I'd like to say here that I'm extremely skeptical of the dolphin communication experiment listed earlier. If it shows up in Nature or the like, call me. Until then, I'm going to continue to think that dolphins are very smart, but not on a human level.
Sorry, but I don't understand how people can think being skeptical means hearing something and thinking to themselves "That idea doesn't fit my worldview, so I'll just assume it's wrong... not that I'm actually going to do any research or reasoning to back that up." People who, instead of looking at what information and evidence is out there and concluding what to believe based on that, would rather decide what's true based on weather it supports their existing beliefs. Such behavior is arrogant and dogmatic- a kind of willful ignorance that I absolutely cannot stand. It's antithetical to truth, to science, and to the essence of being a creature capable of reason.
Also, of course dolphins aren't smart on a human level... that's comparing apples to oranges. Can you say if Elephants are smart on a Pidgeon level? With their different physical adaptations and brains, there's no way to make a fair comparison; would you say Elephants are idiots compared to Pigeons, because can't even sense a magnetic field to navigate? Of course not.
Dolphins aren't on a Human level, they're on a Dolphin one. We don't know enough even about our own brain to know the capabilities of theirs, but we do know they have the ability to emit and see ultrasonic "images", and reproduce these images vocally to one another in a way wholly unlike the language and sensory capabilities of Humans. Whether these vocalizations have some form of syntax or can convey more abstract concepts has yet to be determined, but these capabilities and the ability to share and reproduce them with each other exists, as does the ability of humans to read and convey these sounds back to them, whether it's a comfortable idea for you or not.
Well, we know that Neanderthals had Religion, or at least we're fairly sure they did, and we're fairly sure that Dolphins don't, so we know that Dolphins must be either less intelligent or less curious than Neanderthals. Or they somehow know SCIENCE without any kind of lead-up.
Yeah, when we view evolution and the natural world, there's this old idea that there's a long chain of more and less evolved organisms, with amoebas and bacteria at the low end, and humans at the top... and this idea is all kinds of wrong. Now, humans are absolutely bitching, and we can do many things no other animal can do. However, we're just adapted for our environment and the pressures the world has put on us, as other animals are adapted for theirs. Every living thing is equally, but differently, evolved.
Also, we are far from sure that Neanderthals had anything like a religion. They did bury their dead, though. Some people claim that a pile of bear bones in a cave is evidence of "bear-worship", but aside from proximity to a Neanderthal dwelling, there's no reason to think they were responsible for it. I don't mean to say that the capacity for ritual behaviors is limited to humans, though... We've known since the 1950's that Elephants practice burial rituals, and close family members have even been known to go out of their way to visit the burial sites for years afterward. Also, during wildfires in West Africa, the leaders of grassland Chimpanzee troupes have been observed performing ritual dominance displays, which they direct at the wildfires before an audience, and have been known to harness and control fires as well. There's no biological purpose to the ritual, and it exposes them to significant risk, but it matches the displays they use to express their superiority to other Chimps, which makes the whole thing very interesting indeed.
Humans are awesome, but the capacity for learning, for abstract rituals, and even for verbal communication are not uniquely ours, and for us to continue to assume so is asinine. When considering this in light of Human intelligence, consider that if you dropped off a new generation of, say, American citizens into the deep jungle without teaching them anything of language, science, or the world, assuming they survived to adulthood they'd be little different than land-bound social apes. Technology and language aren't in our DNA, and what we like to think of as Human brilliance is really just the accumulated experiences passed down to us from our forebears, thanks to the invention of language.