In Our Time: The Columbian Exchange

BBC Radio 4 | Hosted by Misha Glenny | March 26, 2026

Overview

This episode explores the profound, multifaceted impact of the "Columbian Exchange"—the transfer of people, plants, animals, diseases, and ideas between the Americas and the rest of the world following Columbus’s 1492 voyage. Host Misha Glenny is joined by experts Rebecca Earl, John Lindo, and Mark Maslin, who dissect the demographic, ecological, culinary, cultural, economic, and climatic shifts that grew from this era-defining global encounter. The discussion highlights both devastation—particularly for indigenous Americans—and transformation, including the remaking of global diets, economies, and even the climate.

Key Discussion Points & Insights

The Scope and Consequences of the Exchange

• Defining the Columbian Exchange

  • Alfred W. Crosby's 1972 book popularized the term, but Mark Maslin prefers "The Great Dying" to emphasise the catastrophic indigenous population loss.

    "Calling it the Columbian Exchange feels rather benign. The reality was very different... Within 100 years of first contact with Europeans, 55 million out of those 60 million [Americans] were dead." — Mark Maslin (03:40)

• Population Before and After 1492

  • By 1492, population sizes of the Americas, Europe, and China were roughly equivalent (03:40–05:29). The introduction of Eurasian diseases led to demographic collapse in the Americas, with up to 90% mortality.

• Pre-Existing Movement and Civilizations

  • Ancient Americans had developed large empires, trade networks, and advanced agriculture, engaging in significant internal exchanges but remaining isolated transcontinentally (06:09).

Food, Health, and Cultural Exchange

• Why Europeans Brought Their Own Food

  • Beyond mere preference, health beliefs about the body and diet drove settlers to import familiar crops and livestock (07:16–08:53).

    "For them, lifestyle was really important to staying healthy... You can do something about the food." — Rebecca Earl (07:16)

• Skepticism Toward Indigenous Diets

  • Europeans attributed physical differences (e.g., lack of beards) to the diet of indigenous peoples, fostering suspicion towards American staples (09:05–10:29).

• New World Foods Transforming the Old World

  • The global impact was revolutionary: potatoes, tomatoes, maize, chillies, and more became dietary staples worldwide (10:38–11:56).

    "It's hard to imagine... Indian food without tomatoes, without chili peppers, without a potato..." — Rebecca Earl (11:08)

Disease Dynamics & Ecological Impact

• Pre-Contact Disease in the Americas

  • Tuberculosis (an endemic but distinct strain), H. pylori, and a variety of stomach and intestinal parasites existed pre-1492. "Paradise" narratives have been debunked by archaeology and ancient DNA (12:28–14:45).

• European Disease Catastrophe

  • Smallpox was the most devastating, followed by measles and influenza. Mortality rates were modulated by colony-driven societal disruption (15:12–16:59).

    "The mortality rates for smallpox were 30 to 50%. Where some other locales were reporting over 80% mortality rate." — John Lindo (15:12)

• The Little Ice Age Hypothesis

  • The collapse of indigenous farming led to vast land regrowth; this vegetation drawdown of CO2 likely amplified natural cooling during the "Little Ice Age," affecting global events such as mass famine and wars (17:19–19:19).

    "That regrowth was so large and so great that... around 1610, there's a big dip in CO2." — Mark Maslin (18:09)

Environmental and Agricultural Transformations

• Invasive Livestock and Soil Degradation

  • European cattle, sheep, and pigs proliferated in the Americas, destroying local ecosystems and causing long-term desertification (19:52–22:02).

    "Populations exploded...which ... led to desertification and soil erosion. And the land got poorer and poorer and poorer." — Rebecca Earl (21:03)

• Domesticated Animal Differences and Disease Transmission

  • Eurasia’s variety of domesticated animals gave rise to zoonotic diseases and shaped abilities to resist infection; the Americas’ limited domesticated fauna left populations especially vulnerable (22:04–23:01).

The Rise of Global Trade, Slavery, and Cash Crops

• Economic Restructuring

  • American crops like tobacco, sugarcane, and cotton became the foundation of global trade, facilitated by the devastation of indigenous labor and the rise of the transatlantic slave trade (27:04–28:30).

    "This is where the transatlantic slave trade originated. So over 350 years, something like 12 and a half million people from West Africa were transported across the Atlantic to work in the Americas..." — Mark Maslin (27:30)

• Sugar & Crop Geographies

  • The slave trade map overlaps almost precisely with sugarcane plantations; "drug foods" like sugar and tobacco, while caloric or desirable, provided little nutrition (28:51–29:36).

