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Brian Lehrer: Brian Lehrer on WNYC. Now, we will revisit one of the questions from the science topics Pledge Drive Quiz we did back on May 17th. We had asked a question about how many continents there were, and we figured that was a low-hanging fruit kind of question, but it may have been more complicated than the answer we gave. We're following up thorough and accurate, we hope and also because this is really interesting. The question was this, true or false, there are eight continents on earth. The answer that we had as the correct answer was true.

The "seven" obvious continents that most people grew up learning about Asia, Africa, North and South America, Australia or Oceana, Antarctica, and Europe, plus something called, more recently discovered, Zealandia, number eight. That was documented just last year as a new "continent." We framed it as a science question, but after a lot of back and forth about it, it looks like we were actually wrong, or at least wrong to frame such a simple question about what turns out to be a complicated topic.

Complicated, because those seven obvious continents are really only obvious to those who learn geography here in the United States. In other places in the world, they treat North and South America as one continent because they're one landmass. The human made Panama Canal notwithstanding, and some places in the world treat Europe and Asia as one continent also because it's one landmass. In reality, there's no scientific consensus on what makes a continent because the question is as much about human culture as it is about geology or geography.

Joining me now to tell us everything they didn't teach us in elementary school when they taught us the continents, please welcome Martin Lewis, professor emeritus from Stanford University, his 2010 article on this is fittingly called, How Many Continents Are There? Professor, thanks for joining us. Welcome to WNYC.

Martin Lewis: Well, thank you very much for having me.

Brian Lehrer: I guess the obvious first question is, what's a continent?

Martin Lewis: The general definition of a continent is a large body of land, more or less separated from other bodies of land by intervening waterways. The problem is Europe has never matched that definition. There's no real separation between Europe and Asia. It's usually put at the Ural Mountains, but they're not very formable and they end in the steps of Kazakhstan. Europe and Asia was actually the first continental distinction, and it was generated by ancient Greek geographers who had a limited knowledge. As far as their knowledge went, these two bodies of land were almost separated because they had to pass through the Dardanelles, the Bosporus, the Sea of [indecipherable] going up into the Black Sea. It seemed like there were two distinct bodies of land.

Brian Lehrer: What has been the value of, or the impetus for dividing the globe in this particular way, and how has that changed over time?

Martin Lewis: Well, you need systems of global division to think and talk about the world. The continental schemes comes from ancient Greek geography, first Europe and Asia, and then Africa was added and they were the three parts of the world. In the Middle Ages, this was given a theological overview. It reflected the trinity. The world was often depicted as divided along the Black Sea, Red Sea, and Mediterranean Sea with Jerusalem in the center. It was a theological view of the world. When the Americas were discovered, that generated a cosmological crisis and eventually the Americas were added as a fourth part of the world.

The term continent had been used periodically, previously, but it really began to be used at that time. Then eventually, Australia and Antarctica were added as separate continents. There's no real scientific differentiation.

Brian Lehrer: Listeners you can join this conversation if you want. Anybody have a question about continents? I see one text message already from a listener who writes, "Ha. I had to google the continents after you asked that question." I'm glad you're following up because it seems like the answer is between four and eight and nobody really has a definitive answer and no one can agree. Anyone else out there, did you learn the continents differently if you grew up in a different country than the United States than we teach them here. 212-433-WNYC. How do you think it's affected the way you group and categorize and otherwise see the globe? See people on earth for that matter?

Call 212-433-WNYC. If anybody wants to weigh in with a story about your understanding of the continents from wherever you are originally from, or a question, 212-433-9692. What if you are from either North or South America? Of course that would include everybody from the United States, but this idea of one American continent versus two American continents, if you're from North or South America, 212-433-WNYC, or a question about this recently identified eighth continent by the US numbering system, Zealandia. 212-433-9692 for Martin Lewis, professor emeritus at Stanford, who's 2010 article on this was called How Many Continents are There?

Here in the US, Professor, we learn our continents differently than they do in other parts of the world. Can you give us a rundown of how different cultures around the world divide the globe? Is there more to say than the way I laid it out in the intro?

Martin Lewis: Most countries in their educational system basically follow the standard model. Although as you said, in Latin America, generally the Americas are viewed as one continent. You do get a variable system. Sometimes Australia is excluded, considered a large island. It does sit on its own tectonic plate. Geologically speaking, you could call it a continent. Antarctica is often left out as well because of its lack of human habitation. One thing I will say is, there are many, many ways to divide the world.

