It is true that it is possible for a population to not evolve for a while.
There is something called the Hardy-Weinberg theorem, which characterizes the distributions of genotype frequencies in populations that are not evolving.
There are 5 Hardy-Weinberg assumptions:
- no mutation
- random mating
- no gene flow
- infinite population size
- and no selection (natural nor forced).
You can see that some of these are kinda extreme and really hard to get, but with approximations, we can work.
For example, instead of an "infinite population size" we have enough with a really large population, such that genetic drift is negligible.
Concluding, yes, it is possible (but really difficult) for a population to not evolve for a while (at least, in nature), as long as the 5 assumptions above are met.
If you want to learn more, you can read:
brainly.com/question/19431143
