Heritability, Reflex & Instinct

Question 1

What is/are the condition/s under which evolution can affect a physical or behavioural feature?

Answer 1

The feature needs to be variable, and heritable, and there needs to be selection pressure for or against the feature.

Question 2

What are some common physical signs of the Fight or Flight responses?

Answer 2

Hand shaking, sweating, dry mouth, increased heart rate, tunnel vision.