Analysis of the nematode gene ced-9 and the human gene bcl-2 has revealed extensive DNA sequence similarity, as well as functional similarity. They both control programmed cell death. Therefore, the ced-9 gene in C. elegans and the bcl-2 gene in humans are homologs. When scientists transfer a cloned human bcl-2 gene into a C. elegans embryo with a loss-of-function mutation in ced-9, cell death is prevented. What does this tell you about ced-9, bcl-2, and apoptosis in the context of evolution