An a.i. clarification of the article’s summary: Researchers proved that stem cells from mammals can turn into any cell type like cells from an early embryo. These are called naive stem cells. They’ve shown naive stem cells work great in rodents, but not as well in primates since the donor cells don’t match the host embryo. So they tried different conditions to produce naive stem cells from monkeys and got better at growing chimeric embryos. A chimeric monkey is one that has cells from two different embryos combined together. They created an aborted fetus and live chimeric monkey with high donor cell numbers. Testing showed the donor cells integrated into many tissues (including sex organs and placenta) of the chimeric monkeys, up to 90%. This is a big deal for researching naive stem cells and genetically modifying primates.