Now, against humans... people that pick a Civ with unique military units that require low tech usually have a tendency to declare war early, since those units w

Now, against humans... people that pick a Civ with unique military units that require low tech usually have a tendency to declare war early, since those units will provide them with early advantage. Now, war drives your happiness down and production/science goes down with it. Declaring war early might not be a very good strategy unless you know very well what you are doing. Like ganking a civ that everyone is in war with.