Psychologist david katz developed the of attitudes.

David Katz was a Swedish psychologist and educator, born in Germany. He made research and experiments in the field of visual and tactual perception, motivation, and animal and child behavior. 
Psychologist David Katz developed the neoclassical theory of attitudes. He is primarily remembered for his application of the phenomenological method to experimental psychology.

new ideas form the base for the growth of the people.each time they try to develop, they may discover a new form or abilities of themselves this makes the people satisfied in living their life in a happy way.this makes sense that new ideas of people cn change their live.the ideas, if bring their best, they will be changing their present state.

During the paleolithic, hominins grouped together in small societies such as bands, and subsisted by gathering  plants  and fishing, hunting or scavenging wild  animals. the paleolithic is characterized by the use of knapped stone tools, although at the time humans also used  wood  and bone tools.