In a recent study published in the scientific journal of Neuroscience, a group of scientists regale their journey to try and use CRISPR gene editing technology to bio-engineer an extra-friendly and extra-chill hamster.
Like a good bad sci-fi film, this went horribly, horribly wrong (emphasis mine):
We produced Syrian hamsters that completely lack Avpr1as (Avpr1a knockout [KO] hamsters) using the CRISPR-Cas9 system to more fully examine the role of Avpr1a in the expression of social behaviors. We confirmed the absence of Avpr1as in these hamsters by demonstrating 1) a complete lack of Avpr1a-specific receptor binding throughout the brain, 2) a behavioral insensitivity to centrally administered AVP, and 3) an absence of the well-known blood-pressure response produced by activating Avpr1as. Unexpectedly, however, Avpr1a KO hamsters displayed more social communication behavior and aggression toward same-sex conspecifics than did their wild-type (WT) littermates.
In other words, the researchers used CRISPR-Cas9 to remove a naturally occurring hormone (vasopressin, and its receptor, Avpr1a) that is typically expected to regulate things like teamwork and bonding. Their hypothesis was that, by removing this hormone, the hamsters would stop regulating their friendliness, and just give in to being cuddly and adorable bosom buddies all the time. But in fact, in had the opposite effect: they were incredibly aggressive, territorial, and violent towards other hamsters of the same sex.
CRISPR-Cas9 editing of the arginine–vasopressin V1a receptor produces paradoxical changes in social behavior in Syrian hamsters [Jack H. Taylor, James C. Walton, Katharine E. McCann , Alisa Norvelle, Qian Liu, Jacob W. Vander Velden, Johnathan M. Borland, Michael Hart, Chengliu Jin, Kim L. Huhman, Daniel N. Cox, and H. Elliott Albers / Neuroscience]