Answer:
Genes on the Chromosome and Genetic formation.
Step-by-step explanation:
What is a chromosome?
Is a structure of nucleic acids that can be found in nucleus that carries the genetic formation.
When did the sense of smell evolve?
200 million years ago.
What might be an advantage to smelling?
Smelling can allow us to identify food and many more...
Hence, the cause of the evolution of smell is because the chromosomes and the genetic formation.