The Cyclical Development: Ice Ages and “Great Leaps” Have Shaped Man

This article was published on November 14, 2024.

The Cyclical Development: Ice Ages and “Great Leaps” Have Shaped Man

Abstract

I have previously proposed a Copernican revolution in our understanding of human evolution (Abrahamsson, 18 May, 2024). In this article, I outline a broader developmental scheme for humanity, suggesting that we have undergone several great leaps, not just the one occurring 40,000 years ago. Historically, human development has not been about increasing creativity but about enhancing our ability to imitate and replicate behaviors established by our ancestors. Homo sapiens was thus originally a bodily materialization of an old way of life—an old survival strategy—that had been acquired by their predecessor, Homo heidelbergensis.

All standard models in human evolution have been extremely conservative. In their original form, all human species, including our own, have been deeply tradition-bound and produced standardized tools. It was the same Homo erectus who, at the beginning of their existence, manufactured Oldowan tools, later developed the Acheulean culture, and learned to make fire (Gowlett, 2016). The same Homo heidelbergensis who, 600,000 years ago, created standardized hand axes and, 400,000 years ago, developed the Levallois technique. The same Neanderthals who, 400,000 years ago, used tools similar to their predecessors, and around 160,000 years ago developed the Mousterian culture, began burying their dead, and created cave paintings. Likewise, Homo sapiens, who 300,000 years ago manufactured standardized Middle Stone Age tools, began 40,000 years ago to create microlithic tools, make sculptures, and spread across the globe.

Our evolution has followed a cyclical pattern, with climate changes like ice ages prompting periods of cultural innovation and biological adaptation. Each time we faced drastic environmental shifts, our latent creative abilities were awakened to develop new survival strategies. Language, which was originally a tool for imitation, became free in this process and created opportunities for symbolic thinking and social organization.

The advent of agriculture drastically changed the scene, as we gained the ability to fundamentally alter our environment. This development sheds new light on our situation today. With the power to reshape nature, there seem to be no limits; we strive to break all boundaries and even aspire to live forever—a sentiment most prevalent in technological hubs like Silicon Valley. In our pursuit to transcend natural constraints, we have become dangerously lost.

Introduction

I have proposed a Copernican revolution (Abrahamsson, May 18, 2024). Human evolution has not moved toward increased creativity but toward an improved ability to imitate and replicate behaviors already acquired by our ancestors. The brain, with its linguistic structures, became larger to consolidate specific behaviors rather than to create new ones.

Tools have played a crucial role in human evolution by enabling adaptation to new and unfamiliar environments. With the help of tools, our ancestors were able to extract energy from environments that would otherwise have been inaccessible. Tools can be seen as an extension of the body—an exosomatic organ (Leroi-Gourhan, 1983) in the form of, for example, a more powerful arm or harder claws. Through tools, humans could exploit unimagined resources and overcome their biological limitations. In this way, tools functioned like a respirator, allowing humans to survive and thrive in environments they were not biologically adapted to.

With the help of latent creative ability and the development of tools, humans were able to adapt to new environments. In evolutionary biology, there is the concept of an Evolutionarily Stable Strategy (ESS), which means there exists a way of life, a particular strategy, that outperforms all others in a stable environment. After some time, humans created an artificial adaptive peak or an ESS, which meant the need for innovation decreased, and they lived in a stable way again. This, in turn, led to an intense development of the brain—it can be said that human biological development progressed toward an adaptive peak already achieved through their own actions. Behaviorally, but not biologically, humans were adapted to the environment. By developing structures and language instead of cumbersome instincts, humans were able to adapt to this adaptive peak. In this way, they could become anchored in the environment and live stably—in the fastest possible time. The individuals who best specialized in the environment also became more successful in spreading their genes. Simultaneously, bodily adaptations to the new environment occurred.

