This is a super interesting article written by a neurobiologist BUT what really got me and the reason why I am posting here in the health section is that they keep on finding a link between loneliness and the immune system - something that I have been harping on for ages and ages when it comes to leaving a parrot all alone for hours and hours and hours every single day! Parrots NEED companions! The other is the relation between biology and behavior (pay attention to the bit that says that nerve fibers in our skin react to touch with a pleasant sensation and that the most acute is when the stroke resembles that of a mother caressing her newborn) which supports my theory that 'speaking their body language' that is, imitating what a parrot would do to another parrot is the best way to make them feel secure and loved.
https://www.nytimes.com/2020/01/28/book ... worth.html