He makes a few assertions that are uncertain however. He seems to emply tribes weren't closely genetically related when in all likely hood they were made up of a mere handful of breeding pairs that were intermarrying. The scale of tribes and groups is probably greatly overstated and it is doubtful in most situations if they numbered more than a few hundred individuals back when tribalism was actually practiced. These cosmopolitans are too used to living in places like jew york with millions of people crammed together.