Here is the order I do buy the Tech’s

1. Harvesting Level 2
2. Science Level 2
3. Medicine Level 2
4. Harvesting Level 3
5. Science Level 3
6. Medicine Level 3

The reasoning is first you need a reliable food source, and although the crops come and go, I can easily keep 1200 in the food bin. Medicine level 2 is important if you want the villagers to live past 60 or so, which I believe is important in the early stage of the game. After the six above, I will go with building level 2 and 3. I will through Spiritually level 2 in once I have a dead villager and will leave it bee until I need to go to level 3 at the end of the game.

This of course is just one way to play, and I am flexible after #3 above.

Hope this helps.

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The VI