Sandwiched between the sea lamprey and the axolotl on evolution's vast timeline — about 400 million years ago — another vertebrate appeared on the scene with the ability to regenerate an impressive variety of different tissues: the zebrafish.
At its base, vertebrate regeneration requires a complex molecular crosstalk between cells, similar in many ways to the cellular "communication" that occurs in the development of an animal from a single cell to an adult organism.
By studying how the retina develops in zebrafish embryos, Morris says, researchers can learn a great deal about how the process works in mammals, and specifically in humans.
An oft-repeated maxim in biology classrooms is that "regeneration recapitulates development." So, if our retinas are so similar in their development, how is it that zebrafish can regenerate retinal cells and we can't? The answer is suspended between between two distinct possibilities.
It’s sort of like the kid-in-the-dinosaur-museum thing." Smith also works closely with Stephen Randal Voss, sequencing the genome of salamanders, an amphibian group that veered off our common vertebrate path about 300 million years ago.
Though we share many of the same genes, the salamander genome is massive compared to our own — about 10 times as large.