The Gene for Hands Also Codes for What?

 In this NYT article, "How Did Hands Evolve? The Answer Is Behind You.", scientists had discovered a strange connection between the stretch of DNA called 5DOM that had been found in both mammals and zebrafish. It was found by Dr. Duboule and his colleagues, who were looking at molecular locks that sat along 5DOM. They had snipped 5DOM out of the DNA of a mouse embryo, and it ended up developing legs, but not feet. This led to more questions about when this section of DNA came about in animals, so Christopher Bolt, a graduate student at the time, looked through the zebrafish's genome and found 5DOM there too. This suggests that this set of genes was also present in the primordial ancestor of zebrafish and mammals.

 Dr. Hintermann took over the research and, using CRISPR, removed the 5DOM molecular locks from zebrafish embryos. The deletion didn't have much of an effect on the development of fins, but it did affect the development of the cloaca. When looking back at the same area in mouse embryos, the researchers discovered that the sequence codes for the urogenital sinus in mammals. Scientists are proposing that 5DOM went through evolutionary change, since it is easier to recode than to build a whole new sequence. Both structures that form are extremities that developed towards the far end of the body as well. There is more research needed on exactly why this change in 5DOM came about, but this is a starting point.

 Researchers are slowly finding more pieces of how the different gene codes for mammals came about with the shift onto land. This discovery at least gives a jumping point for how connected animals are and where mutations could have taken place in DNA, or how adapting to environments could have played a role in this.