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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.

This raises an even more interesting question. What if a civilization such as ours existed tens of millions of years ago and we are not aware of it? I am not suggesting human beings were present 10's of millions of years ago, but perhaps an earlier super species.

This is an interesting hypothesis, but it would be even more interesting if we had a method of testing it.

How to test this hypothesis:

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.

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

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.

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.

The test:

1. What to look for - Industrial tracers

A suitable industrial tracer must meet three criteria:
1. Entirely of industrial/anthropogenic/xenobiotic origin.
2. Is widespread in the atmosphere, causing it to be a detectable contaminant of most of the earths recently laid sediments.
3. Very stable in the environment over time.

For example, we might look for organic pollutants. PCB's, DDE (metabolite of DDT) and phthalates (plasticizers) are all found in remote marine atmosphere (Report in Science, p163, Vol. 211, 1981). These compounds are all exclusively industrial in origin. DDE and certain congeners of PCB are also very stable in the environment.

2. Where to look
Let us assume the PHC would cause a mass extinction, as does our existing civilization. The target sediment will surround and incorporate extinction event sediment. For example, KT Boundary clay. A good place to look might be cores from the ocean drilling program (ODP) as they are less likey contaminated (see ODP leg 171B - http://www-odp.tamu.edu/publications/prelim/171B_prel/171Bintro.html)

3. The experiment
Examine extinction event sediment for presence of an industrial tracer (IT). ie. most environmental labs can detect a wide range of anthropogenic pollutants down to parts per trillion. If IT is present in extinction event sediment, this will indicate a PHC.

4. Control
Industrial tracer levels should be checked in sediment from random sites in fossil record.

Any suggestions from the list greatly appreciated.

Mark Harvey
Southern Cross University

50% of the worlds flora and fauna could be on the path to extinction within the next 100 years - National Geographic