to evolve
'To improve' means 'sudharana'.
She gradually made her way up the beach. -V.Cain Gradually means to progress, but to progress slowly. -V.Cain
"Crescendo", means to gradually increase in size, intensity or force.
One word that fits is corrosion.
Eugenics is the word that means movement to improve the human species through selective breeding or other processes.
Its called weening
progress
Progress.
Slow or improve
Fade or melt would fit.
Improve