For the first time in history, scientists have created an early-stage embryo that is half-human, half-ape.

Medical journal Cell published the findings, which showed an image of the early-stage chimeric embryo with cells of different species origins, as pictured above. Scientists used fluorescent antibody-based stains, where the red color indicates human cells. While the embryos were created to see if new ways could be found to produce organs for people on transplant lists, not everyone in the science community is supporting the idea.  Kirstin Matthews, a fellow for science and technology at Rice University’s Baker Institute, is one of those people. She told NPR:

 “My first question is: Why? I think the public is going to be concerned, and I am as well, that we’re just kind of pushing forward with science without having a proper conversation about what we should or should not do.” 

Co-author of the Cell study, Juan Carlos Izpisua Belmonte, defended the experiment, stating, “This is one of the major problems in medicine — organ transplantation. The demand for that is much higher than the supply.”

Insoo Hyun, a bioethicist at Case Western Reserve University and Harvard University, also supported the study, stating, “I don’t see this type of research being ethically problematic. It’s aimed at lofty humanitarian goals.”

This isn’t the first study of its kind that some people would argue is controversial, as researchers have been injecting human stem cells into sheep and pig embryos to see if they would grow human organs for transplantation. Those experiments have failed, which led Belmonte to team up with researchers in China, where they took induced pluripotent (iPS) stem cells from humans and injected them into embryos from macaque monkeys. After one day,  human cells were detected growing in 132 of the embryos, and researchers were given 19 days to study them. Belmonte quelled fears of creating a new creature, stating, “Our goal is not to generate any new organism, any monster. And we are not doing anything like that. We are trying to understand how cells from different organisms communicate with one another.” He stressed that his team has no intention of even trying to grow human organs in such a closely related species.