VESTIGIAL GENES. “What atavisms tell us is that what evolution has put away, development can quickly restore. Switches that turn off gene expression can turn back on, and hence these evolutionary remnants reveal the dynamic interplay between “ontogeny and phylogeny” that Gould expounded on.”
https://evolution-outreach.springeropen.com/articles/10.1186/s12052-014-0012-5