Crows can recognise human faces like mammals

Crows have the ability to recognise faces and associate them with negative, as well as positive, feelings, according to a new research.
Researchers from the University of Washington found that the brain pattern in crows was similar to those seen in mammals.
"The regions of the crow brain that work together are not unlike those that work together in mammals, including humans. These regions were suspected to work in birds but not documented until now," John Marzluff, lead researcher, said.
"For example it appears that birds have a region of their brain that is analogous to the amygdala of mammals. The amygdala is the region of the vertebrate brain where negative associations are stored as memories," he said in a statement. 
"Previous work primarily concerned its function in mammals while our work shows that a similar system is at work in birds. Our approach could be used in other animals - such as lizards and frogs - to see if the process is similar in those vertebrates as well," he added.
Twelve adult male crows were captured by investigators all wearing masks that the researchers referred to as the threatening face.
The crows were not treated in a threatening way, but the fact they'd been captured created a negative association with the mask they saw.
Then for the four weeks they were in captivity, they were fed by people wearing a mask different from the first, this one called the caring face.
The masks were based on actual people's faces and both bore neutral expressions so the associations made by the crows was based on their treatment.
The team injected a glucose fluid commonly used in brain imaging into the bodies of fully alert crows that then went back to moving freely about their cages.
The fluid flooded to the parts of the crow brains that were most active as they were exposed for about 15 minutes to someone wearing either the threatening or caring mask.
The brain pattern of the crows showed that the caring masks stimulated brain areas linked to reward, while threatening masks activated regions associated with negativity.
The study will be published in the Proceedings of the National Academy of Sciences.