The tremendous timespans involved in biological evolution offer a new perspective on the question 'why is our Universe so big?' The emergence of human life here on Earth has taken 4.5 billion years. Even before our Sun and its planets could form, earlier stars must have transmuted pristine hydrogen into carbon, oxygen and the other atoms of the periodic table. This has taken about ten billion years. The size of the observable Universe is, roughly, the distance travelled by light since the Big Bang, and so the present visible Universe must be around ten billion light-years across.
The galaxy pair NGC 6872 and IC 4970 indicate the vastness of the Universe. Light from the bright foreground star has taken a few centuries to reach us; the light from the galaxies has been travelling for 300 million years. The Universe must be this big - as measured by the cosmic number N - to give intelligent life time to evolve. In addition, the cosmic numbers omega and Q must have just the right values for galaxies to form at all.
This is a startling conclusion. The very hugeness of our Universe, which seems at first to signify how unimportant we are in the cosmic scheme, is actually entailed by our existence! This is not to say that there couldn't have been a smaller universe, only that we could not have existed in it. The expanse of cosmic space is not an extravagant superiority; it's a consequence of the prolonged chain of events, extending back before our Solar System formed, that preceded our arrival on the scene.