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Unread August 17th, 2006, 11:51 PM
Carey N Carey N is offline
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Join Date: Jul 2004
Location: New Jersey
Posts: 138
Default Re: Battle Against Scientific Illiteracy

Quote:
Life on Earth seems to have begun around 4 billion years ago, but for most of that time not much seemed to be “evolving” except for single cell stuff and some algae . . . until the “Cambrian Explosion,” a little over ½ billion years ago, when lineages of almost all animals we see today, rather suddenly, appeared
There are several problems with this:

1) To characterize pre-Cambrian life as "not much" is very strange . . . the origin of bacteria in the first place was momentous (this is where you should really have directed your critique; too late now, though), and how about the evolution of photosynthesis, eukaryota, and multicellularity? Invertebrates and early chordates also arrived tens of millions of years before the Cambrian.

2) There is no doubt that a lot happened in a relatively short time period in the Cambrian, but 'relatively short' is an important phrase. We're talking about ~40 million years, here. Also, our knowledge of the Cambrian is largely restricted to the Burgess Shale fossils, which represent only a thin 'slice' of time and give the false impression that the origin of new phyla was "all-of-the-sudden".


Quote:
. . . and today, somehow, voila, we sapient beings find that we exist
Here is a diagram depicting your conception of life on Earth:

[Nothing Much] - - -> [Cambrian Explosion] - - - [Voila!!] - - -> [Humans]

I don't even know where to start with this one. Just consult a biology textbook and another resource on hominid evolution.


In previous posts, you have implied that biologists have it all wrong, that they are delusional about what 'the evidence actually tells us regarding the origin and evolution of life', that they are a bunch of self-important, myopic people. I ask for some enlightenment, and you respond by describing the work of paleontologists and evolutionary biologists. But wait . . . didn't you say that they don't know what they're talking about?




Quote:
some Darwinians say the explosion and sapient beings are the result mostly of chance, while some contend that the explosion and sapient beings are here b/c our planet would have created selection pressures to make it so
No one with all his marbles thinks that higher intelligence (or any other adaptation) is the result of pure (or mostly) chance . . . rather, Gould posits that, if we were to re-run the history of life, things might turn out very differently (e.g. if the earth's orbit were such that the end-Cretaceous asteroid didn't hit us, mammals would probably not have radiated, and we wouldn't be around). In that sense, some chance events were important for the evolution of many species, including our own. Conway-Morris, on the other hand, thinks that we'd still see the evolution of higher intelligence, even if those chance events happened differently - if sapience didn't evolve in mammals, then it would have arisen in some other lineage (e.g. reptiles). His argument is based on the notion of convergent evolution, but is riddled with problems and broadly rejected. I attended a talk of his on this subject - you would have agreed with me that his hypothesis is not compelling.

Last edited by Carey N; August 19th, 2006 at 01:51 AM.
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