Question: People often say, including those with extensive knowledge in biology, that a certain species of animal will evolve in one way or another:

1. From changing environments.
2. Mutations.
3. Possibly even genetic engineering from human animals.

My question lies in the fact that, aside from the latter option, why haven't any differences in animals'(except humans) markup, morphology, intelligence, DNA, behavior, or any habits changed over thousands or (possibly millions) of years?

A cockroach has had the same behavior it has today [more than 10 million years ago](http://en.wikipedia.org/wiki/Cretaceous), and there have been no advancements in the species in the slightest bit. 

It makes you question evolution, because why don't other animals (like cockroaches) have any changes over 10+ million years, yet humans, like me and you somewhat, have, in a relative period of time similar to the linked geological period above, evolved from spear tossing hominids into someone brilliant enough to even ponder this question.

If modern humans are the result of mutations in genes, why has no one species over the course of hundreds of millions of years been fit enough, or advanced mentally as we have, or even in any slightest bit?

Answer: 
> 
> How come most animals never seem to evolve over millennia?
> 
> 
> 

The word "seem" in your question should not be disregarded. You seem to assume that cockroaches (or most animals as you say) did not change much the last tens or hundreds of thousands of years. But what do you know about that (no offence here)? Have you actually reviewed many kinds of research that estimate the rate of evolution of different randomly chosen lineages in the past 500,000 years? I think you assume that other species evolved slower than humans rather than know it. And you will certainly put much more importance to the evolution of the gene FoxP2 (involved in language) than to a gene allowing cockroaches to have a better sense of smell. This is a biased view of what is a rate of evolution. It would be much wiser to consider a rate of evolution as something like the number of newly arising mutations that succeeded to get fixed in the population. See Haldane's rate of evolution and the Darwin unit. Please don't make the mistake to think that being smart (or complex) is some kind of the goal of evolution and those that are not smart (or complex) are "less evolved" or that they evolved more slowly.

You also seem to want to point on the evolution of DNA and evolution of habits. I guess you might be appreciative of the evolution of human knowledge and culture. But this is obviously something that does not have to do with genetic evolution but is rather a matter of cognitive capacity. You cannot compare the change of culture and traditions of insects and humans as insects have mostly no traditions.

Now, this is obviously true that different lineages evolve at different rates. Many things influence this rates such as the population size, the mutation rate, the generation time, the selection pressure (which itself might depend on social structure or the rate of environmental change for example). In these terms, I would rather believe of Homo sapiens as a lineage that should have a rather slow evolutionary rate.

Homo sapiens is quite a recent species. And speciation is often linked with phenotypic divergence, with niche competition and niche complementarity and therefore with a high rate of evolution. In these terms, I would believe that humans are a lineage with high evolutionary rate.
> 
> aside from the latter option, why haven't any differences in
>  animals'(except humans) markup, morphology, intelligence, DNA,
>  behavior, or any habits changed over thousands or (possibly millions)
>  of years?
> 
> 
> 

What evidence is leading you to that conclusion? For horses, example. (From the talkorigins article):

> 
> The first equid was Hyracotherium, a small forest animal of the early Eocene. This little animal (10-20" at the shoulder) looked nothing at all like a horse. It had a "doggish" look with an arched back, short neck, short snout, short legs, and long tail. It browsed on fruit and fairly soft foliage, and probably scampered from thicket to thicket like a modern muntjac deer, only stupider, slower, and not as agile. This famous little equid was once known by the lovely name "Eohippus", meaning "dawn horse". Some Hyracotherium traits to notice:Legs were flexible and rotatable with all major bones present and
>  unfused. 4 toes on each front foot, 3 on hind feet. Vestiges of 1st (&
>  2nd, behind) toes still present. Hyracotherium walked on pads; its
>  feet were like a dog's padded feet, except with small "hoofies" on
>  each toe instead of claws. Small brain with especially small frontal
>  lobes. Low-crowned teeth with 3 incisors, 1 canine, 4 distinct
>  premolars and 3 "grinding" molars in each side of each jaw (this is
>  the "primitive mammalian formula" of teeth). The cusps of the molars
>  were slightly connected in low crests. Typical teeth of an omnivorous
>  browser.
> 
> 
> 

So from that, you conclude that the DNA, morphology, and intelligence of horses hasn't changed at all in 50 million years?