Fionnáin quoted The social behaviour of monkeys by Thelma Rowell (Penguin education)
When I am asked why monkeys live in groups, the first answer that comes to mind is 'because they like each other's company' – and that is probably a better answer than many more seemingly sophisticated answers that have been offered like 'sexual attraction'.
— The social behaviour of monkeys by Thelma Rowell (Penguin education) (Page 174)