Re: From Science News

[Sean Carroll <sean@kua.net>]

Garrison Hilliard wrote:

> NEW THEORY ON DINOSAURS: MULTIPLE METEORITES DID THEM IN
> from The New York Times

'New theory'? Actually, it's a hypothesis, not a theory, and one that 
has been around for many decades. Once again, the commercial media 
betrays its complete and total inability to comprehend even the basic 
aspects of the science most people rely on them to explain.

> For more than a decade, most scientists have believed that the extinction
> of the dinosaurs was caused by a single event: the crash of an immense
> body from outer space, 

True, I suppose. What they fail to mention is that 'most scientists' -- 
including, I might emphasise, the Alvarezes -- are in completely 
unrelated fields of specialisation and know as little (or less) about 
dinosaurs as (than) the general, non-scientifically-educated public. 
What about a statistic that takes into account the fact that there are 
many different fields within the incredibly broad rubric of 'science', 
that no one has enough time to specialise in *everything*, and that most 
scientists take the word of others to dictate their beliefs about fields 
outside their specialties? What should be relevant is what *dinosaur* 
scientists believe, not what some mythically monolithic 'most 
scientists' believe. And among dinosaur scientists, the issue is a lot 
more controversial, which is a strong circumstantial implication that 
the evidence for a direct connection is not as firm as it is portrayed 
by media outlets run by people who understand nothing of science but 
everything of how to excite people into giving up money to them through 
inflated and sceptically unexamined rhetoric.

> Now, however, scientists working in Ukraine have discovered that a well-
> known but smaller crater, some 15 miles wide, had been inaccurately dated
> and is actually 65 million years old,

I'm not susprised. In fact, I thought there were always a number of 
craters of about K-T-border age, and that the only reason Chicxulub has 
been singled out is because it's the biggest one -- the only one large 
enough to even *potentially* or *possibly* or *hypothetically* cause a 
mass extinction.

> making the blast that created it a likely contributor to the end of the 
> dinosaurs.

How could this *possibly* follow? It's based only on assumption: A 
bolide hit 65 million years ago, therefore it probably killed the 
dinosaurs. I don't accept the evidence for that even with Chicxulub, but 
at least I recognise that's based on other evidence besides mere 
coincidence in time,including shocked quartz, tektites, iridium, and 
mathematical models of the possible results of an impact of the same 
size. Unless the New York Times is being even more pathetically 
incompetent than I have already indicated, and is inexcusably leaving 
out highly relevant and important parts of the story, there is not yet 
any of this other corroborating evidence for this other impact being 
related to the extinctions -- it's based merely on a single calculation 
saying it happened at the right time.

Since when does coincidence in time count as scientific evidence of not 
only a correlation but a (partial) *causation*? There have been a LOT of 
bolides that have hit Earth all through its history -- many MANY more 
than can be made to coincide in a one-to-one or even multiple-to-one 
correspondence with mass extinctions -- not to mention that there are 
many more extinctions that are not considered 'mass' at all but differ 
from the traditional 5 or 6 mass extinctions only in being slightly 
smaller in magnitude and slightly higher in frequency -- exactly as one 
would expect from some sort of random statistical distribution resulting 
from factors purely *internal* to a nonlinear process like evolution.

(I am just waiting for someone to try to prop up the bolide-extinction 
connection by putting these two objections [that there are many other 
extinctions that cannot be qualitatively separated from the few mass 
ones, and that there have been constant bolide impacts of various sizes 
throughout Earth history] together and suggesting that ALL extinctions 
of 2 or more species within a single 5-million-year period are caused by 
bolide impacts, smaller impacts for smaller extinctions and larger ones 
for larger extinctions -- the ultimate reductio ad absurdum of the 
extreme partisan bolide-hypothesis position, which would ultimately 
amount to a rejection of all understanding of evolution and natural 
selection as biological processes, pinning all deviations from the 
old-fashioned straight-line 'Scala Naturae' progression leading towards 
humans on outside factors and not on the inherent unpredictability and 
complexity of biological evolution. In other words, just as with 
doctrinaire religion, all understanding based on factors we know and 
have experimental data for is rejected in favour of an unquestioning 
'faith' in an external power that cannot be explained except in broad 
generalities and claims to ignorance. The fact is, we know that there is 
a broad nonlinear statistical pattern of extinctions throughout history, 
and another statistical pattern of bolide impacts, and no one has yet 
been able to match the two up to anywhere near the degree needed to 
imply even correlation, let alone causation, unless someone published a 
VERY significant finding somewhere that was totally ignored by both the 
commercial media and the scientific community.)

It might do the sense of humility of the New York Times people some good 
for someone to write in and point out to them that there have been 
hypotheses about multiple K-T impacts since before the Alvarez findings, 
and such hypotheses have not caught on for a good reason: those species 
strong enough to resist one impact would be very likely to be able to 
survive additional impacts equally well, and those vulnerable to later 
impacts would have already been killed by the first one. There would be 
a few exceptions, of course, examples of the 'final straw - camel's 
back' phenomenon, but as far as I can tell no one has provided any 
evidence that a series of successive impacts would be discernably 
different in its results than a single massive impact.

Of course, these Ukraine scientists may be proposing that two impacts 
happened at ONCE and caused the extinctions. But that makes about as 
little sense -- if the Chicxulub impact was powerful enough to cause a 
mass extinction itself, what would it mea to say that this other smaller 
impact was also a 'cause' or 'contributor', without evidence that the 
effects of Chicxulub + this one would be different from the effects of 
just Chicxulub?

--
--Sean
http://www.livejournal.com/users/spclsd223/