Lasting Dietary and Cultural Changes

• Dietary Innovations and Diffusion

  • Maize and cassava reshaped African diets; potatoes and chillies transformed Eurasian cuisine. Adoption often began with peasants, not elites (29:36–32:06).

• The Global Spread of Spices

  • Chilli peppers, found only in the Americas pre-1492, transformed food cultures across India, East Asia, and Indonesia (32:06–32:43).

    "It's only after the Americas that [spicy] curry becomes possible." — Misha Glenny & Rebecca Earl (32:06–32:43)

Indigenous Experience, Blended Cuisines, and Identity

• Nation-Building and Food
  • In the 20th century, Latin American countries celebrated hybrid cuisines as symbols of blended (indigenous, European, African) national identities (34:54–36:22).

    "Food often became a place where this blended nation was seen to be exemplified. Most countries... have some national dish which is said in some way to reflect this blended population. On a plate." — Rebecca Earl (36:08)

Humanity, Climate, and the Anthropocene

• The "Anthropocene Event"

  • Evidence of long-standing, intensifying human impact on climate—deforestation, methane from wet rice and cattle—culminated in the Industrial Revolution, signaling an epochal environmental shift (36:35–39:06).

• Contemporary Signs of the Exchange

  • Everyday diets and ecosystems remain stamped by the Exchange. Almost no modern meal is untouched by crops or animals first shuttled between continents 500 years ago (43:47–45:48).

Notable Quotes & Memorable Moments

• On Demography:
  "Within 100 years of first contact with Europeans, 55 million out of those 60 million were dead. That's over 90% of the population." — Mark Maslin (03:55)

• On Dietary Stereotypes:
  "Nobody in Europe had a bad word to say about the pineapple. Everybody thought pineapples were absolutely splendid." — Rebecca Earl (09:05)

• On Global Diets' American Roots:
  "It's hard to imagine...Indian food without tomatoes, without chili peppers, without a potato...no saag aloo!" — Rebecca Earl (11:08)

• On Disease Impact:
  "The mortality rates for smallpox were 30 to 50%. Where some other locales were reporting over 80% mortality rate. So incredibly devastating." — John Lindo (15:12)

• On Climate Feedback Loops:
  "That regrowth [of forests] was so large and so great that...around 1610, there's a big dip in CO2." — Mark Maslin (18:09)

• On the Blended Identity of Latin America:
  "Food often became a place where this blended nation was seen to be exemplified...a cosmic race unlike what you saw anywhere else in the world." — Rebecca Earl (36:08)

• On Modern Meals:
  "I doubt anybody listening to this program has had a meal that was untouched by the Columbian exchange in the last 24 hours." — Rebecca Earl (43:47)

Important Segment Timestamps

• [03:40] – The scale and reality of "The Great Dying"
• [07:16] – Why Europeans brought their own food, health and identity beliefs
• [10:38] – The transformation of world diets via American crops
• [12:28] – Diseases present in the Americas pre-Columbus
• [15:12] – Smallpox and mortality rates post-1492
• [17:19] – The Little Ice Age, land abandonment, and global cooling
• [19:52] – Impact and ecological consequences of introduced European livestock
• [27:04] – Cash crops, the slave trade, and economic restructuring
• [29:44] – Positive dietary changes, peasants as first adopters
• [34:54] – Culinary mixing and nation-building in Latin America
• [36:35] – The long arc to the Anthropocene
• [43:47] – The omnipresence of the Columbian Exchange in daily modern diets

Bonus: Noteworthy Expanded Discussions

The "Syphilis Exchange"

• Early modern Europeans believed syphilis arrived from the Americas, but modern DNA suggests the European strain was indigenous—that both continents had old, variant lineages (46:52).

Dogs in Colonialism

• Spanish powers targeted indigenous dog breeds to erase native cultures; John Lindo is researching the DNA of pre-contact American dogs to reconstruct their histories (40:39).

Earthworms as an Example of Ecological Colonisation

• European earthworms outcompeted American ones, symbolising how species redistribution created a "supercontinent" with decreased global biodiversity (41:56).

Ancient Migrations

• The peopling of the Americas likely occurred earlier than traditionally thought, with evidence pushing dates back to 25,000 years ago (49:18–52:31).

Key Takeaways

• The Columbian Exchange was not a benign swap, but an epochal event of demographic catastrophe, ecological transformation, and culinary revolution.
• Nearly every modern meal is a legacy of the exchange, for better and worse.
• The transference of crops, livestock, pathogens, and people reverberates in culture, economics, and the environment to this day—a legacy still visible, and still deeply contested.

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