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RE: mass extinctions and technology

Thomas and all,

At 09:02 AM 27/09/2002 -0400, you wrote:
>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... :-)

You have got to start somewhere. To my knowledge, the organic environmental geochemistry of extinction boundary sediments has never been examined.

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!).

You are forgetting the dimension of time. We may be abundant and widespread, but for how long? One of the explanations given for SETI (search for extraterrestrial intelligence) NOT receiving any alien broadcasts is that civilizations capable of radio technology don't last long.

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

Shopping malls and airports are relics of the last 100 years. This gives them a very short window of opportunity for preservation. How much of the pyramids will remain in even another 10,000 years?

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.

This homogenization could be obscured by an associated mass extinction / climate change = sea level instability.

All these factors will make our presence exceedingly preservable.

I think limited visible (> 1mm) evidence of our civilization may survive, but a combination of factors might render the evidence hidden, unrecognizable, or simply unrecognized. ie. scarcity, burial, erosion, metamorphosis or confusion with contemporary trash.

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

It would certainly by recoverable, but you would have to be looking for the right tracers in the right environment.

> 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.

Good point, but maybe such disruption has been metamorphosed. Also, I do not know the estimated depletion of earths late Paleozoic coal deposits. If we have only scratched the surface of these deposits, then this would reduce the chance of the same deposit being mined twice.

> 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.

I totally agree with you . It takes an impact scenario these days to get the public interested in mass extinction (see the first five minutes of "Armageddon" where Bruce Willis clubs golf balls at the Greenpeace protesters from his oil platform). Try to tell someone that the earth is warming by .5 celcius every 10 years and they will yawn and turn up the sport on the television.

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

No-one was invoking an impact hypothesis until the boundary sediment's inorganic geochemistry was checked for by Walter Alvarez.

, 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.

I think an alien landing is far less likely to leave globally ubiquitous geochemical footprint. Having said that, NASA will probably get around to checking for these compounds on Mars before anyone bothers to check earth. I think the real reason we are slow to check these old sediments ( from the perspective of organic environmental geochemistry) is that:

1. The technology has only been around to do so for 20 years
2. We think we are pretty special (see the dark ages when we literally thought the univers revolved around us)