Humans could become extinct, a new study concludes, but no single event, aside from complete destruction of the globe, could do us in, and all extinction scenarios would have to involve some kind of intent, either malicious or not, by people in power.
The determinations suggest that the human race itself will ultimately determine its fate.
"I think the ability to adapt very quickly is singular to humanity," project leader Tobin Lopes told Discovery News. "Species progress and evolve to enhance their chances, but it's done over a very long period of time."
"Instinct guides a lot of what we do early in our lives, but the capacity to learn different behaviors as a result of different environments makes humanity capable of survival," added Lopes, who is associate director of global energy management programs at the University of Colorado Denver.
For the study, accepted for publication in the journal Futures, Lopes and his team used a standardized approach for scenario planning called "intuitive logics," which is normally applied to predict business, economic and certain other outcomes.
"The intuitive logics approach, and scenario planning as a practice, starts with the present and works forward to an unknown future," he explained. Co-authors served as "stakeholders," just as they would in planning a business, and identified key concerns that may adversely affect them.
The concerns were ranked according to possible impact and uncertainty before being plugged into the model, which also incorporated known outcomes, such as attack response times, prior pandemic death percentages, and detection-to-cure time frames.
The result was three scenarios in which humans could go extinct. Each consists of multiple events, such as pandemic, warfare, global warming-related occurrences and a meteor strike, which occur in relative succession and result in equally destructive domino effects, such as societal breakdowns leading to economic decline and escalated terrorism.
While any number and combination of doom-and-gloom happenings could destroy the human race, the researchers outlined four, more general types of events that may also serve as "signposts," or events that may signal the unfolding of a defined scenario. In this case, that defined scenario is human extinction.
"The types were non-war human-caused -- whether accidental or intended or purposeful, natural-viral, natural-environmental, and finally nuclear or near nuclear war/engagement between any two nations," Lopes said.
Should a launch of nuclear weapons, an outbreak of disease, an unforeseen side effect of technical and medical advancements, or unusual environmental changes occur, the researchers believe "serious consideration throughout the globe" is warranted.
Side effects of technology and environmental changes "are slow to present themselves, and that's what makes those signposts the most dangerous, in my opinion," Lopes said. "Unfortunately, as we've seen with the impassioned discussion regarding global warming, not everyone can agree on what it is they are seeing or what the data reveal, and that's where a great deal of danger lies."
In yet another paper, accepted for publication in the journal Medical Hypotheses, researcher Sergio Dani of Brazil's Medawar Institute for Medical and Environmental Research, explored the fate of human societies. A prior theory, formulated by UCLA's Jared Diamond, hypothesized that guns, germs and steel strongly affect our outcome.
Dani instead proposed that "gold, coal and oil account for not only the fate of human societies but also for the fate of mankind through the bodily accumulation of anthropogenic arsenic, an invisible weapon of mass extinction and evolutionary change."
Dani explained that exploitation of the named resources is causing rises of arsenic concentrations in the biosphere and "humans are among the least arsenic-resistant organisms."
Nevertheless, "the human race is unlikely to become extinct without a combination of difficult, severe and catastrophic events," Lopes and his team concluded, adding that they "were very surprised about how difficult it was to come up with plausible scenarios in which the entire human race would become extinct."