From Popular Mechanics:
Researchers from Germany's Max Planck Institute of Molecular Cell Biology and Genetics in Germany and Japan's Central Institute for Experimental Animals introduced a specifically human gene, ARHGAP11B, into the fetus of a common marmoset monkey, causing the enlargement of its brain's neocortex. The scientists reported their findings in Science.
Those findings include a good indication that the ARHGAP11B gene played a key role in the development of the human neocortex, and, by extension, human evolution overall. (A 2015 study saw similar results with ARHGAP11B implanted in mice embryos, which "produced many more neural progenitor cells and could even undergo folding of their normally unfolded neocortex.")
In a press alert, the scientists behind the study were careful to specifically refer to their subjects as "transgenic non-human primates," which differentiates them from transgenic common marmosets, or humans (we're not given a cool classification for the sake of objectivity). They also included this ethical caveat:
We confined our analyses to marmoset fetuses, because we anticipated that the expression of this human-specific gene would affect the neocortex development in the marmoset. In light of potential unforeseeable consequences with regard to postnatal brain function, we considered it a prerequisite – and mandatory from an ethical point of view – to first determine the effects of ARHGAP11B on the development of fetal marmoset neocortex.
So, we're still a little ways away from a horrible interactive Planet of the Apes remix. That's good.
Somewhat related: I re-read Karen Joy Fowler's award-winning fiction-about-science novel We Are All Completely Beside Ourselves this summer, which I think every human being should read if they have not yet.
Uh-Oh, Scientists Used Human Genes to Make Monkey Brains Bigger [Tim Childers / Popular Mechanics]
Human-specific ARHGAP11B increases size and folding of primate neocortex in the fetal marmoset [Michael Heide, Christiane Haffner, Ayako Murayama, Yoko Kurotaki, Haruka Shinohara, Hideyuki Okano, Erika Sasaki, and Wieland B. Huttner]
Human brain size gene triggers bigger brain in monkeys [EurekaAlert!]
Image: Public Domain via Wikimedia Commons