Prime Timeline
   | Year | Event | 
   | 1966 | 
         ● [1]
         The population of Miri's planet begin a project aimed at greatly slowing the ageing process. Although the project is successful for children, it wipes out the entire adult population of the planet. [1]
      
 | 
   | 2266 | 
         ● [2]
         The Enterprise visits Miri's planet, a world which turns out to be an eerily close parallel of Earth. It is discovered that most of the population has been destroyed by a biological catastrophe caused by a projected intended to extend life. The few remaining natives set about rebuilding their civilisation with Federation help. [2]
 | 
   
Colour key
● - Shows the canon status and reference of the year for this event
References
| # | Series | Season | Source | Comment | 
| 1 | TOS | 1 | Miri | Spock says that the project was begun 300 years ago | 
| 2 | TOS | 1 | Miri |  |