---
title: "Dan Mrejeru's Speakingman: A Geologist's Theory on the Evolution of Human Intelligence"
description: Romanian-born independent researcher Dan Mrejeru releases the seventh edition of The Speakingman, arguing planetary cooling and geomagnetic excursions produced human intelligence.
author: Dr Marina Nani (Editor-in-Chief)
date: 2026-04-17T14:09:56.657Z
updated: 2026-04-17T14:09:56.675Z
canonical: https://richwoman.co/article/dan-mrejeru-speakingman-evolution-human-intelligence
image: https://cdn.nanimediahouse.com/mrejeru-featured-final.webp
categories: Science & Tech
content_type: Book Review
publication: Sovereign Magazine
about:
  - type: Person
    name: Dan Mrejeru
    description: Romanian-born geologist, geotechnical engineer and independent researcher based in the United States. Author of twenty books including The Making, the Rise, and the Future of the Speakingman. MS in Geology, University of Bucharest (1975). Affiliated with the American Association for the Advancement of Science. Top 2% on academia.edu with 100+ papers and readers in over 2,000 universities across 154 countries.
    url: https://danmirceamrejeru.com
    jobTitle: Independent Researcher & Author
    sameAs:
      - https://independent.academia.edu/DanMrejeru
      - https://www.amazon.com/stores/Dan-M.-Mrejeru/author/B09QSDG1C3
---

Dan Mircea Mrejeru is not the kind of person who usually gets to reopen the question of how humans became human. He trained as a geologist in Bucharest in the 1970s, left Romania for the United States in 1985, and spent the next thirty-five years running a geotechnical engineering firm in which soil, rock and bearing capacity were the daily problem. In the evenings, over more than two decades, he wrote twenty books on the origin of the human mind.

The latest is the seventh edition of *The Making, the Rise, and the Future of the Speakingman*, released this month through his own imprint, A Terrestrial Mind Publishing. The sixth edition won a Literary Titan Gold Book Award earlier this year, Mrejeru's sixth Gold across the series and its companion works. The seventh adds more than a hundred pages on a single idea: that the evolution of human intelligence was driven, above all, by the cooling of the planet.

### Book: The Making, the Rise, and the Future of the Speakingman
*Seventh Edition*
By Dan Mrejeru

The Speakingman argues that human cognition and language did not emerge through gradual Darwinian selection alone but through environmental shocks. Geomagnetic excursions, atmospheric radiation events and climatic cooling drove bursts of neurogenesis that rewired the hominin brain across two discrete cognitive leaps. The seventh edition adds a new Part on Planetary Thermal Cooling, proposing that long-term cooling of the planet was the permissive condition that allowed larger brains to evolve without fatal metabolic costs, and a discussion of the Information Society and the need for a deliberately cultivated hybrid mind in the age of AI.

[Amazon](https://www.amazon.com/Making-Rise-Future-Speakingman-development/dp/B0GWFF83ZJ/)

## The outsider scholar

Most theories of human origins are produced inside universities by paleoanthropologists, linguists or evolutionary biologists. Mrejeru belongs to none of those tribes. He describes himself, in the post-scriptum of the sixth edition, as "an independent researcher in multidisciplinary domain," affiliated only with the American Association for the Advancement of Science, whose method is to read across fields until a pattern surfaces and then test whether the pattern has a cause.

His academia.edu profile, where he has uploaded more than a hundred papers, places him in the top two percent of users on the platform, with readers in over two thousand universities across one hundred and fifty-four countries. The book series is the distillation of that reading. Each edition swaps in new evidence and, when a chapter grows to critical mass, a new Part. In this sense The Speakingman is less a finished book than a living manuscript that Mrejeru has been revising in public since the early 2020s.

## Two leaps, not one

At the core of the Speakingman thesis is the argument that *Homo sapiens* [did not slide gradually into language](https://www.sovereignmagazine.com/article/genes-of-the-past-christer-jansson-lost-sense). Mrejeru proposes two discrete cognitive leaps. The first, roughly five hundred thousand to three hundred thousand years ago, reorganized the cerebellum and the frontoparietal cortex and produced the anatomically modern hominin brain. The second, between one hundred thousand and twenty-seven thousand years ago, rewired that brain again into what he calls the Speakingman: a creature whose defining feature is not tool use or upright walking but speech.

The mechanism he proposes for both leaps is unusual. Mrejeru argues that geomagnetic excursions, moments when Earth's magnetic field weakens or wobbles, allowed bursts of cosmic radiation to reach the atmosphere. That radiation raised levels of carbon-14 and reactive oxygen species, which in turn triggered neurogenesis, the creation of new neurons. "Neurogenesis," he writes in the opening abstract of the seventh edition, "was solely responsible for producing encephalization, new cerebellar and frontoparietal structures and significant [circuitry reorganizations in the brain](https://www.sovereignmagazine.com/article/written-in-white-matter-your-native-language-designs-your-brain-and-makes-you-unique)." The brain, in this reading, is not only a biological organ. It is a geophysical artifact.

