Russian scientists proved that lower apes – rhesus monkeys and capuchin monkeys – are able to operate with the idea of value.
      
      The ability to set relative characteristics of various items and to generalize appears to be found not only in human beings, but in some animals as well. No doubt apes have said ability and even crows do, which may sound striking.
      
      Russian biologists tried to develop the ability to distinguish geometrical figures by their size in monkeys.
      
      20-30 attempts turned out to be enough for young monkeys to tell the difference between figures of different sizes. Adult animals learned even faster.
      
      Source: Informnauka