Man's place among the diving mammals

A theory was forwarded in 1960 that humans significantly deviate in anatomy, physiology and behavior from their closest relatives, the great apes, and instead resemble diving mammals, as a result of a period of selective pressure to enter the water (Hardy, 1960). Humans can learn how to dive and in many aspects resemble diving mammals, but how similar is man when compared with aquatic species? To evaluate this, we compared diving performances in a number of aquatic, semiaquatic, and terrestrial species. As an index of aquatic diving specialization, we used maximal and average dive depth and duration, and proportion of time spent under water during repeated dives. Our analysis indicates that aquatic "deep divers" form a separate group, to which humans -And most aquatic and semi aquatic mammals - do not compare in diving specialization. Several species perform dives of intermediate duration and to intermediate depths, and form a group of "moderate divers". A great number of species show more modest diving skills, despite being dependent on an aquatic life or food sources, and form a group of "shallow divers". Humans fit well in this latter group and their maximum diving capacity is well within the typical ability performed by shallow near shore foragers. It may be the case that, as most accessible food is present near the shores, a great number of air breathing species have specialized to utilize this niche, while only a smaller group have developed the specialized extreme physiology necessary for extended deep diving. While foraging in shallow water, humans may repeatedly dive to 20 m and spend as much as 60% of the time submerged in shallow diving, and trained individuals have reached depths of 100 m on single maximal dives. From this perspective, human diving capacity is well within that of typical diving mammals.

Duke Scholars

Author Andreas Fahlman Marine Science and Conservation