligent species known in the universe, one among
millions of different forms of life, after surviving five consecutive massive
extinctions that wipped the 90% of the life in the planet each time.

Statistically speaking, we can't be real.

~~~
lisper
Flip a coin 100 times. The odds of getting the _exact_ sequence of heads and
tails that you got are about 0.00000000000000000000000000001% (give or take a
zero). And yet, it happened!

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Aardwolf
"Of all the genes in the human genome, 55 percent were already present in the
first animal."

AFAIK, genes contain base pairs, and a base pair encodes 2 bits of information
(computer engineering perspective here ;))

When they say 55% is the same, do they mean: 55% of genes have a similar
structure and amount of basepairs, or do they mean: exact same values for the
base pairs bit for bit?

Like for example gene rs4778138 has an effect on eye color (handwavy first
search result of snpedia for the example here). So if in two humans, this
rs4778138 has a different value, do they consider both humans to have the same
gene (because it is one that encodes eye color to some value in each case), or
a different gene (because it encodes a different eye color)?

~~~
carbocation
Generally, let's say that a gene is a stretch of DNA that encodes some
functional product. That product might be a protein, or an RNA that performs
some function. Think of these stretches of DNA as distinct entities that can
be recognized by start and stop signals.

If you say that 55% of the genes in the human genome were already present in
the first animal, then you're saying that stretches of DNA which bear a
significant similarity to 55% of ours were found in the first animal.

~~~
Retric
It's also far less profound than you might think as cells are extremely
complex and don't have that much wiggle room. They hit a local optima after
hundred of millions of years so it's a really good one.

Not just copying DNA, but also a cell wall and nucleus etc. On top of that
multi cellular organisms are on the evolutionary slow lane, they have smaller
populations, take longer to reproduce, and don't simply hot patch any random
bit of DNA they come across.

~~~
reubenswartz
This is a great comment and I agree almost completely. However, I think it’s
very profound— it says something about the incredible power and versatility of
cellular building blocks.

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jonmc12
Here are some related papers that speak to timeframes and adaptations related
to these early animal genetics.

Metazoa (760mya) - "animal multicellularity (gene regulation, signalling, cell
adhesion, and cell cycle)"

Eumetazoa (760-680mya) - "Characteristics of eumetazoans include true tissues
organized into germ layers, the presence of neurons, and an embryo that goes
through a gastrula stage." [1]

Planulozoa (680mya) - "A 2004 study investigated the relationships between
biradial and bilateral animals in evolution. If biradial is the link between
radial and bilateral, then would seem to suggest that bilateralism occurred
before cephalization. Called the Planulozoa Hypothesis, the authors suggests
that ctenophora are the sister clade of bilateralians, and that all three of
the groups – cnidarians, ctenophora and bilaterals – are the descendents of a
single bilateral ancestor." [2,3]

Bilateria (650mya) - "A Hox system is thought to have arisen (indicated by a
red bar) after the divergence of the cnidarians from the common ancestor that
gave rise to bilaterian animals (ecdysozoans, lophotrophozoans and
deuterostomes)." [4]

[1]
[https://en.wikipedia.org/wiki/Eumetazoa](https://en.wikipedia.org/wiki/Eumetazoa)
[2]
[https://en.wikipedia.org/wiki/Planulozoa](https://en.wikipedia.org/wiki/Planulozoa)
[3]
[http://biologicalexceptions.blogspot.com/2015/02/mirroring-e...](http://biologicalexceptions.blogspot.com/2015/02/mirroring-
evolution.html) [4]
[https://www.sciencedirect.com/science/article/pii/S096098220...](https://www.sciencedirect.com/science/article/pii/S0960982206017787)
[5]
[https://pdfs.semanticscholar.org/3003/cc4844fe878fbe00167da6...](https://pdfs.semanticscholar.org/3003/cc4844fe878fbe00167da6d8206d59a67f3c.pdf)
\- list of gene adaptations by LCA.

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dclowd9901
"The new genes also proved to be remarkably durable. Of all the genes in the
human genome, 55 percent were already present in the first animal."

I read a line like that and I can't help but think of a Prometheus-style
situation with the Earth and its species.

~~~
JoeAltmaier
I'm not so sure. You build on a foundation, any foundation, you quickly can't
live without it. Not clear that a different initial foundation wouldn't also
have been frozen forever. Don't have to imagine 'intelligent design'

~~~
lainga
Your comment only unsettles me and makes me think we're carrying around the
COBOL of genes...

~~~
JoeAltmaier
Hey the Internet rests on old POP servers etc. Bad ideas from the 90's,
compounded to the Nth degree. Its turtles all the way down.

