Xenoarchaeology - Resource



It has recently become fashionable to postulate that ETs landed on our planet ages ago, whether to influence our biological or social evolution, to collect zoo specimens, or to make anthropological surveys. Extravagant speculations abound: One bock attributes to alien benevolence the discoveries of subatomic physics, general relativity, and the double helix!

Xenoarchaeology -- the search for evidence of ancient visitation by interstellar travelers -- is at best a difficult and confused field of study. Precisely because hopes and expectations are so high, it is often harder to maintain a strong, healthy skepticism. Hence, in the words of astronomer Carl Sagan, "we must accept arguments for extraterrestrial visitations to earth only when the evidence is compelling."

At present, an exhaustive survey of all pertinent literature and other evidence fails to uncover a single incontrovertible case of past alien presence on our planet.

Of course there is nothing a priori absurd about the basic idea of ancient astronauts. The Hypothesis of Mediocrity allows that, as a general rule, when one goes exploring one finds inferior things. For example, Columbus discovered America because European transportation technology was well advanced beyond that of the native Americans. Were this not the case, the natives would have discovered Europe! It is plausible to conclude that if the Galaxy is teeming with life, a superior intelligence from another star system could have visited Earth for any of a myriad of good reasons.

Speculation has centered on three specific areas. First, there is the possibility that aliens arrived geological timescales (millions or billions of years) ago. Biochemical and genetic evidence has been marshaled in an attempt to demonstrate that our natural biological evolution may have been adjusted, enhanced or tampered with in some manner.

A second proposition is that extraterrestrial "gods" and "saviors" have materially affected the development of human society and culture. The most common evidence advanced in favor of this is the virtual ubiquity of legends describing visitors from the sky. Usually these yarns seem to suggest either that the human race was exported to Earth from other worlds, or that ETs came among men and helped launch human civilization.

Naturally, a mere account of strange beings who live in the heavens and perform miracles is not compelling proof. (Where else might gods reside but in the skies?) And the clear correlation between the movement of stars and constellations in the celestial vault and the changing seasons has probably been recognized at least since the emergence of Cro-Magnon man. Primitive belief systems often attribute divinity and magical forces to such regular features in the environment.

Yet how easy it would be for an alien humanoid to "curse" hapless natives with a portable x-ray machine! It may be that all interstellar First Contact operations include a Thaumaturgy Division, whose duty it is to create miracles and god-myths to keep the curious at a safe distance in the unlikely event of an emergency landing. These thaumaturgists could create spectacular displays to awe primitive onlookers, such as transmutation of drinking fluids, variable-rigidity lances, and advanced force-field technology (which might perhaps be demonstrated on local bodies of water).

The third specific area of xenoarchaeological research is the quest for alien artifacts and other physical manifestations of their presence. This is of great importance, because it is often urged that in such important matters "the only acceptable evidence would be hardware." For instance, the discovery of a piece of advanced electronics embedded in a coal seam millions of years old, accompanied by indisputably nonhuman skeletons, might be acceptable as convincing evidence of past visitation. Another common suggestion is that the aliens might have left a durable marker of some kind, such as the black monolith depicted in the science fiction movie 2001: A Space Odessey. In fact the Moon would be an ideal location: The artifact would last millions of years without disturbance and could only be detected by a reasonably advanced spacefaring civilization.

But we must beware of technological chauvinism in assessing possible artifacts. We can interpret certain objects as airfields, nails, or evidence of the use of nuclear explosives, but this is because we have just acquired this technology ourselves. Two hundred years ago the interpretation would have been much different; two centuries hence, it will again radically change. The fact is that the technology of space visitors will most likely be highly non-contemporary with our own.

The problems involved in tracking down evidence of extraterrestrial contacts in ancient times are vastly different from those of conventional archaeology and anthropology. It would not be remarkable if a few brief visits by ETs to limited areas of this planet have left no traces. Continental drift and tectonic shuffling, ice ages, volcanic activity and sedimentation will have taken their toll.

Archaeologists generally search for human settlements. Yet the chances of, say, a spacecraft crash landing near one of these is extremely small. It is highly unlikely that we could ever detect anything less than widespread, intensive alien involvement.

Let us assume arguendo that ten aerial vehicles crashed somewhere on Earth in ancient times, spewing their debris over a swath covering 10,000 m2. If the affected stratum is one meter deep and lies under an average of 10 meters of sediment, this leaves about 1015 cubic meters of soil and rock to be examined.

If we then assume that all crashes occurred only over that 10% of the Earth’s land area which is "interesting" to the ETs, and that there are ten archaeologists with suitable engineering and technical credentials searching full time for the sites (excavating an average of 10 m3 each day per investigator), it would take roughly 15,000 years just to have a 50/50 chance of finding a crash site. Even then, and assuming favorable corrosion conditions, the chances of spotting recognizable remnants of an accident would still be miniscule.

For these reasons and others, many have renewed the hunt for reconstructable contact legends passed down from early human civilizations. There is some reason to cautiously assert the validity of this technique, because we know that historical events have occasionally been faithfully recorded in myth and folklore.

Perhaps the best-known of these was the first meeting between the Tlingit people on the northeast coast of North America and a European expedition in 1786 led by the French explorer Jean La Pérouse. The oral native account of the incident remained true to the original a century later, although some of the descriptions of advanced European technology (e.g., giant sailing ships) had acquired a distinct mythological flavor over the years. And many other accounts of such phenomena as supernovae and great floods have likewise survived through centuries of verbal narration.

One useful test of the validity of legendary encounters with ETs might be whether or not information is contained in the tale which couldn’t possibly have been generated by the primitive civilization itself. For example, an ancient manuscript containing modern circuit diagrams or a "holy number" worshipped throughout the ages (which turned out to be the transcendental e or the nuclear fine structure constant) might be sufficient if it could be independently authenticated.

Carl Sagan has articulated three factors which maximize the probability that an historical encounter with aliens would be recorded in a reconstructable manner:

1. The account must be committed to writing soon after the event; 2. The contacted society undergoes a major change because of the contact; and 3. The aliens make no attempt to disguise their exogenous nature.

If these stringent requirements can be satisfied in even a single instance, xenoarchaeologists may be able to secure proof that Earth has been visited by intelligent ETs.