Richard Dawkins:

What if there are life forms on other planets that have evolved so far beyond our level of intelligence and creativity that we should regard them as gods, were we ever so fortunate (or unfortunate?) as to meet them?

Seems to me that Darwin is reinforcing the popular assumption that evolution is a force that continually improves the intellectual abilities of life forms, making them smarter and more capable. Dawkins is one of the most important figures in evolutionary biology so this is kind of surprising. This is certainly not my understanding of how evolution works. There is no reason to think that intelligence is a particularly adaptive trait over the long term. It’s contributed to our success as a species but it could also contribute to our extinction. And anyway, which species is the most successful at this point in geological history? How do you even measure such a thing? I’d argue that you really can’t. You can’t use long term survival as a guide because that is subject to a lot of luck and chance (a large asteroid hitting the earth being a good example of really bad luck the dinosaurs had to endure). It would also suggest that ancient animals, ones that haven’t changed much for millions of years, are the most successful and that horseshoe crabs actually rule the earth:

The oldest living animal species on Earth cannot be known for sure, because not every animal species or fossil has yet been discovered, but our current best guess is the horseshoe crab, which has remained pretty much unchanged since the Ordovician period, 445 million years ago. To put this in perspective, multicellular animals only appear in the fossil record about 600 million years ago, and the typical duration of an animal species is just a few million years. For instance, Tyrannosaurus rex lived for only about three million years. In contrast, the horseshoe crab has existed for about 74% of the time that animals in general have.

Homo sapiens have been around for perhaps 195,000 years. A blip in time. We’ve got millions of years before we catch up to even the short-lived T. Rex. It’s too early to make any assumptions about our ultimate fitness.

Humans are not evolving now other than in the microevolutionary sense. Perhaps our environment will change and speciation will occur. A “god-like” species could arise as Dawkins speculates may have happened on other planets in other solar systems. But there is no reason to expect this to be a natural outcome. New species of human could just as easily have other adaptive traits such as the ability to withstand much higher or much lower temperatures or a different mixture of gases in the atmosphere or what-have-you rather than an increase in our intellectual capacities.

So again, evolution is not always progressive. It doesn’t make organisms better in any meaningful sense. It can cause a species to lose abilities, like blind cavefish. Any trait, including blindness, that makes an individual more likely to survive is adaptive.

Here’s a good overview of evolution from Talk Origins.