The complex continent conundrum

There are seven continents on Earth, or so we learned in school. But it turns out that these designations are not as straightforward as they seem, and different scientists have different views on how continents should be grouped based on geographical and social conditions.

How many continents are there?

The seven continents are Africa, Antarctica , Asia, Europe, North America, Oceania and South America — but some experts argue that there could be less. "There is a question as to what exactly defines each continent, which has caused confusion among geography teachers and students across the globe," said BBC Science Focus . "The lack of a definitive answer as to what exactly makes a continent has led to the four, five, six and seven-continent responses around the world."

While the U.S. teaches that there are seven continents, Europe teaches that there are only six, with North and South America counting as one consolidated America. Some combine Europe and Asia into Eurasia, since the two are connected by land. Another model denotes Africa, Europe and Asia as one continent, Afro-Eurasia, because the "landmass is completely traversable by land and not broken up by any water (except the Suez Canal in Egypt, which was built by humans in the 19th century)," said IFL Science .

"A continent is typically defined as being a large continuous mass of land, loosely correlating with the positions of the tectonic plates and 'floating' on Earth's continental crust," said Science Focus. With this definition in mind, one study recently published in the journal Gondwana Research argued — controversially — that North America and Europe are actually one continent, which makes six continents total. That's because "North America and Eurasian tectonic plates have not yet actually broken apart, as is traditionally thought to have happened 52 million years ago," said Jordan Phethean, the lead author of the study, to Earth.com . The evidence comes down to Iceland and the Greenland-Iceland-Faroe Ridge, which according to recent findings "contains geological fragments from both European and North American tectonic plates," said Earth.com. "This discovery suggests that these regions are not merely isolated landforms; they are interconnected components of a larger continental structure."

What makes a continent?

Continents are difficult to define because the Earth is often changing. Originally, about 300-200 million years ago, Earth contained one landmass known as Pangea, a supercontinent that eventually broke apart into separate masses.

"Plate tectonics and the Pangea supercontinent suggest that continents move and break up over (extremely long) periods of time due to convection from the decay of radioactive elements in the mantle," said Science Focus. The current continents are also not the ones that always existed. For example, scientists recently mapped the completely submerged microcontinent of Zealandia , which is believed to have broken off from Antarctica about 100 million years ago, and then from Australia about 80 million years ago.

While land masses and tectonic plates are a main consideration in determining continents, they are not the only one. Societal views may also play a role. "To imagine Europe and Asia as constituting equivalent 'continents' has long been recognized as the ethnocentric cornerstone of a Western, or Euro-American, world view," Chris Hann, the founding director of the Max Planck Institute for Social Anthropology, said in a 2016 paper . "The amalgam Eurasia corrects this bias by highlighting the intensifying interconnectedness of the entire landmass in recent millennia."

In general, "even the most scientific of definitions has some degree of subjectivity," said IFL Science. That means "it's extremely hard to divorce the concept of a continent from the sociocultural forces that shape our perception of Earth and our place within it." As Dan Montello, a geography professor at the University of California, Santa Barbara, said to HowStuffWorks : "There simply is no 'czar' or 'CEO' of continents or any other ultimate authority, so it is pretentious for anyone to claim they have the authoritative answer."