Some new research out of Spain suggests psychopaths might be more prevalent than we currently think.
In a meta-analysis of existing research, which involved 16 samples of adults totalling 11,497 people, the researchers concluded “the prevalence rate of psychopathy in the general adult population at 4.5%” or perhaps as high as 5.4%. This is much higher than the standard 1% figure I found in existing literature while writing the book. The samples of participants came mainly from the USA.