For thousands of years, and in large part due to our development of advanced tools and technology, humans have stood at the top of nature’s food chain. There are virtually no (non-human) animals left on this planet that can pose a threat to the continued existence of humanity.
Yet as a new study from a team of researchers at the University of Victoria, University of British Columbia, University of Northern British Columbia, and Dalhousie University suggests, the unrivalled ecological dominance of humans has created some devastating effects for other wildlife on our planet.
For years now, we have known that humans greatly impact global wildlife. From the introduction of microplastics into the food chain, to the wiping out of over 80% of wild mammals since the beginning of human civilization — despite us constituting only 0.01% of life on Earth — it would be an understatement to say humans have made their presence known in nearly every corner of the Earth.
Modern Humanity and Its Consequences
The new study, published in Nature’s Communications Biology, investigated the ecological impact of predatory human behaviour on vertebrate species. As the authors outline, the development of human hunting, fishing, and trading technology has radically transformed the position of, and relationship between, humans and other vertebrate species.
The three main outcomes investigated by the researchers were: 1) how human behaviour impacts vertebrate prey species, 2) how human predatory behaviour compares to other similar predator species, and 3) how ecological diversity will be impacted by the loss of certain species that are overexploited by humans.
To gain greater insight into such a complex network of interactions, the research team used “use and trade” data from the International Union for the Conservation of Nature, which classifies the reasons why 46,755 vertebrate species are killed or captured by humans. These reasons could include for food, sport hunting, animal feed, or pets, among others.
Patterns of Human Predation
The researchers found that humans use nearly a third of all vertebrate species found on Earth — whether that be through killing or capturing. Of the nearly 15,000 species used, over half (55%) are killed for food, though patterns differ between marine and terrestrial vertebrates. For example, over 70% of used fish are hunted for food use, while over 70% of used terrestrial vertebrates are used as pets (with 39% being used as food). Nearly a quarter of species are used for multiple purposes.
When the researchers looked at the species that were used, they found that they were more likely to have larger bodies, live longer, and be herbivores compared to the species that weren’t used. When compared to other natural predators, such as owls, lions, and orcas, the researchers found that the predatory role of humans is up to 1,300 times larger. In other words, our predatory niche — or the ecological position and patterns of our use of other vertebrates — is exponentially broader and more varied than nearly all other predators on Earth.
In regards to extinction, human use of the 15,000 used species can be considered a threat for nearly 40% of vertebrates. This may be the most startling finding in the paper, as it supports previous findings that current human consumption patterns may be unsustainable for long-term non-human wildlife.
As the authors warn, “without changes to predatory behavior by humans, these losses are likely to further reduce the ecological diversity present among the world’s vertebrates […] with consequences for global ecosystem functioning.”