किस प्राचीन दार्शनिक ने प्रसिद्ध रूप से कहा था कि 'मनुष्य एक सामाजिक प्राणी है'?

In which landmark text published in 1848 by Karl Marx and Friedrich Engels was the foundational theory of Scientific Socialism propounded?

The theory of historical materialism was propounded by whom?

What did Karl Marx predict would eventually happen to capitalist societies?