Both Sides, Now
“Humans tend to fish down the food chain (and that the top of the food chain is made up disproportionately of large species) and that they tend to hunt large individuals within species suggest that the pattern of threat to larger species reflects human activity, especially hunting and fishing,” states Payne.
In fact, all previous mass extinctions had a greater impact on smaller sea animals or were non-selective when it came to body size – marine species were threatened equally, irrespective of how big they were. There was something strange about the current extinction, something never before seen in science, and the authors of the study attempted to predict the consequences.
“It is difficult to predict the specific responses of other species to the removal of large species because ecosystems have complex sets of interactions,” Payne told UW360. “In many ecosystems, the effects of removing large species cascade through the ecosystem, affecting many other species in unpredictable ways. This is one of the key challenges for conservation biology – it is often difficult to know what will happen when species are removed from ecosystems or driven entirely extinct.”
The Big Five Mass Extinctions
65 million years ago: Cretaceous-Tertiary mass extinction sees 76% of all species lost
200 million years ago: End Triassic mass extinction sees 80% of all species lost
248 million years ago: Permian mass extinction, nicknamed “The Great Dying”, sees a staggering 96% of all species lost
359 million years ago: Late Devonian mass extinction sees 75% of all species lost
443 million years ago: Ordovician-Silurian mass extinction sees 86% of all species lost
A mass extinction is a relatively sudden, global decrease in the diversity of life forms and almost completely restarts the planet’s ecology.
Past studies have looked deeply into how such extinction events have taken place. Research has previously hinted at how mass extinctions have surprisingly occurred regularly over the long haul – in the last 250 million years, there’s been a large “die-off” almost every 26 million years. Some scientists go on to suggest that these extinctions might sometimes be driven not by, say, climate change or impacts from space (huge asteroids), but the emergence of “super predators”.
Live Science reported how in 2005, a scientist developed a computer simulation representing a population of many species competing for food and living space. Much of the time, “medium efficiency” predators prowled the virtual world and their numbers fluctuated only slightly in response to changes in prey population size.
But every so often, mutations would lead to the evolution of a super predator that quickly devoured an entire prey population, which in turn led to its own extinction. The critters that survived the “predatory apocalypse” gradually mutated to fill new ecological niches, and the cycle began anew. There are parallels with this situation and the situation today: With the increasing human hunting pressure of intense whaling and overfishing of marine life, humans could be considered super predators of this epoch.
Down to You
“Human activities appear to play a large role in the sixth mass extinction,” says Payne. However, he remains positive about how we can control our own actions: “The good news is that this means changing human activities can play a major role in averting a mass extinction. The outcome is in our hands.”
ions. Payne suggests “the big question is whether we can change our practices such that we save most or all of the species that are currently threatened. If we do not and we end up losing all of the currently threatened species to extinction, then we will approach the magnitudes of the previous mass extinction events.”