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| Aflevering | Eerste uitzending |
|---|---|
| S04E01 - Hitler's Secret Weapon | 05/01/1977 |
| S04E02 - The Hot-Blooded Dinosaurs | 12/01/1977 |
| S04E03 - What Price Coal? | 19/01/1977 |
| S04E04 - The Sunspot Mystery | 02/02/1977 |
| S04E05 - The Plastic Prison | 09/02/1977 |
| S04E06 - Incident at Brown's Ferry | 23/02/1977 |
| S04E07 - Bye Bye Blackbird | 02/03/1977 |
| S04E08 - The Pill for the People | 09/03/1977 |
| S04E09 - The Gene Engineers | 16/03/1977 |
| S04E10 - Sociobiology : The Human Animal | 23/03/1977 |
| S04E11 - The Wolf Equation | 30/03/1977 |
| S04E12 - The Dawn of the Solar Age | 20/04/1977 |
| S04E13 - The Business of Extinction | 20/04/1977 |
| S04E14 - The Red Planet | 27/04/1977 |
| S04E15 - The Tongues of Men : Disaster at Babel (1) | 11/05/1977 |
| S04E16 - The Tongues of Men : A World Language? (2) | 18/05/1977 |
| S04E17 - Linus Pauling: Crusading Scientist | 01/06/1977 |
| S04E18 - Across the Silent Barrier | 22/06/1977 |
| S04E19 - The New Healers | 29/06/1977 |