---
title: "Potential cultural impact of extraterrestrial contact"
chunk: 5/12
source: "https://en.wikipedia.org/wiki/Potential_cultural_impact_of_extraterrestrial_contact"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T04:33:45.687876+00:00"
instance: "kb-cron"
---

=== Hostile civilizations ===
Science fiction often depicts humans successfully repelling alien invasions, but scientists more often take the view that an extraterrestrial civilization with sufficient power to reach the Earth would be able to destroy human civilization or humanity with minimal effort. Operations that are enormous on a human scale, such as destroying all major population centers on a planet, bombarding a planet with deadly neutron radiation, or even traveling to another planetary system in order to lay waste to it, may be important tools for a hostile civilization.
Deardorff speculates that a small proportion of the intelligent life forms in the galaxy may be aggressive, but the actual aggressiveness or benevolence of the civilizations would cover a wide spectrum, with some civilizations "policing" others. As among humans, civilizations may not be homogeneous and contain different factions or subgroups. According to Harrison and Dick, hostile extraterrestrial life may indeed be rare in the Universe, just as belligerent and autocratic nations on Earth have been the ones that lasted for the shortest periods of time, and humanity is seeing a shift away from these characteristics in its own sociopolitical systems. In addition, the causes of war may be diminished greatly for a civilization with access to the galaxy, as there are prodigious quantities of natural resources in space accessible without resort to violence.
SETI researcher Carl Sagan believed that a civilization with the technological prowess needed to reach the stars and come to Earth must have transcended war to be able to avoid self-destruction. Representatives of such a civilization would treat humanity with dignity and respect, and humanity, with its relatively backward technology, would have no choice but to reciprocate. Seth Shostak, an astronomer at the SETI Institute, disagrees, stating that the finite quantity of resources in the galaxy would cultivate aggression in any intelligent species, and that an explorer civilization that would want to contact humanity would be aggressive. Similarly, Ragbir Bhathal claimed that since the laws of evolution would be the same on another habitable planet as they are on Earth, an extremely advanced extraterrestrial civilization may have the motivation to colonize humanity in a similar manner to the European colonization of much of the rest of the world.
Disputing these analyses, David Brin states that while an extraterrestrial civilization may have an imperative to act for no benefit to itself, it would be naïve to suggest that such a trait would be prevalent throughout the galaxy. Brin points to the fact that in many moral systems on Earth, such as the Aztec or Carthaginian one, non-military killing has been accepted and even "exalted" by society, and further mentions that such acts are not confined to humans but can be found throughout the animal kingdom.
Baum et al. speculate that highly advanced civilizations are unlikely to come to Earth to enslave humans, as the achievement of their level of advancement would have required them to solve the problems of labor and resources by other means, such as creating a sustainable environment and using mechanized labor. Moreover, humans may be an unsuitable food source for extraterrestrials because of marked differences in biochemistry. For example, the chirality of molecules used by terrestrial biota may differ from those used by extraterrestrial beings. Douglas Vakoch argues that transmitting intentional signals does not increase the risk of an alien invasion, contrary to concerns raised by British cosmologist Stephen Hawking, because "any civilization that has the ability to travel between the stars can already pick up our accidental radio and TV leakage" at a distance of several hundred light-years. The easiest or most likely artificial signals from Earth to be detectable are brief pulses transmitted by anti-ballistic missile (ABM) early-warning and space-surveillance radars during the Cold War and later astronomical and military radars. Unlike the earliest and conventional radio- and television-broadcasting which has been claimed to be undetectable at short distances, such signals could be detected also from relatively distant receiver stations in certain regions.
Politicians have also commented on the likely human reaction to contact with hostile species. In a 1987 speech at the 42d Session of the United Nations General Assembly, Ronald Reagan said, "I occasionally think how quickly our differences worldwide would vanish if we were facing an alien threat from outside this world."