Cereans Are an Alien Race Living on a Distant Planet

Cereans are an alien race living on a distant planet called Alderaan, whose bodies function the same way as humans' bodies do.A galactic scholar has been learning about the Cereans' evolutionary history.The following is an excerpt from the scholar's work:
The Cereans first appeared approximately 50,000 years ago.Throughout their evolutionary history, they have lived in a region on Alderaan that gets very little sunlight, resulting in very little exposure to ultraviolet radiation (UVR).The Cereans have never migrated elsewhere.Approximately 10,000 years ago, they discovered a food source that provides an ample supply of Vitamin D for their dietary needs.
Based on this scholar's work, draw a line graph that approximates the expected relationship between the Cereans' evolutionary history, starting with -50,000 (meaning when Cereans first appeared) and ending at 0 (meaning now), and their skin tone (a smaller value means lighter skin tone; a higher value means darker skin tone).