“The genetic code does not, and cannot, specify the nature and position of every capillary in the body or every neuron in the brain. What it can do is describe the underlying fractal pattern which creates them.”
— Academician Prokhor Zakharov, “Nonlinear Genetics”
Gene Splicing is a third-tier economic technology that requires Biogenetics and Ethical Calculus, which is an interesting mix of prerequisites. In the game, it allows the creation of the Research Hospital base facility, which as you might expect provides both research and psych energy multipliers. But that’s small potatoes compared to the other effect: it lifts the early-game nutrient restrictions on tile yields by enabling agronomists to tailor core staple Earth plants to the alien environment.
It requires a little discussion of game mechanics to understand why this is such a pivotal technology. At the beginning of the game, a tile can only yield a maximum of two of any of the three base resources (nutrients, minerals, or energy). This is an especially sharp limit for nutrients, because each citizen requires two nutrients to support itself. This means that, at best, a worker can only break even working farms. In the early game, bases tend to be small and few citizens can afford to work as specialists of any kind.
There are only two exceptions to this rule before the restriction is lifted. First, the restrictions do not apply to the tiles that bases are planted on. Additionally, no population point is required to work to get this yield. This is balanced by the fact that the underlying terrain for a base is overridden, replacing the base tile with a 2-1-1 yield. With Recycling Tanks, this increases to 3-2-2, meaning that the base tile can support 1.5 citizens doing something that doesn’t bring food into the base. It doesn’t matter if your base is in the lush terrain or in the middle of the desert; it always yields basically the same decent yield.
Second, any tile that contains a special bonus has that restriction lifted on that tile only. So that means that if the player happens to find a nutrient bonus and build a base next to it, one worker can yield three, four, or even five nutrients, depending on the moisture of the underlying terrain and any improvements built on the tile. This is huge. And it goes double for a nutrient bonus, since now it’s possible for a worker to do more than break even, enabling other workers to act as specialists or work arid mines or solar collectors.
This technology enables farms in lush terrain (whether natural or artificially created with condensors) to routinely yield three or four nutrients. Basically, the faction can get something resembling the benefit of nutrient bonuses everywhere if they also have the Weather Paradigm. If not, they can still regularly exceed the cap on the ocean (with three nutrient kelp farms) or with farms on rainy terrain.
This is why experienced players generally place the transition from the early game to the mid-game somewhere around the lifting of these resource caps. And if we imagine the experience of the colonists from the perspective of this model, it is these technologies that enable the shift away from the painfully hard experience of the first generation of colonists to the explosive growth experienced by their children: the first generation of humans to grow up knowing only the domes, the fungus, and the alien sky.