The diversity and complexity we see in the world around us can be reduced to a hundred or so building blocks. People, skyscrapers, algae all draw on the same set of chemicals. What makes us different at that level is the type, number and combinations of those physical elements.

Centuries ago, humans were thought to be of a different order because our basic ingredients came from a sphere of elements not available to other living beings or inanimate things. Now we know that we share the same chemical resources. As a result, we must ask different questions about our identity. In what ways are we different from other species? Are we different indeed? Does this difference matter? If so, what are the privileges and responsibilities we carry in this position?

These are tougher questions than people faced in the past. They had a more clear-cut sense of the role and place of humanity in the greater scheme of things. Our knowledge must be integrated into our way of understanding these matters. We will have to ask questions that they never thought of asking.

It helps, too, to keep in mind that we are only considering this matter on a purely physical level. Just as a stop light can be explained at the level of atoms and electrons, electricity and colours, signals and communication, so we need to think about higher levels of explanation of our humanity. Chemistry is one level, meaning and purpose another.

For Reflection:

• How would you describe the ways in which people are the same as, and different from, other living things? to objects?
• Although we can easily look up the chemical composition of humans in a textbook, we might be a bit more challenged when it came to issues of meaning and significance. What would you say gives significance to your life?