Modern gene-editing tools are being used to understand the mechanisms of evolution.
Some call it the chickenosaurus, others the dino-chicken. Whatever you term the proposal to transform a chicken into a creature more like its dinosaur ancestor, it is having its scientific moment.
Researchers have succeeded in making the feet, limbs and face of unhatched chicks a bit more like those of the creatures’ 150-million-year-old ancestors by tinkering with the molecular pathways that forge these structures. The goal is to comprehend the molecular events responsible for one of the most awe-inspiring transitions in the fossil record.
The field of evolutionary developmental biology — evo-devo — is full of such creations: from mice with longer, bat-like limbs to fruit flies with torsos segmented like beetles’. But until now, the brute tools used to create these creatures have been imperfect.
This is about to change. In a paper published online on 17 August, a team used CRISPR–Cas9 to inactivate the genes involved in zebrafish development, resulting in fin tips more like the feet and digits of land vertebrates (T.Nakamuraetal.Naturehttp://dx.doi.org/10.1038/nature19322;2016). Other recent CRISPR experiments have tinkered with butterflies to learn how they see more colours than flies do, and done away with crustaceans’ claws to understand the origin of these specialized appendages.
So far, the edits have tended to simply inactivate genes. But evo-devo scientists will soon start swapping genes between distantly related beasts to learn the origins of adaptations such as multicellularity and the anus, to name but two problems troubling the field. Our ability to access and analyse ancient DNA means that we can now insert genes from extinct animals into the genomes of their living relatives.
These sorts of experiments could draw evo-devo fancifully close to de-extinction, the quest to resurrect woolly mammoths and other long-dead animals. But every upturned urinal is not a Dadaist masterwork, and the idea behind the experiments is what matters. These ‘hopeful CRISPR monsters’ could confirm or reject decades-old theories about key events in evolution, and help us to come up with new ones.
Just think of what we could learn from a bona fide dino-chicken.
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CRISPR helps evo-devo scientists to unpick the origins of adaptions. Nature 536, 249 (2016). https://doi.org/10.1038/536249b