## Why cold climates made smarter minds

The new fifth Part of the seventh edition, titled Planetary Thermal Cooling, is where Mrejeru makes his most ambitious move. He argues that all of the mechanisms above, the excursions, the radiation, the oxidative stress, sit underneath a deeper driver: the long cooling of the planet. Between roughly fifty-five million years ago and three hundred thousand years ago, the Earth's average surface temperature fell by more than twenty degrees. That cooling, he writes, "allowed for increased brain size without fatal metabolic costs of overheating, permitting the addition of new neurons and more computing power."

From this he proposes what he calls a cognitive comfort zone, a band of roughly twenty to twenty-six degrees Celsius in which the human brain does its best work. Glacial periods, in his reading, favored nonlinear thinking, insight and intuition, and drove brain expansion. Interglacials, including the one we are currently in, favor linear thinking: lists, quantification, spreadsheets. It is not a flattering diagnosis of the modern mind. If his framing holds, warming climates may begin to reverse the expansion that cooling produced. The question of why human brains got bigger, in other words, has a sibling question that Mrejeru thinks we are not yet asking out loud.

## The Information Society problem

Part Six turns to the present. The sixth edition added a long new discussion of what Mrejeru calls the Information Society, and the seventh expands it. His argument is that by [outsourcing memory, pattern-recognition and analysis to machines](https://www.sovereignmagazine.com/article/ai-answers-too-quickly-and-it-might-be-changing-how-we-think), human cognition is collapsing out of its nonlinear mode and into an increasingly flat, linear one. Context, empathy and insight, the faculties that cold climates produced, are the ones most at risk.

His prescription is not Luddite. It is an argument for deliberate cultivation of what he calls a hybrid mind. "It becomes mandatory," he writes on the final pages of the seventh edition, "that humanity adopt a hybrid state of the mind, which if it does not evolve naturally, it must be implemented in an artificial way." A geologist who spent the first half of his career holding up buildings has ended up, in the second half, holding up a warning about the architecture of thought.

## A living book

The Speakingman dedication is to three people. The first is Spiru Haret, the Romanian mathematician and education reformer who helped lay the groundwork for nonlinear dynamics in the nineteenth century. The second is Mrejeru's grandfather Leon, who built more schools in interwar Romania than any other figure of his generation. The third is his daughter Anamaria, a neuroscience postdoctoral researcher whose work, Mrejeru writes, is the reason he began reading into brain evolution in the first place. Three generations of teaching sit inside the book's acknowledgements page, which reads, in its quiet way, like a family argument about what the mind is for.

The seventh edition is available in hardcover and on Amazon Kindle. It is not an easy read. It is also, on the available evidence, the most sustained attempt anyone has made to treat human intelligence as a geological phenomenon.

**About Dan Mrejeru**
Independent Researcher & Author

Romanian-born geologist, geotechnical engineer and independent researcher based in the United States. Author of twenty books including The Making, the Rise, and the Future of the Speakingman. MS in Geology, University of Bucharest (1975). Affiliated with the American Association for the Advancement of Science. Top 2% on academia.edu with 100+ papers and readers in over 2,000 universities across 154 countries.

[Website](https://danmirceamrejeru.com)

## FAQ

**Q: How did climate change shape human evolution?**
Paleoclimate data shows Earth's average surface temperature fell by more than twenty degrees Celsius between fifty-five million years ago and three hundred thousand years ago. In Mrejeru's reading, that long cooling allowed larger brains to evolve without the metabolic cost of overheating, with neuron counts peaking around one hundred thousand years ago. The Mid-Pleistocene Transition, which lengthened glacial cycles from forty-one thousand to one hundred thousand years, coincides with the second of the two cognitive leaps he describes.

**Q: When did humans first speak language?**
The Speakingman argument places the decisive rewiring of the modern brain between roughly one hundred thousand and twenty-seven thousand years ago, which is also the window in which fully modern language is thought to have emerged. Mrejeru treats the two as the same event rather than separate ones, proposing that neurogenesis driven by environmental shocks produced the circuitry on which language runs.

**Q: What happened during the Cognitive Revolution?**
The phrase, popularized outside academia by Yuval Noah Harari, refers to the burst of symbolic thought, art and language that shows up in the archaeological record roughly seventy thousand years ago. Mrejeru identifies it as the tail end of the second of his two cognitive leaps and attributes it not to a random mutation but to a sustained pulse of neurogenesis triggered by geomagnetic excursions and atmospheric carbon-14.

**Q: Why did human brains get bigger?**
Mainstream explanations cite cooking, social group size and dietary shifts. Mrejeru's answer, set out in Part Five of the seventh edition, is that planetary cooling was the permissive condition that made size increases metabolically possible, and that geomagnetic excursions were the trigger that produced the actual bursts of new neurons. Remove either factor, he argues, and the expansion does not happen.