photoFor just about as long as anyone can remember, we've been gazing into the sky, wondering if there is life on other planets and, if so, when we might hear from our intergalatic brothers and sisters. In particular, we've wondered if extraterrestrials will be like us.

We'd better hope not, researchers warn in a new study.

Evolution on alien worlds most likely will have followed the Darwinian model, meaning that the species that rise to the top will be the ones that are best at violence, exploitation and generally thuggish behavior.

They'll be like us, in other words.

The cautionary note is sounded as part of an extraterrestrial-themed edition of the Philosophical Transactions of the Royal Society A published today. The scientists urge that a branch of the United Nations must be given responsibility for "supra-Earth affairs" and formulate a plan for how to deal with extraterrestrials.

The UN branch would be expected to establish structures similar to those proposed for dealing with threats from near-Earth objects, such as asteroids, that might be on a collision course with our planet.

In other words, said Simon Conway Morris, a professor of evolutionary palaeobiology at Cambridge University, those planning for alien contact should prepare for the worst.

“If intelligent aliens exist, they will look just like us, and given our far from glorious history, this should give us pause for thought," wrote Morris.

Effect on religion

Others writing in the special edition of the journal said the sudden appearance of extraterrestrial life would have major implications for the world's religions. Might they collapse?

“Are religious believers Earth-centric, so that contact with ET would de-centre and marginalise our sense of self-importance?” asked Ted Peters, a professor of systematic theology at the Pacific Lutheran Theological Seminary in California.

After working the problem for awhile, though, Peters concludes that theologians would probably not be out of a job, and in fact might be busier than ever.

"Traditional theologians must then become astrotheologians ... What I forecast is this: contact with extraterrestrial intelligence will expand the existing religious vision that all of creation … is the gift of a loving and gracious God," he speculated.