Antibody from violent offenders makes mice aggressive

Mice injected with a chemical taken from the blood of criminals took on characteristics of murderers, rapists and gang members.

Mice got aggressive when injected with antibodies from violent offenders. Picture: Alamy.

One day, in a laboratory in Norway, scientists injected mice with a chemical taken from the blood of criminals — and the mice turned mean.

As the proteins coursed round their rodent brains, they seemed to inherit the impulses of the murderers, rapists and gang members who provided them.

They were quicker to start fights when provoked, and took just a quarter of the time to deliberate before leaping on intruders.

Now scientists think this chemical, an antibody which is involved in the human stress response, may give a clue as to what makes humans aggressive too — although they said it remained a mystery exactly what it does.

For the study, published in the journal Proceedings of the National Academy of Sciences, researchers extracted the antibodies from 16 violent offenders imprisoned for murder or extreme physical or sexual assault.

The scientists were interested in the antibody which interferes with the production of cortisol, a stress hormone. The “criminal” antibody bound to hormones in a reliably different way to the one taken from the non-criminals. The biggest difference came when it was injected into the mice and an intruder was then put in their cage. “The resident would attack the mouse very fast,” said Serguei Fetissov, from Akershus University Hospital. The implication was that this antibody, which differed between violent and non-violent humans, could be one of the reasons they were violent in the first place.

“The antibodies may predispose people to aggressive behaviour,” said Professor Fetissov. “But we don’t know why the antibodies differ in these groups.” He stressed that a far bigger sample was needed to make firmer conclusions or to understand the mechanism before anyone considered using this as an intervention to, for instance, “cure” violent offenders.

It is highly likely that many people in the general population have these antibodies and are not violent at all.

The Times