To study evolutionary morphings, scientists often look at teeth, which are well preserved and thus well represented in the fossil record. But scientists can do more than observe the traces left behind by extinct species. They can actually experimentally reproduce evolutionary shifts that occurred millions of years ago. Typically, these shifts are induced in embryonic development. As it turns out, embryonic development may be so tuned as to recapitulate evolution. In fact, in a recent study, scientists obtained teeth similar to those that enabled the gnawings of extinct species, creatures that separated from the ancestors of modern mice as far back as the Triassic.
This study was conducted by researchers representing the University of Helsinki and the Universitat Autònoma de Barcelona (UAB). They investigated whether gradual alterations of tooth development could produce gradual changes in the phenotype, and whether these changes could reflect known evolutionary transitions.
The details of the study appeared July 30 in Nature, in an article entitled, “Replaying evolutionary transitions from the dental fossil record.” The article described how the researchers used mice that carried a spontaneously occurring null mutation in ectodysplasin (Eda). This mutation, the researchers said, was chosen because the effects of Eda on tooth morphology are relatively subtle, simplifying dental morphology without causing a complete loss of teeth. Yet the Eda mutation also alters many morphological characteristics, and is thus highly informative.
Read the full, original story: Evolution’s second bite: Primitive teeth from fresh embryonic culture