It is knowledge that has to be taught.

Marie Dorion had this knowledge.

She had grown up in a world where it was practical and necessary.

What she lacked, that the standard fur-trade expedition would have provided, was backup.

She had no other adults.

She had no shared labor pool for the work of survival: gathering food, building shelter, managing the children, scouting the terrain.

She was doing everything alone, with two small children who needed care and warmth and food and cannot have been entirely passive bystanders in the process.

The physical demands were extraordinary.