# Biology (life science) explained

Every living being has a few universal characteristics:

- Sustained by consuming a substance that is then metabolized into energy (that energy measured in calories).
- Consumes some type of gas that transfers carbon into or out of the organism.
- A means to make some form of [decision](people-decisions.md), even if it's a rudimentary impulse.
- Some form of "skin" that establishes a clear [boundary](people-boundaries.md) against the surrounding environment.

In many ways, the structures that form life are akin to remarkably well-designed [technology](technology.md), with many built-in redundancies and fail-safes.

Obvious questions that remain unanswered:

- How did life begin?