According to ScienceNews, in an article by Laura Sanders, scientists have made embryos that are a lot mice, but a bit human. Human cells don't really grow well with other animals, but in a new mice embryo, 4 percent of it was human cells. From all the trial and errors, scientists came down to the fact that time played a crucial role. Human stem cells' development clocks must be turned back to an earlier phase known as the naive stage. "Feng and his colleagues reset the stem cells’ clocks by silencing a protein called mTOR for three hours. This brief treatment shocked the cells back to their naïve stage, presumably restoring their ability to turn into any cell in the body." These youthful stem cells were injected into the mouse embryos where the human cells knitted themselves into the developing tissues of the mouse. This eventually let to become the liver, heart, bone marrow and a bit of the brain. I think this article was very interesting as this could give rise to more advancements in science. To be more specific, this could help us study diseases and give a source to human organs.