There is a long history of debate about the amount of primary emotions people have. E.g. Paul Ekman in a study of 1972 suggests that there are 6 primary emotions: anger, disgust, fear, happiness, sadness, and surprise. And his authority made this amount of basic emotions a standard for some time. However, other scientists offered other amounts of basic emotions. E.g. Robert Plutchik in his concept of the wheel of emotions offers to consider 8 emotions to be the basic ones, adding trust and anticipation to the Ekman’s list, plus substituting happiness with joy.
As the scientists advance their methods and the science of emotions becomes less speculative, there is a tendency to shrink the amount of emotions that serve as the basis for the rest. Reviews and statistical processing of hundreds of fMRI and PET neuroimaging studies nowadays name five basic emotions: anger, fear, sadness, happiness and disgust, with this amount gradually becoming the new standard.