Approach Anxiety: What Is It?
*ESS: An evolutionary stable strategy describes tactics employed by individual organisms when competing with one another for a given resource. These tactics can be behavioural or structural, and the organism does not consciously choose them, but adopts them as a natural consequence of evolution. Both structures and behaviours are heritable (capable of being inherited), and as some are successful and some fail, only the better ones are passed on.
And so when we say conservative ESS prevailed, it means that on a group level, caution was generally favoured over impulse or blind courage. It can be hypothesized that we evolved such that group stability was ensured by a cautious majority and a risk-inclined minority.