| 1 | Sheldon | Glashow | American physicist who won a Nobel Prize in physics in 1950. |
| | Paul | Cohen | American mathematician who won the Fields Medal in 1966. |
| | Carl | Sagan | An American astronomer. |
| | Mr. | Spock | A fictional character in Star Trek. |
| | Hope | Jahren | Protagonist, narrator, and author. |
| | | | The Jahren Laboratory - Hope's Laboratory. |
| | Bill | | Hope's lab partner. |
| 4 | Pharm.D | | Hope's supervisor. |
| | Lydia | | Hope's trainer. |
| | Sydney | Ringer | A British physiologist. |
| | Claude | | The lifer at the prison. |
| | Mr. | Knauer | A meat seller. |
| | | | ECT - Electroconvulsive Therapy. |
| 6 | Jean | Genet | A french novelist. |
| 8 | Buck | | Hope's only friend in Logan County. |
| | | | Part Two - Woods and Knots |
| 2 | Reba | | Hope's chespeake bay retriever. |
| | Professor | Santa | The Elf's Boss. |
| 4 | Stuckie | | Fossilized dog displayed in the museum Southern Forest World. |
| | King | | The huge gorilla. |
| 5 | | | NSF - National Science Foundation. |
| 6 | | | Kudzu - A vine from the Phillipines. |
| 7 | Jackie | | A geriatric mare. |
| | Karen | | The undergraduate lab assistant of Bill and Karen. |
| 10 | Teri | | Hope's graduate student. |
| | Noah | | Hope's genius undergraduate assitant. |
| | Cal | | A teacher / Hope's friend. |
| | Linda | | Cal's wife / Hope's friend. |
| | Olivia | | Cal and Linda's daughter. |
| | | | Part Three - Flowers and Fruits |
| 2 | Ed | | Hope's favorite academic uncle. |
| | Henrik | | A genius guy who formerly works for Ed. |
| 6 | Clint | | Hope's husband. |
| | Sugar | | Hope's brown mare. |
| | Walter | | The head of a department at John Hopkins. |
| 10 | Billy | | Lorna's co-proprietor. |
| | | | Phoenix - A B-and-B Organic Farm. |
| | Josh | | Bill and Hope's newbie. |
| 12 | Coco | | Hope's dog / Reba's successor. |
| | Marge | Piercy | An American Poet. |
| 14 | Matt | | The Experiment leader of Hope's student. |
