This is of course shown by the whole existence of the telepaths and the way that they represent an undeniable proof of the way in which humanity itself is evolving and moving on from its original form into something new and different. The Waknukians, defined, of course, by the stern and unyielding figure of David's father, are desperately trying to stamp out any example of what they see to be deviations of the "true form," which is defined on their own human form. Therefore, when they discover the existence of a different kind of human that is able to communicate telepathically, they do everything they can to stamp it out and to prevent it from being a threat to them.
The most incisive criticisms of their position come of course from the Sealander woman, who is able to look at the Waknukians with a more experienced eye than the telepats. Note her assessment of them and of the futility of trying to stop inevitable change:
The static, the enemy of change, is the enemy of life, and therefore our implacable enemy... I know little about your lives, but the pattern scarcely varies wherever a pocket of the older species is trying to preserve itself. And consider, too, what they intended to do to you, and why...
The fate of the Waknukians will be their own death, as struggling to resist this "superior variant" from overtaking them will only ensure their own extinction. Trying to freeze the development of man in one form is therefore an ultimately futile ambition, because the evolutionary forces will not be so easily thwarted.