Sixteen windows into one human being
16×1 does not claim that the human body has sixteen systems.
Human biology is much more complex than that.
There are classical organ systems, regulatory networks, structural matrices, biological ecosystems, signalling pathways and cross-system relationships.

Some biological networks operate across several conventional systems at once.
The endocrine network is one example.
The autonomic nervous system is another.
The microbiome, lymphatic network, circadian system, connective-tissue matrix and immune network also cross conventional anatomical boundaries.

That is why 16×1 uses the term:
BIOLOGICAL AGE DOMAINS
A domain is a meaningful window into one dimension of your ageing biology.
Each domain can contain several systems and subsystems.
And each can influence the others.
The purpose is not to divide the human being into isolated pieces.
It is to make complexity visible.
The map separates the domains so that we can understand the whole.

The final Age Map brings those domains back together and asks:

• Which are strongest?

• Which are under the greatest pressure?

• Which appear older?

• Which appear younger?

• Where is compensation occurring?

• Which domain may have the greatest leverage over the rest?