Halliday & Matthiessen (1999: 609):
… we want to emphasise the evolutionary perspective, since this allows us to start from what human beings have in common with other species rather than always insisting on our own uniqueness: when we talk of “construction of reality” it is almost impossible to avoid taking our own construction as the norm, whereas parakeets, pythons, and porpoises have very different experiences to construe — different both from each other’s and from those of people.