Does the hormone system contain an ability to plan for the future?
To what degree are animals machines that respond mechanistically to inputs, and to what degree are they agents working for their future self-interest?
Camilla Håkonsrud Jensen and Jacqueline Weidner.
In the paper Hormonal adjustments to future expectations impact growth and survival in juvenile fish which appeared in the recent PhD theses of Camilla Håkonsrud Jensen and Jacqueline Weidner, we asked how the hormone system of a juvenile fish is regulated, with regard to feeding, growth and survival.
We found, as one might expect, that hormone levels are partly explained bottom-up as a response in the organism to the current and near-past conditions of the fish and its environment, and partly as a an instrument for top-down evolutionary adaptation control to maximize fitness.
But we also found that for these modelled fish that lived in a simulated environment with fluctuating food resources, it would be optimal if the hormone system could anticipate likely environmental change and prepare the fish for this before it happened. Is this possible?
In our model, the hormone system evolved a capacity for preparation for the expected near future, by inferring from the difference between the long-term average state of the environment and its current state. However, this was in a model. What about natural fish, someone?
Hormonal adjustments to future expectations impact growth and survival in juvenile fish. Oikos. doi.org/10.1111/oik.07483
Camilla Håkonsrud Jensen, Jacqueline Weidner, Jarl Giske, Sergey Budaev, Christian Jørgensen & Sigrunn Eliassen 2020.