What factor does jared diamond propose to explain this isolation of various groups within the americas? explain

he would based it upon geographic luck which he often resulted his faith in.

although world war i began in 1914, the united states did not join the war until 1917. the additional firepower, resources, and soldiers of the u.s. to tip the balance of the war in favor of the allies. remaining neutral. when war broke out in 1914, the united states had a policy of neutrality.

is there multiple