Marine defaunation and the colonization of the Oceans

The rise of human civilization from primitive hunter-gatherers occured in parallel with another event on land . The mass extinction of a wide variety of large animals such as the mammoth was also happening around the same time. Several scientists believe that there was more to simple hunting and habitat modification by man that caused this, citing also non anthropogenic climate change and that some form of disease wiped these out. This latter point about disease is an interesting one as livestock of early man may have also acted as vectors of this. The possibility that some or all of these factors worked in combination of some form should not be discredited off course.  When the large animals died through this event known as the pleistocene overkill, humans turned to smaller animals , other forms of food like plants and through this need agriculture is thought to have evolved. 

According to new research published in the Scientific Journal Science the exact same pattern has been happening in the Oceans of the world but with a significant delay. Thus as the terrestrial resources dwindled humans have turned and are expected to do so a lot more in the future turn to the oceans . It also shows how after all these millenia we are still very much depended on wild animal protein to survive primarilly of large mammals and that we turn to smaller ones once these run out.

This off course does not mean defaunation only but other issues related to human impact increasing such as mining and habitat modification.The infographic bellow from the rellevant publication shows the pattern of human colonization on land rellative to what has happened so far and is expected to happen in the future.

It is important to note that the ecological equivelant of agriculture on land is aquaculture

As scientists point out in this research it is still not too late to stop this situation for the sea and since only very few large marine mammal species have gone extinct so far and there is plenty of opportunity for restoring marine ecosystems provided we act soon.

(McCauley et al., Science 2015)