How can I gain humanity in Dark Souls?

From (one of) the Dark Souls wiki:

• Humanity can be earned by playing as a Phantom, and help kill the end-level boss.
• Humanity can be earned by killing Evil Spirits (invading players), or by invading and killing a player in another world.
• Humanity can be bought from some merchants.
• Humanity can be found, as a dropped item, from some killed enemies.
• Humanity can be found as a consumable item.
• Humanity can be earned by having your hint sign up-voted by another player.
• Humanity can be earned by killing a large amount of monsters in one area if the boss is alive (up to 10 Humanity).

The last reason must be why I was gaining humanity when spawning.