How is man warlike by nature?

Depends on the age of the man

Male adolescence is delayed, well females get there first, to ensure
that males are able to survive, spot of diversion tactics.

Answer :-
 between 7 and 14, very warlike, but physically immature
 between 14 and 28 a menace

After that it is largely self protection.

We are little more than animals, but that 'little' is handy.

this doesnt tell how man is warlike by NATURE

Maybe man is NOT warlike by nature, just defends his turf.

If this is the topic for homework of some kind, G-A does not approve
of answering such questions and may delete them.