Search any living room or board game cafe and you are likely to find a Jenga tower lying somewhere on the shelves. The game is so ubiquitously known that nearly everyone has their own horror story of testing their luck with one block, only to find it catch onto another and send the entire tower toppling.
Instead of creating towers on our coffee tables, humans have started playing a much larger, higher-stakes game of Jenga in the past few hundred years – and we’re about to find out if our tower is going to fall.
In an ecological community, all species play a certain role to help the community function and remain resistant to changes (that can be referred to as ‘community stability’). However, to quote George Orwell, “all animals are equal, but some animals are more equal than others”.
These special species serve particularly important roles (e.g. soil churning, predation that keeps prey in check) that affect a large number of other species. Because of the key role they play, these aptly named “keystone species” are integral for maintaining community stability and resilience.
Counterintuitively, a keystone species’ effects usually far outweigh their abundance, and when compared to their non-keystone counterparts, their numbers are actually quite small. We can think of these keystone species as a load-bearing block in the center of a large and complex Jenga tower that is an ecosystem. The entire integrity of the tower – and the ecosystem – rests on the weight of that single, small block.
But what does this have to do with humans?
In 2016, Boris Worm and the late Robert Paine (a pioneer of the keystone species concept) proposed that humans likely act as a “hyperkeystone species”. They hypothesize that through our intensive exploitation of wildlife (e.g. hunting, fishing) and more subtle, non-exploitative effects on wildlife (e.g. climate change, ocean acidification), we disproportionally affect keystone species. In negatively affecting keystones, we can indirectly cause large and damaging ripples throughout ecological communities. As keystones already exist in relatively smaller abundances, these disturbances are more likely to push keystones towards low levels compared with other, more abundant, species.
The implications of this hypothesis are pronounced. They suggest not only that human disturbance spreads far beyond one target species, but also imply that the scope and magnitude of human disturbance is far greater than previously thought. We are targeting our load bearing Jenga blocks, and if we don’t fully acknowledge and address the possibility of our hyperkeystone impacts, our towers will soon come falling down.
Our current research examines this Hyperkeystone hypothesis, as well as the potential impacts that humans as a hyperkeystones have on communities. That process starts with creating a list of keystone species – something which has surprisingly not been done before. Only after that can we measure different systems’ community responses with and without their respective keystones. By tackling this problem comprehensively, we can identify keystone populations that are rapidly changing, or that are the most vulnerable. While we might not be able to put back the Jenga blocks we already removed, we can certainly make smarter decisions about which blocks must stay, leaving our Jenga tower standing for generations to come.