Africa is not separated from Asia, well, except by the Suez Canal. It's the same thing with the Americas. Some geographers consider Eurasia and Africa to form Afro-Eurasia as a single continent. That was actually joined to North America during glacial periods when the bearing land bridge was opened. Some would say, well, there's really one giant continent, Afro, America, Eurasia, and then Australia is a separate one. You can really see this with wildlife. Temperate species in North America are very similar to those of Europe and Asia, whereas Australia is very different.

Then places like Madagascar can be considered a micro continent, or you can even get smaller little bits of land. Zealandia includes New Zealand and New Caledonia and sits on a submerged piece of continental crust, but sometimes New Caledonia has been considered a nano continent. There are really many, many different ways to view the world.

Brian Lehrer: I did not think that we were going to fill the board all 10 of our lines lighting up instantly on this question about continents but we have. We're going to take a couple of callers, as many as we can get in in our remaining time. Also a lot of text messages. Here's the question I have to answer. Listener writes, "Did you get back in contact with that caller who got the question wrong and give him a hat?" The answer is, "Yes, we did." [laughs] That's a starting point. Jose in Fort Lee, you're on WNYC. Hi, Jose.

Nutley: Hi. Yes, it's actually Nutley, not Fort Lee.

Brian Lehrer: Oh, Nutley. I'm sorry.

Jose: Yes, no worries. Yes, no, what I wanted to share. I'm from Puerto Rico originally, and I went to school in the '80s and '90s there. What I wanted to share is that throughout elementary, middle, and high school, we were actually taught at least three different versions of what the continents were. We were taught the one that is five continents. We were taught the one that is seven continents. We were taught six continents. It all changed depending on who was teaching it.

Brian Lehrer: Did it inform your sense of identity or place in the world in any way, depending on which way you thought of it?

Jose: I think it made it for me as a Puerto Rican and as a person who doesn't call United States, America, I call it United States. It just made it easier for me to identify as American because I always felt and still feel that I'm part of America as in the overall one continent of America, North, South, Central and Caribbean. I think that influenced how I see myself. and that just made it confusing actually.

[laughter]

Brian Lehrer: Jose, thank you very much. Not confusing, but clarifying. Really appreciate it. Call us again. Another listener writes kind of similarly, "I was born in Brazil and always knew myself as an American because of our continent." Here's a text message question, Professor. Listener asks simply, "What is the purpose of having continents or defining continents?"

Martin Lewis: The purpose would be, we just need ways of dividing the world to talk about it intelligently, but there are alternatives. What I use in teaching is known as the world regional system that divides the world somewhat differently. For example, rather than speak of one Africa, we talk about Sub-Saharan Africa, and then we join North Africa with the Middle East because that's a coherent historical and cultural region. Latin America then would be differentiated from North America, or northern North America, if you will, and Asia would be divided into East Asia, Southeast Asia, Central Asia, and so on. Asia, in particular, is just too large really to work as a single division of the world culturally, historically, economically, or in any other sense.

I think what's important is to use multiple systems of division and not just rely on one. In a way commend the teachers of the caller from Puerto Rico. I would also like to add that many people in Latin America find it off-putting, or offensive to refer to citizens of the United States as Americans because, well, they are Americans too in a broader sense, the term US American is sometimes used in those countries.

Brian Lehrer: Another listener asks, "Why isn't Greenland a continent?" I think they're looking at it being physically large sitting up, there separated from everything by water.

Martin Lewis: Yes, that's a great question. The usual reason would be because Greenland sits on the same continental plate as North America. Continental crust is very different from oceanic crust, it's much thicker, it's much lighter weight. The oceans or waters between North America and Greenland are very, very shallow. If you were to drop sea level, and sea level has dropped in different geological eras, then it would be joined together. The same with Australia and New Guinea, they sit on the same continental plate, and the waters between them are very shallow.

Brian Lehrer: Finally, a listener writes, "One continent, that is the earth is all one continent, all the water sits on top of it." We have 15 seconds for the last word.

Martin Lewis: Well, I can say there's a real major difference between continental and oceanic crust. Most of the oceans are very, very deep. I wouldn't go that far, but certainly, the world is one place and it's often better to emphasize connections rather than divisions.

Brian Lehrer: Professor Martin Lewis, professor emeritus from Stanford, whose 2010 article was called How Many Continents Are There? Thank you very much for joining us. I think we cleared this up, and yes, we did give that caller a hat. 

Martin Lewis: Thank you very much.

Brian Lehrer: That's The Brian Lehrer Show for today produced by MaryEileen Croke, Lisa Allison, Amina Srna, Carl Boisrond, and Esperanza Rosenbaum. Zach Gottehrer-Cohen edits our National Politics Podcast. Our intern is Ethlyn Daniel-Scherz. We had Shayna Sengstock at the audio control. Stay tuned for All Of It.

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