system
Given the following post, respond as if you're commenting on Reddit:
human
[WH40K] Have humans notably evolved since 2K? All humans, not just abhumans or the ocasional psyker.

And what *is* humanity's ultimate end? Will everyone become God Emperors at some point, space marines? Malcior style psykers?
gpt
In the aggregate? Not really. Your average Human in 40k would be virtually identical, at least genetically, to those in the 2nd millennium. 

That being said, we have three major "branches" off of mainline Humanity that are debatably unique and separate from normal Humans. 

First, you have mutants. While mutation was never a particularly unheard of phenomenon, it is something that has become much more of an issue. This is likely due to the huge difference in environments that people can be exposed to, often over generations. Back in M2 most mutation was at least survivable, if not treatable. Nowadays, mutants can be fully-realized, barely Human abominations that are hardly capable of rational thought. Not all of them, but enough to warrant caution. 

Second, you have Psykers. As the Warp has become more active over time, Humanity has found that our natural connection to the Immaterium (what some may consider the soul) has, in turn, become more active. Instead of simply depositing emotion and experience into the Warp, as had previously been the norm, some were finding that they could exert force on the material universe through what seemed to be sheer willpower. Whether or not this phenomenon has a basis in genetics is unknown, but it is clear that as the Warp has evolved, so has our connection to it. 

The third, and more debatable group are what we might call "post-humans". These include people like Space Marines, many in the Mechanicus, and a non-insignificant number of the more privileged elite. These people are technically Human, but have been so altered through technological augmentation that to throw them in with the rest of "standard" Humanity isn't quite right. The reason this branch is debatable is because it isn't a naturally propagating phenomenon. Space Marines are constructed more than they are raised. The Mechanicus replace and augment over time due to convenience or necessity, as do many in the Imperial elite. None of what makes them unique will be passed down through children, assuming, of course, that these people are even capable of reproducing naturally. 

The TL;DR here is that evolution doesn't have an "ultimate end"; it just **is**. In the last 40ish millennia, at least genetically speaking, there hasn't been a lot of development. Maybe people are taller on average, or maybe there aren't any more unibrows, or maybe finger nails have gotten thicker, but there's nothing that would stop you from procreating with them. They're still human, with virtually the same genetics.