Wind back 1,000 years and the moral landscape looks very different to today. Most farming societies thought slavery was natural and unobjectionable, premarital sex was an abomination, women should obey their husbands, and commoners should obey their monarchs.

Wind back 10,000 years and things look very different again. Most hunter-gatherer groups thought men who got too big for their britches needed to be put in their place rather than obeyed, and lifelong monogamy could hardly be expected of men or women.

Why such big systematic changes — and why these changes specifically?

That's the question bestselling historian Ian Morris takes up in his book, Foragers, Farmers, and Fossil Fuels: How Human Values Evolve. Ian has spent his academic life studying long-term history, trying to explain the big-picture changes that play out over hundreds or thousands of years.

Rebroadcast: this episode was originally released in July 2022.

Links to learn more, highlights, and full transcript.

There are a number of possible explanations one could offer for the wide-ranging shifts in opinion on the 'right' way to live. Maybe the natural sciences progressed and people realised their previous ideas were mistaken? Perhaps a few persuasive advocates turned the course of history with their revolutionary arguments? Maybe everyone just got nicer?

In Foragers, Farmers and Fossil Fuels Ian presents a provocative alternative: human culture gradually evolves towards whatever system of organisation allows a society to harvest the most energy, and we then conclude that system is the most virtuous one. Egalitarian values helped hunter-gatherers hunt and gather effectively. Once farming was developed, hierarchy proved to be the social structure that produced the most grain (and best repelled nomadic raiders). And in the modern era, democracy and individuality have proven to be more productive ways to collect and exploit fossil fuels.

On this theory, it's technology that drives moral values much more than moral philosophy. Individuals can try to persist with deeply held values that limit economic growth, but they risk being rendered irrelevant as more productive peers in their own society accrue wealth and power. And societies that fail to move with the times risk being conquered by more pragmatic neighbours that adapt to new technologies and grow in population and military strength.

There are many objections one could raise to this theory, many of which we put to Ian in this interview. But the question is a highly consequential one: if we want to guess what goals our descendants will pursue hundreds of years from now, it would be helpful to have a theory for why our ancestors mostly thought one thing, while we mostly think another.

Big though it is, the driver of human values is only one of several major questions Ian has tackled through his career.

In this classic episode, we discuss all of Ian's major books.

Chapters:

• Rob's intro (00:00:53)
• The interview begins (00:02:30)
• Geography is Destiny (00:03:38)
• Why the West Rules—For Now (00:12:04)
• War! What is it Good For? (00:28:19)
• Expectations for the future (00:40:22)
• Foragers, Farmers, and Fossil Fuels (00:53:53)
• Historical methodology (01:03:14)
• Falsifiable alternative theories (01:15:59)
• Archaeology (01:22:56)
• Energy extraction technology as a key driver of human values (01:37:43)
• Allowing people to debate about values (02:00:16)
• Can productive wars still occur? (02:13:28)
• Where is history contingent and where isn’t it? (02:30:23)
• How Ian thinks about the future (03:13:33)
• Macrohistory myths (03:29:51)
• Ian’s favourite archaeology memory (03:33:19)
• The most unfair criticism Ian’s ever received (03:35:17)
• Rob's outro (03:39:55)

Producer: Keiran Harris
Audio mastering: Ben Cordell
Transcriptions: Katy Moore