When it comes to the woolly mammoth, however, that rule has now been bent. It’s been 4,000 years since the eight-ton, 12-foot, elephant-like beast walked the Earth, but part of its DNA now operates ...

The zygote inherits two fully active X chromosomes and begins re-inactivation of the paternal X chromosome (XP) at the 4- to 8-cell stage. In the trophectoderm (extra-embryonic cells, shown in ...

Relying on CRISPR, they then took both the stem cell and zygote approach to rewriting the mouse’s stem cell to express those traits. The next steps involved more than a little hit and miss.