Interesting. I've heard this viewpoint before, but as Conway Morris himself admits, it's far from being a universal viewpoint in evolutionary biology. Indeed, some of Conway Morris' own work has been influential on many who hold to the contrary viewpoint. For instance, Stephen Jay Gould's Wonderful Life is mostly about Conway Morris' work on the fossils from the Burgess Shale, and the way I read that book it suggests that Gould thinks quite the opposite:
Among the speakers will be Professor Simon Conway Morris, a Cambridge University evolutionary biologist, who says there is good reason to think aliens exist — and that they may well have chemical and biological similarities to us.
Conway Morris, whose talk is entitled “Predicting what extraterrestrial life will be like — and preparing for the worst”, said: “My basic argument is that, contrary to most neo-Darwinian thinking at the moment, evolution is much more predictable than people think.
“In particular, I would argue that the emergence, by evolution, of intelligence, cognitive capacity and all that stuff is an inevitability.”
In short, under the right conditions of a “biosphere” such as that present on Earth, the molecules necessary to form complex and intelligent life are already available; Darwinian evolution will do the rest.
“I think we can argue some intelligence must emerge in a biosphere,” said Conway Morris. “If that is correct — and it applies to manipulative skill — then that suggests there should be alien technologies.” (pp. 319-320)
... if, had Homo sapiens failed and succumbed to early extinction as most species do, another population with higher intelligence in the same form was bound to originate. Wouldn't the Neanderthals have taken up the torch if we had failed, or wouldn't some other embodiment of mentality at our level have originated without much delay? I don't see why. Our closest ancestors and cousins... possessed mental abilities of a high order, as indicated by their range of tools and artifacts. But only Homo sapiens shows direct evidence for the kind of abstract reasoning, including numerical and aesthetic modes, that we identify as distinctly human. All indications of ice-age reckoning -- the calendar sticks and counting blades -- belong to Homo sapiens. And all the ice-age art -- the cave paintings, the Venus figures, the horsehead carvings, the reindeer bas-reliefs -- was done by our species. By evidence now available, Neanderthal knew nothing of representational art.I'm not sure I'd go quite so far as Gould, but I do think that if Pikaia, for instance, had not survived the catastrophe at the end of the Permian, it's far from clear that an advanced civilization would have arisen. There are a gazillion ways for living things to adapt to their environment that have nothing to do with intelligence. Consider something like Paramecium; its cell structure is immeasurably more sophisticated than ours. Incredible adaptation... but no good for building rocket ships or writing The Critique of Pure Reason (or even Valley of the Dolls). On the other hand, if sufficiently sophisticated brains do appear, I think there's a good chance that sooner or later memetics will take hold in a big way and hasten the development of abstract reason. However, there's no telling how long that would take.
Conway Morris goes further and suggests that we shouldn't count on any hypothetical alien civilization to be friendly, nor should we expect them to think any better of us. He's hardly alone in this; anyone who's read Pellegrino and Zebrowski's The Killing Star will recall the Three Laws of Alien Behaviour:
1. Their survival will be more important than our survival. If an alien species has to choose between them and us, they won't choose us. It is difficult to imagine a contrary case; species don't survive by being self-sacrificing.With this in mind, it is particularly chilling to note that any civilization capable of fast interstellar flight is capable of wiping out other civilizations; any relativistic spacecraft is potentially a relativistic kill vehicle (indeed, this is the whole point of The Killing Star). Given this, it seems quite reasonable to suppose that any alien civilization that detects our radio signals (or other evidence of our existence) will not necessarily want to advertise their own presence. For his part, Conway Morris suggests that we take similar cautions in the event that we do detect evidence of intelligent life.
2. Wimps don't become top dogs. No species makes it to the top by being passive. The species in charge of any given planet will be highly intelligent, alert, aggressive, and ruthless when necessary.
3. They will assume that the first two laws apply to us.