Zombies, Klendathu and The Absurdly Violent Intergalactic Space Fungus.

[YorkNecromancer]

though I thought the Tolkien orcs were supposed to represent WW1 germans?

And that's the joy of applicability. It's both and neither at the same time.

Which people who like things to be either/or find utterly infuriating.

There's a cultural theory called [url=https://en.wikipedia.org/wiki/The_death_of_the_author]The Death of The Author[/url], which I personally subscribe to. It argues that, essentially, the viewpoint of the artist isn't really all that important when it comes to their work. Summarised quickly, it works like this:

Creator ---->intentions>-----> Art <------<perceptions<------Audience

The creator designs a piece of art with certain intentions: Tolkein wants LoTR to simply be a mythic story about war between good and evil.
The art, however, exists separately from the creator's desires, because once created, that's it - it's out there and cannot be modified further.
The audience then interact with the art, and bring their own cultural perceptions to the piece, thereby experiencing it differently based on their own experiences, worldview, religion, politics, etc...

So, a heroin junkie reads LoTR and in Gollum, sees an equivalent of their own experiences. Is this an allegory, designed intentionally by Tolkein? No. There is simply the applicable idea originated by the audience member.

These multiplicities of experience, where there isn't one YES/NO answer are part of the joy of art. To quote Neil Gaiman, consider a gem. If you tilt it just right, you see only one facet, one side of the gem, and it's beautiful - so beautiful you could imagine it being the entirety of the gem. But then you look at it from another viewpoint, and there's even more beauty that you missed because you were only looking at one facet of the thing.

Applicability means that whatever you see is valid, so long as you can justify why you're right, and a lot of people hate that, because it means that they have to hold conflicting, sometimes contradictory ideas in their head, which produces cognitive dissonance - they want there to be only one facet to the gem, one 'right' answer. Basically, the gem's many facets sparkle too brightly for their eyes to cope with.

But the gem remains a gem, no matter how much they might close their eyes, squint at the one facet they like, and argue otherwise. The creator brings their experiences, the audience brings theirs, and when the two meet: art.

[Charon]

Asexually reproducing organisms can still evolve, just slower than sexually reproducing ones. In the case of orks, they shed spores throughout their lives. An ork that is more skilled will live longer, survive more fights (I can't remember where but it is explicitly stated that orks shed spores much more intensely while fighting) and therefore shed more spores. If there are any biological inheritance their offspring will get some, and by having many more offspring they're out-competing their weedier rivals.

Why is nobody taking the fluff about the creation of the "Kork" into account?
The Korks" were created by the Old ones (aka Brain Boys) to fight the Necrons. It was a bioweapon unleashed yb them in the same way they created and unleashed the Eldar race against the C'Tan. They do not evolve. They just fight because that is the only reason they exist. They can not even stop anymore as their creaters (the ones holding their on/off button) have been destroyed.
Orks are the same age as the Eldar race (perhaps even older) and have not changed a bit since then. They can't be more than they are but at the same time they can not be less. Even the backwater Snakebite Orks have the knowledge to create Cyboars.

[Mr Mystery]

There's nothing to say Orks don't evolve though.

That they can Orkiform a planet reduces the need (much in the same way we've mucked up our own evolution by learning to adapt our environment, rather than adapt to it), as does the existence of Oddboyz (who always seem to know what to make and when).

From my reading of the Necron Codex, the Old Ones didn't just Tommy Cooper Orks, Eldar and Humans into existence. Instead, they found (or indeed founded, it's not massively clear) primitive races, and then engineered up from there.

[grimmas]

Well given that Homo sapiens are estimated to have evolved 200000 years ago and we are pretty much unchanged since. It's entirely possible given their biology that any evolution Orks do under go will be on a geological time frame.

Morgrim makes a good point about the Waaagh fields though. It's something they don't mention to much in the modern fluff but it was always a bit of a favourite of mine. PMA being an actual thing with Orks really tied in with their persona. I blame Sandy Mitchell letting Cain steal Ork guns and they still work for him.

[Psychosplodge]

they worked cause the Orks they were shooting at believed they worked

[Mr Mystery]

I'll allow it!

And anyways, it's not all Orky guns that don't actually work. Just some of them.

#notallorkguns

[grimmas]

Sounds legit.

[Morgrim]

Well given that Homo sapiens are estimated to have evolved 200000 years ago and we are pretty much unchanged since. It's entirely possible given their biology that any evolution Orks do under go will be on a geological time frame.

Humans are still evolving, but our rate of evolution has dropped dramatically since approximately the time of the industrial revolution, and was probably a little faster still pre-agriculture. That said, a lot of the more recent changes are less visible, with height being the only really notable modification.

If you want a big example of 'modern' evolution though take a look at blood types by proportion in different parts of the planet. You'll see that people of european descent have a significantly higher proportion of Type O blood compared to others, which is especially odd since O is actually a recessive trait. And the percentage of people with Type AB is tiny. (Although it's also the smallest globally, so that isn't as odd.) The reason for this skewed distribution? It's because the more receptors on your blood cells, the antibodies that make blood A or B or AB with both, the more vulnerable that person is to the Black Plague. If you were A or B, you'd have only a slim chance of survival. If you were AB you were definitely dead. If you were O you had a chance of surviving!

Within the space of 2 generations Europe went from having majority Type A to majority Type O blood, as an adaption to loosing a third of their population. There are also a couple of gene sequences for disease resistance that exploded across the population at the same time for the same reasons.

[grimmas]

Granted but I was more commenting on the time these things take for any noticeable effect. I thought the height change was more to do with improvement in nutrition of the last century rather than natural selection?

I'm AB positive I'll do my best to avoid the Black Death 😳 . Still I can use anyone's blood for a transfusion so it's swings and roundabouts

[Psychosplodge]

Avoid Eym...