Ever since his best-selling novel "The Da Vinci Code" first hit shelves in 2003, author Dan Brown has entertained readers with adventures filled with conspiracy theories, riddles, symbols, and dramatic twists and turns. In the middle of each stands Robert Langdon, a fictional Harvard professor of symbology who often solves the puzzles, beats the bad guy and saves the world.

Dan Brown's book Langdon's latest globetrotting adventure plays out in theaters this weekend in "Inferno," an adaptation of Brown's best-selling 2013 novel. Directed by Ron Howard, and once again starring Tom Hanks as the clever professor, "Inferno" features Langdon attempting to stop a billionaire geneticist named Bertrand Zobrist from unleashing a virus that will kill billions of people.

While Zobrist may sound like your typical madman, Brown is quick to give some context to his nefarious intentions. His reasons have nothing to do with wiping out humanity, but saving it from itself by reducing global population and ensuring the species' long-term survival. Here's one of Zobrist's statements from the book to give you an example of his doomsday viewpoint:

“Dante’s hell is not fiction ... it's prophecy! Wretched misery. Torturous woe. This is the landscape of tomorrow. Mankind, if unchecked, functions like a plague, a cancer … our numbers intensifying with each successive generation until the earthly comforts that once nourished our virtue and brotherhood dwindled to nothing ... unveiling the monsters within us ... fighting to the death to feed our young.”

So what does that have to do with Malthusian theory?

As readers learn in the novel, Zobrist embraces what's known as Malthusian theory, based on the writings of 18th century economist and demographer Robert Malthus. In his 1798 paper, An Essay on the Principle of Population, Malthus argued that unchecked human population would rise exponentially, doubling every 25 years, while agriculture would increase only arithmetically (rising as 1,2,3,4, etc.). Such a scenario would quickly lead to global famine, starvation and war. Malthus wrote:

"The power of population is so superior to the power of the earth to produce subsistence for man, that premature death must in some shape or other visit the human race. The vices of mankind are active and able ministers of depopulation. They are the precursors in the great army of destruction, and often finish the dreadful work themselves. But should they fail in this war of extermination, sickly seasons, epidemics, pestilence, and plague advance in terrific array, and sweep off their thousands and tens of thousands."

So yes, this guy was clearly the life of the party. But was he wrong? Malthus believed that 1 billion people would be the tipping point, but we crossed that line in 1804. Today, we number nearly 7.4 billion and counting. Considering it took all of human history to reach 1 billion –– and just a little over 200 years to match it seven times over is alarming. What Malthus didn't count on, however, was the scientific and technological progress that would get us here –– with advances in agriculture from industrialization to high-yield, disease-resistant crops making today's population possible. Starvation is a major issue, with some 795 million people without enough food to lead a healthy lifestyle, but the mass apocalyptic starvation envisioned by Malthus has yet to play out.

Population Growth According to the most recent United Nations estimates, the human population is expected to reach 11.2 billion by 2100. (Photo: WorldOMeters)

Of course, we're still growing –– and fast. The current average is roughly 80 million new people every year. According to the most recent United Nations estimates released in 2015, humans are expected to number 9.7 billion by 2050 and roughly 11.2 billion by 2100. The good news is that global fertility rates, thanks to education and improved healthcare, are actually slowing human population growth. Even in Africa, where fertility levels remain the highest in the world, the long-term trend is projected downward.

Problem solved! But wait ...

While our planet may not yet have reached a Malthusian catastrophe, it's increasingly clear that more people in the coming decades will further degrade what precious little harmony we still enjoy with nature. The apocalyptic specter of our demise — whether through war, disease or famine — will likely come from humanity's overconsumption of natural resources.

"Rising consumption today far outstrips the rising headcount as a threat to the planet," Fred Pearce, a specialist in global population, wrote in Prospect Magazine. "And most of the extra consumption has been in rich countries that have long since given up adding substantial numbers to their population, while most of the remaining population growth is in countries with a very small impact on the planet. By almost any measure you choose, a small proportion of the world’s people take the majority of the world’s resources and produce the majority of its pollution."

Our insatiable thirst for resources and over-exploitation of biodiversity is degrading the planet at an exceptional pace. According to the Global Footprint Network, humanity "uses the equivalent of 1.6 planets to provide the resources we use and absorb our waste. This means it now takes the Earth one year and six months to regenerate what we use in a year."

What's necessary to strike balance in the world isn't some madman with a devastating virus, but a serious discussion of population growth, overconsumption and investments in renewables, recycling, education, and contraceptions to counter them. While Malthus's grim predictions have not yet come to fruition, deferred by advancements in science and technology, it's naive to believe that we can continue shoehorning people onto the planet without eventually reaching a cataclysmic tipping point.

Perhaps the real question we should be asking ourselves is not if Malthus was wrong, but when exactly he'll be proven right.

Michael d'Estries ( @michaeldestries ) covers science, technology, art, and the beautiful, unusual corners of our incredible world.

'Inferno' fueled by apocalyptic Malthusian theory
New film, based on the best-selling book by Dan Brown, warns of humanity's demise from unchecked population growth.