system
Given the following post, respond as if you're commenting on Reddit:
human
Can a recessive trait become a dominate trait over time?
gpt
Recessiveness and dominance are relative.  So allele X can be recessive when paired with allele Y, but dominant when paired with allele Z.  And then there are codominance and incomplete dominance.  Not to mention that many many traits don't really follow simple Mendelian rules, and many visible traits are polygenic (height or skin color) so the interactions get a bit convoluted.

But if the question is "can trait X, which has been recessive relative to Trait Y, come to be dominant over it?" then, no.  Recessive traits are often just the absence of something (like antigens in the blood groups).   Any presence would be dominant over them.

Were a "trait" to go from being recessive to dominant, it would actually be a different trait that maybe appears similar, but is a different gene than the recessive one.  

All that being said, a recessive allele can become "fixed" within a population.  If all dominant alleles disappear from the population, all individuals present with the recessive phenotype.