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RE: mass extinctions and technology

>Hi all,
> An old question I would like to reintroduce:
>   "If human beings were to become extinct in the next 500 years due to
> global warming, pestilence or other catastrophe, what if anything would
> remain of our civilization to reveal us to the next super species, 65
> million years from now?" .
> I sent a standard email to 100's of paleontologists and archaeologists
> (PHd's in the USA and worldwide), asking this question to try and
> get some
> consensus. I received approximately 60 replies. The results are as
> follows.  About 20 thought there would be direct evidence to reveal
> us.  About 30 were uncertain.  About 10 thought there would be no
> evidence
> to reveal us.
> There seems to be no consensus in paleontology and archaeology.

Perhaps no concensus, but science doesn't work by polling... :-)

I find it spurious to think that the presence of a technologically advanced
(and, consequently, numerically abundant) organism would have little
preserved fossil record.  Using our only known sample (us), let's take a
look at a few aspects of our preservability:
* We are abundant, and indeed within the last century are probably the most
common large-bodied vertebrate species on the planet (with the possible
exception of those species that we have made: i.e., the domestic critters)
* We are geographically widespread and inhabit a wide variety of
* We have a distinctive morphology which is as easily preservable as any
other vertebrate

In other words, we have all the attributes of an index fossil (save only the
one we can't test yet: our duration on the planet!).

Additionally, our remains and the remains of our technologies (i.e., trash)
make their way into many of the depositional environments  (i.e., future
sedimentary rocks) of the world.  The sediments of the Mississippi, Nile,
Ganges-Brahmaputra, etc. river valleys and deltas, and even the deep sea
floor, are littered with bits of our machines, our manufactured waste
products, and occasional representatives of us.

We have engaged in largescale transformation of the surface of the earth:
the foundations of shopping malls, airports, strip mines, etc. are some
rather large and distinctive trace fossils!!  (Particularly the latter, as
they actually enter the rock rather than merely unconsolidated sediment or

We have been responsible for mass extinctions, but also for the large scale
homogenization of the terrestrial (and to a lesser degree aquatic) biota of
the Earth; useful and pest species are conciously (or unconciously)
transported by us across the planet.

All these factors will make our presence exceedingly preservable.  The only
way that I envision our presence not being recoverable in the 10s-100s of
millions of years time scale would be if, for some reason, all Holocene
sediments and surfaces were somehow removed from sampling.  This seems very

> Make the following assumptions:
> 1.   Locatable and identifiable remains of a Pre-Human Civilization (PHC)
> are mostly microscopic
> Widespread microscopic remains of PHC's may exist in the sedimentary
> record. The remains may be in the form of  particles, persistent organic
> pollutants, trace elements, isotopes or other types.

See above why this assumption is not necessary valid.  However, I agree that
our chemical presence is equally well-marked for the future.

> 2. Given two isolated civilizations, be they isolated by time OR space,
> technology will evolve along similar lines.

Actually, a VERY questionable assumption, given our very small sample size.
However, since our sample is all we have to go with, it is the best we can
do.  Additionally, check out Jared Diamond's Guns, Germs and Steel for some
interesting observations about the history of our species and its
technology.  For example, there are good arguments to be made that the idea
of writing may have only been developed twice independantly (Sumeria &
Mesoamerica), and that all other writing systems were developed with the
knowledge and experience that some other people were able to make marks to
record information.

> Common themes will prevail, with regard to the technological
> progression in
> isolated civilizations. This is given that many natural laws, that
> constrain or direct technological advancement, would be
> consistent between
> the two systems. This assumption is more relevant to civilizations
> separated by time, as the physical environment is more likely similar.
> For example, if we consider two such earth civilizations, we might expect
> to see non-sustainable utilization of the earths resources in both. Such
> activity might include fossil fuel energy or mass extinction. We
> might also
> expect to see the development of synthetic compounds such as persistent
> organic pollutants.

Based on this, we have substantial evidence that no PHC ever developed
coal-based technologies, as there is no sign of non-human disruption of the
late Paleozoic coal deposits of the world.

> It seems intuitive, that the more fundamental the technology, the more
> likely it will be common to both civilizations. Whereas the more
> elaborate,
> or obscure a technological advance, the less likely we would see it
> represented in both civilizations.
> 3. Let us assume that mass extinction and heavily industrialized
> civilization are closely related.
> Let us assume the PHC would cause a gradual mass extinction, as does our
> existing civilization.

WHOA there!!  Check your time scales!  What appears to be a "gradual mass
extinction" at the scales of human societies would look like an
instantaneous event from the point of view of a couple of million years from
now or more.  In fact, it would BE what a geologist would refer to as an
instantaneous event.

While your hypothesis is interesting, and the tests you suggest would
certainly be useful in supporing the claim of a PHC, let's not lose sight of
Occam and multiply entities unnecessarily.  As there are as yet no good
indication of the presence of said PHCs (either their bodies or their
technologies) in the fossil record, and as other physical factors
(terrestrial and extraterrestrial) can reasonably be invoked for the cause
of mass extinctions, then looking for PHCs at present is comprable to
looking for evidence of paleo-time scale alien landings.  Sure, it would be
phenomenally interesting!!  But I would want a lot of good additional
supporting evidence before I went invoking this as a possible cause.

Would make an excellent plot to a great science fiction story, though.

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796