Adaptation takes a long time because the [[1]] factors of a region change very slowly. 

Adaptation takes a long time because the abiotic factors of a region change very slowly. 

Adaptation is defined as the process where a species or an organism gradually becomes better acclimated to its environment.

It is a very slow process as it is dependent on the abiotic environment (light, dark, temperature, water, wind), but also on the complex biotic environment (other organisms such as mates, competitors, parasites, predators, and escape tactics of prey). As the abiotic factors do not show any drastic change hence, the adaptations are slow.