The selection pressure isn't coming from whether or not to reproduce *at all*, since that's a given. It's about *how quickly* to reproduce.
From an evolutionary perspective, the correct time to give birth is "as soon as you've arranged enough [resources etc] that your offspring will survive to have kids of their own". Delaying longer than that causes your own lineage's exponential curve to lag behind other lineages' exponential curves, so that at any given time you have fewer descendants than they do.
no subject
The selection pressure isn't coming from whether or not to reproduce *at all*, since that's a given. It's about *how quickly* to reproduce.
From an evolutionary perspective, the correct time to give birth is "as soon as you've arranged enough [resources etc] that your offspring will survive to have kids of their own". Delaying longer than that causes your own lineage's exponential curve to lag behind other lineages' exponential curves, so that at any given time you have fewer descendants than they do.