I am currently working on a post-apocalyptic world where roughly 90% of humanity get infected by HDD (Human Degenerative Disease). HDD causes the human brain, glands and tissues to change quite dramatically. Reducing the majority of the infected to a feral state in which they are no longer sapient, but can be trained (with effort) similarly to gorillas, chimpanzees and dogs. The infected breed true among themselves, seem to have no memories of their past lives, and over the past 50 years have propagated a great deal. An immune or uninfected person who breeds with one of these new ferals has a 75% chance of producing non-feral offspring.
I am wondering what sorts of behavioural traits these ferals would be likely to exhibit and adopt?
Thanks in advance. Just let me know if this needs to be narrowed down further.