1) Open /files/scripts/effects.gd
2) Go to the bottom (not sure if my file has different line number)
3) Find the following:
func animalistic1(person):
person.energy = 8
func animalistic2(person):
person.energy = 16
func animalistic3(person):
person.energy = 25
4) Replace those lines with the following (Don't change formatting - just add the "+" in the right place):
func animalistic1(person): person.energy += 8
func animalistic2(person): person.energy += 16
func animalistic3(person): person.energy += 25
5) ...
6) Profit