Sentence:  The whales, porpoises and seals have however a reason that man does not possess for being <WSD>anosmic</WSD>. For they, in common with all the living world of earth and air, left the sea millions of years ago and, as they developed lungs with which to breathe, so did they modify their organs of smell to receive sensations from air, not water. Eons later, in comparatively recent geologic times, when these few mammals left the land and returned to the water, this differentiation for air-smelling had gone too far. Their senses of smell failed to react to water-borne stimuli. ... It is worth discussing these <WSD>anosmic</WSD> animals, and what caused them to lose the sense of smell. 
Meaning of the word marked with <WSD> tags:  Lacking olfactory organs; anosmatic.