it seems animals know what their body need, so they eat things normally are not part of their diet, e.g., African elephants go into caves and mind rocks once in a while to get mineral supplement; red deer in Scotland would kill birds and chew the heads for minerals; and also many animals migrate to find minerals.

People may heard stories that some young children have the "weird" behavior, eating dirt or some other strange staff. However, their doctors probably will say the diet of these kids lack certain minerals.

It seems both animals and young children know what their bodies need, and then will find them and add to their diet. As adult human, it seems we've lost this capability and have no idea what our body really need. We only eat what taste good, except when we are hungry and thirsty. We don't know what our body need, unless or until our doctors tell us.

Do animals or young children really know what they need and then go to find and eat, or they have developed a sense that the lacked minerals will appeal to them in some certain way?