TWO DIFFERENT KINDS OF HIERARCHIES

Key idea: The cells in a human (or other multicellular organism) are specialized parts in a cooperative whole. The concept of a hierarchy can help to clarify this arrangement of specialized parts working together in a cooperative whole.

Hierarchy of Importance

A hierarchy is a system of ranking things according to how important they are or how inclusive they are.

One example of a hierarchy of importance (in the sense of decision-making authority) might be the army. Here’s a SIMPLIFIED version of the hierarchy of army officers. Try placing the the symbols in the correct position on the pyramid to demonstrate which officers have higher and lower ranks.

• General (star)
• Colonel (eagle)
• Major (leaf)
• Captain (double bar)
• Lieutenant (single bar)

Turn and Talk:

You could also write out a hierarchy of human needs. Perhaps you would put food and shelter higher than, say, video games. Where would you put love and friendship? How you answer might depend on your values or the purpose of the hierarchical list. We’re using the word importance here as a verbal bucket for all sorts of different ways of valuing things. A hierarchical listing of terms might change depending on what kind of importance you want to think about: authority? usefulness? social status? financial cost? moral value?

Hierarchy of Inclusiveness

Besides hierarchies of importance, there are also hierarchies of inclusiveness. A hierarchy in this sense can help keep track of which things are grouped inside of other things.

Think about a tree.

A tree includes its branches and leaves. Branches include leaves, but do not include the whole tree of which they are a part. Leaves don't include branches or trees. So "tree" is at the top of this hierarchy because it is the most inclusive of the three things.

The tree is whole, the branches are parts, and the leaves are even smaller parts.

Confused? Here are some starter diagrams (pending) for you.

Some hierarchies are complicated.

If we included the term “forest” in the list, where would it go?

Would we still think of the term “tree” as whole in that new list?

Sometimes it can be unclear whether a hierarchical list of terms is a hierarchy of importance, a hierarchy of inclusiveness, or both. Are trees more important than leaves? Well, without leaves, a tree will eventually die (because it can’t capture sunlight and get energy to live). On the other hand, if  one leaf on a tree dies, the tree can live; but if the tree dies, all its leaves die. Hmm. And generals may be more important than people with lower ranks in certain ways, but an army with only generals wouldn’t be much of an army.