What caused the Cambrian explosion? | Hacker News Reader

What caused the Cambrian explosion?

whyevolutionistrue.wordpress.com

23 pointstokenadult9 comments

It's important to note that in geologic terms, the Cambrian Explosion really refers to the proliferation of hard-bodied organisms. There's almost definitely a sudden increase in global biodiversity, but it's an increase in fossil preservation that gives it the name "Cambrian Explosion".

Fairly complex lifeforms were around well before the Cambrian (e.g. the Ediacaran Fauna [1]), and even some hard-bodied organisms were around before (the "small shelly fauna" [2]).

At the start of the Cambrian, though, hard body parts (i.e. biomineralization) really took off. It's often hypothesized to be an "evolutionary arms race" with armor and teeth.

In that context, weathering of the continents influencing the chemical composition of the seas and therefore making it easier for organisms to grow hard body parts starts to make a lot more sense.

[1] http://en.wikipedia.org/wiki/Ediacara_biota [2] https://en.wikipedia.org/wiki/Small_shelly_fauna

Also, I just noticed that the article links to something in New Scientist. The paper it refers to was published earlier in Nature: http://www.nature.com/nature/journal/v484/n7394/abs/nature10... Google Scholar tells me there's a pdf here, if anyone is interested: http://211.144.68.84:9998/91keshi/Public/File/34/484-7394/pd...

The cambrian explosion is really interesting but I'd rather read about the thing itself, not framed as a polemic against creationism. I don't care about creationism.

Science education is so damaged in the United States now that a survey of people on the street would probably find a worryingly high percentage of people believed either a) the "Cambrian explosion" was an asteroid impact, b) involved explosives, or c) took place over a matter of hours or days.

It's not only science education; what I see here in the US (and I am saying that as a practicing Catholic from Europe) is a problem with people's faith. They think it's under assault and in need of defense, they think God's word isn't strong enough to hold its own in the world, and that's where these weird arguments in favour of creationism comes from. I think they have crossed the line into blasphemy.

You even have this phenomenon of Cleanflix, this Mormon endeavour of beeping out rude words in Hollywood movies, because they are seen a threat to their worldview. This is for the same reason; they have weak faith.

Exactly. If someone's "faith" needs proof, then it's hardly faith anymore, is it?

You can't really frame conflicts with these people in terms of "science vs. religion". It's more like blocking trolls who have failed at both, stopping them from taking violent swings at civilization.

I'm not a Catholic, or a classic religious person at all, but when I hear Catholics speak like this, I often go "this is not my world view, but it does make sense, relative to its premises".

I don't get the same sense at all when listening to folks from many American churches. Their stuff seems... cartoonish.

Much of the blog (and the accompanying book) appear to be constructed as a counter to intelligent design and religiously-influenced arguments. Which is all well and good, although not knowing this while reading it, I found the periodic call-outs surprising.

More about the Cambrian period, from the University of California Museum of Paleontology:

http://www.ucmp.berkeley.edu/cambrian/cambrian.php

A book review, titled "Decoding the Cambrian Radiation," of the book On the Origin of Phyla (2004):

http://www.americanscientist.org/bookshelf/pub/decoding-the-...

Lecture notes, "The Origin of Phyla and the Cambrian Explosion of Life," with color slides for an undergraduate course about fossils and evolution:

http://www.geo.wvu.edu/~kammer/g230/originphylacambrianexplo...

This idea is not original to me. But I still remember a comparison of the Cambrian explosion to a gardener looking at a major tree on his grounds and remarking "you know, it's funny that no major boughs have appeared on this tree for some time. These days, all the growth seems to be at the twig level."

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