When watching Thor, it is evident that Asgardians aren't the same as humans, yet they must share some characteristics - the taser knocks Thor out, and when in the hospital, he is injected with something that also knocks him out. While both events are played for comic effect, in some ways, it makes me wonder. Obviously there must be some similarities, because human things seem to affect Thor.
Are the Asgardians essentially superhumans? Or is there some other explanation?
Humans and Asgardians are nearly identical. Aside from an enhanced lifespan, increased intelligence, physical prowess (including weight) and exceptional healing, a below-average Asgardian could easily be mistaken for an above-average human.
As to whether they're Superhuman, the answer is a qualified maybe. There's an extremely strong impression given that there is extensive common ancestry between the two races:
In the comic canon we see a very wide range of human/Asgardian hybrids including Perseus, Andromeda and Vincent Von Doom. Some are descended from Thor (pure Asgardian) and some from Loki (Ice-Giant/Asgardian). The ability to crossbreed is definitely a strong sign of shared DNA.
Within the movie canon, in "Thor : Dark World", we see a range of portals opening and closing at random with no input from technology. This would suggest that for millions of years there has been cross-pollination and crossbreeding between the nine realms, to the point that a human can be infused with Asgardian DNA with no negative side effects.
How hybrids of the two species can only be explained by the use of Asgardian technology/magic because the physical differences between the two species should prevent anything that resembles cross-breeding impossible by normal means.
Asgardians have denser molecular structures, nearly three times that of a normal human. This along with their increased lifespans, improved regenerative abilities, vast amounts of superhuman strengths (an average male is capable of lifting 30 tons or 60,000 pounds) or the equivalent of an Abrams tank!
Where this extra genetic information for the Asgardians is stored (assuming it is even genetic) would make our two species incompatible unless technology or magic were utilized in the process.
Yes, the Marvel Universe is rife with demi-gods of Asgardian, Greek and other deities. This is NEVER explained in canon, so we are left to make assumptions that these deities facilitate and support the pregnancy of mortals for their own benefits.
As far as effecting Asgardians with electricity or particular medicines, we have to assume that SHIELD possessed information to create tools and medicines which could affect the Asgardians. No normal doctor should have been able to treat one, let alone sedate one. Medicines that affect humans MAY have a completely different effect, an increased one or ABSOLUTELY NONE AT ALL.
Thor has regularly lamented the difference between Asgardians and Humans and makes a great effort to restrain his powers lest he accidentally kill a human with a careless gesture. His strength is so much greater than his Asgardian breathren, the difference between his strength and the average Asgardian is the same as the difference between us and the average Asgardian. This comic panel explains this:
The cinematic Thor and Asgardians are also explained as completely different species in this Wiki entry:
While Asgardians and humans look the same in appearance, they are very much different. Asgardians have various superhuman abilities that are superior to a normal human being.
The most primary of their abilities is superhuman strength, although it varies while the average Asgardian possess strength to battle any type of being within the Nine Realms while more developed warriors, like Heimdall, the Warriors Three, Frigga and Sif have strength that is slightly superior in which they can overpower low-level Asgardian warriors (or in the case of Frigga, battle an Dark Elf to an remarkable degree).
Loki, while born as an Frost Giant but given some Asgardian "energy" by Odin while he was a child, has strength that would equal a well-conditioned Asgardian as the ones listed above and can almost match Thor, blow for blow. Only Bor, Odin and Thor seem to be the ones that possess the highest level strength due to them being the past, present and future kings of Asgard and the ruling leaders of their kind.
In the first movie, Thor was exiled to Earth WITHOUT his powers, so he's essentially mortal. It's why he was affected by Darcy's taser, and while in the hospital, the doctor was able to incapacitate him with whatever drug they used to knock him out. If he had his powers, neither would've happened.
Although it is true that Agardians have superior strength (among other things) to humans, in biology, even if through some advanced tech, if the progeny created from a union (say, an asgardian and a human) is fertile, i.e., can naturally bear children, then there is a very high chance they belong to the same species. In fact, this is the number one indicator that they are of the same species. If this is the case with human Asgardian hybrids, then if they are not of the same species, then they are still connected to each other greatly somehow.
If this Andromeda or Perseus (who have been mentioned by the first answer-er to this question) have ever had children with anyone (preferably with zero involvement of advanced biotech or magic), then that is evidence for the whole they're superhumans rather than "gods, whom we have little to nothing in common with".
One answer-er mentioned how humans and Asgardians couldn't crossbreed via "normal means"... That is not true. They can and they have. There have been Asgardians married to humans before because there is record of Asgardians looking for golden apples to prolong their spouse's lives. Even Thor mentioned wanting a golden apple for Jane for this purpose, and I'm pretty sure they cross bred via "normal means" all the time. Did I mention that Thor had a lot of "quality time" with many Earthen women, namely from Viking villages?
