Hey there @Subotai_Archer_Thief. I am not sure what platform or mode you play on, but if you have access to the Admin Panel I may be able to help you. In the ‘Purge’ settings sub-menu, change the Purge Level setting to 4 in order to maximise your chances of a human Purge. Settings of 5 or 6 will only yield animal purges. You could also adjust the Purge Meter Trigger Value setting to alter the frequency, with lower number values leading to more frequent purges. Sort of like this:
Although I wouldnt go as low as 2000 or there will be little break inbetween. Say 12,000-16,000 is a nice ballpark figure for me, but it all comes down to personal preference. Here is a link to a good thread where we discuss the settings in greater detail. If you have any further questions, Subotai then please feel free to ask.