~~~
dragonwriter
> Hey the Internet rests on old POP servers etc. Bad ideas from the 90's

POP, even POP3, is from the 1980s. And I'd actually newer than a lot of the
stuff the internet rests on.

Ideas, bad or otherwise, from the 1990s, aren't comparatively new,.as much as
“the 90s” seems to often be used as a generic term for ancient history.

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dzonga
I took this MOOC course, called Model thinking. One thing that blew me away
was Cellular Automata. How complexity can arise from simple rules e.g Yes or
No. From then I knew how simply evolution or 'creation' happened.

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mmjaa
Question for the serious: is this first animal not God?

~~~
pc2g4d
Not in the traditional "uncaused cause" sense, but I guess you could spin it
that way. Probably a better analogue would be Adam and Eve.

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brugidou
À assez

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olivermarks
What's the difference between an evolutionary biologist and a philosopher?
There seems to be a lot of conjecture and theories here presented as fact...

~~~
searine
What conjecture?

This is empirical. The researchers are observing the DNA from different orders
of life (based on their extant species) and comparing them. They report their
quantitative similarity.

What about that is not factual?

~~~
d0100
The cause?

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camjohnson26
Anyone with an open mind should read Darwin's Doubt by Stephen Meyer. He looks
at possible explanations for the Cambrian Explosion and concludes that
Intelligent Design is the best explanation. Evolutionary Biologist Jerry Coyne
has written a response to it.

[https://www.amazon.com/Darwins-Doubt-Explosive-Origin-
Intell...](https://www.amazon.com/Darwins-Doubt-Explosive-Origin-
Intelligent/dp/0062071483/ref=sr_1_1?ie=UTF8&qid=1525790601&sr=8-1&keywords=darwin%27s+doubt)

[https://www.forbes.com/2009/02/12/evolution-creation-
proof-o...](https://www.forbes.com/2009/02/12/evolution-creation-proof-
opinions-darwin_0212_jerry_coyne.html#6db6c86a3500)

~~~
dwaltrip
Unfortunately, "intelligent design" is not a scientific theory. It doesn't
provide any method for categorizing life on Earth (e.g. what actually makes
two kinds distinct), and it makes no concrete, specific scientific claims
about how and why different forms of life are found in different parts of the
world (here's an easy one: why do islands and other isolated regions have such
unique life?). The list goes on.

It's also disingenuous to ask people "to have an open mind" when the
overwhelming weight of scientific evidence and consensus strongly supports
evolution. There needs to be a damn good reason to bother looking at a lonely
contrarian argument, especially as it has likely been debunked already.

~~~
whatshisface
This kind of meta-argument ("not a theory") rubs me the wrong way. It's a
concrete claim about what happened (a mind much like ours but smarter made
decisions about what stuff there should be, and then assembed it.) It can't be
dispoven because no matter what you find you could say that it was just
designed that way, but neither can evolution strictly speaking because there's
the anthropic principle to reckon with (no matter how unlikely we were to
arise, here we are. There's a nonzero chance of it all just tunneling
together, and it's a big universe - if you could somehow show that our
existence depended on a one in 10^9999999 chance, we'd just say that it
happened.)

Still, I feel that couching Christian or other religious faith in "theory"
language is not completely honest. I don't think anyone really supports
intelligent design, as opposed to Jesus speaking the world into being design.

~~~
dwaltrip
It's not really a meta-argument. It's just saying the basic requirements. If
you are challenging a strongly supported scientific theory but have no
alternative theory, then you are going to have a hard time.

Even a religious theory like intelligent design or creationism should produce
abundant physical evidence that could be assessed. And they should attempt to
integrate with all neighboring scientific fields of study (geology,
anthropology, genetics, etc). But this doesn't seem to happen.

~~~
whatshisface
Intelligent design is not specific enough. The equivalent would be saying
"random processes" instead of mutation+selection+heredity. Still, with a
specific theory of evolution that's supported we can climb back up and say
that "random processes" are probably what happened - not because it makes
predictions, but because it is a trait of a theory that does make predictions.

Likewise for ID, which is a property shared between many theories which
actually do make predictions. Successful predictions? Maybe not but they do
count as hypotheses. (building on the point that nobody in practice actually
supports ID, but instead supports a more specific genesis story that happens
to fall under ID.)