Homo sapiens was thus originally a bodily materialization of an old way of life—an old survival strategy—that had been acquired by their predecessor, Homo heidelbergensis. This means that the first Homo sapiens individuals were more fixed and bound than the last specimens of Homo heidelbergensis. The development from Homo heidelbergensis to Homo sapiens involved, in addition to an increased brain volume, a lighter and more agile physique, smaller jaws and chewing muscles, less robust bones, and more (Stringer, 2016).

The growth of the brain was necessary to overcome the contrast between humans and their environment. With the help of language and mirror neurons, the brain consolidated this new survival strategy. The original function of language was to imitate behaviors and refine the use of tools; you could say that language was the superstructure of tools. Evolution turned culture into camouflaged nature.

A Cyclical Development

This reasoning raises a pertinent question: Does this not mean that Homo heidelbergensis must also have lived in an uncertain way at some point in the distant past? Doesn’t all this suggest that our ancestor, discovered in the German city of Heidelberg, must have originally lived in an unfamiliar environment and adapted to it, only to settle down and specialize in this way of life—just like our own species?

Yes, that is exactly what we must assume. My theory posits that human ancestors must also have lived in unfamiliar environments and, with the help of tool innovations, managed to remain in the new biotope and adapt.

So far, we have focused on the evolution from Homo heidelbergensis to Homo sapiens, which occurred between 600,000 and 300,000 years ago. But we must delve much further back in time to understand human development in its entirety. The same should apply to the ancestors of Homo heidelbergensis and their predecessors, and so on. This includes Homo erectus, Homo habilis, and probably even the common ancestor of humans and chimpanzees.

Human evolution is reversed. We must—if the theory holds—fundamentally change our view of humanity’s development. The evolution of our ancestors must be examined with new eyes.

All standard models in human evolution have been extremely conservative. In their original form, they have all, including humans themselves, been extremely tradition-bound and produced standardized tools. It was the same Homo erectus who, at the beginning of their existence, manufactured Oldowan tools, later developed the Acheulean culture, and learned to make fire (Gowlett, 2016). It was the same Homo heidelbergensis who, 600,000 years ago, created standardized hand axes and, 400,000 years ago, developed the Levallois technique (Boëda, 1995). It was the same Neanderthals who, 400,000 years ago, used tools similar to their predecessors, who around 160,000 years ago developed the Mousterian culture and later began to bury their dead and create cave paintings (Pettitt, 2011). It was the same Homo sapiens who, 300,000 years ago, manufactured standardized Middle Stone Age tools, and 40,000 years ago began to create microlithic tools, make sculptures, and spread across the globe (McBrearty & Brooks, 2000).

Paleoanthropologists are puzzled by these findings. They stack cranium upon cranium but have no way to fully understand them. The same uncertainties that characterize research on Homo sapiens also characterize research on our ancestors.

Thus, there has not only been one great leap but several. The “Great Leap Forward” of Homo sapiens 40,000 years ago was not a unique event but a repetition of a very old phenomenon.

We can say that human development has been cyclical. Humans have moved in and out of different biotopes and adaptive peaks. During certain periods, they lived within the biotope, only to be cast out from it. We can see that human development follows a particular pattern: first, a climate change occurs, then a cultural change, and thereafter a biological change.

Every time there has been a biological evolution, humans have become better at imitating and repeating the behaviors of their ancestors. Biological evolution is synonymous with adaptation to a specific environment. But every time this development has taken place, the brain has also become larger—and the ability to handle similar stresses in the future has increased. Humans have thus evolved in the same way as other animals—in the direction of a specific biotope.

Mirror neurons have played a central role in this. Mirror neurons are nerve cells that activate both when we perform an action and when we see someone else perform the same action. This is especially true for hand movements and other motor activities that are central to tool use and social interaction. Although other animals also have mirror neurons, such as primates and certain bird species, the human mirror neuron system is more developed and complex, which has enabled a higher degree of imitation and social learning (Arbib, 2012).

Through mirror neurons, we can directly understand and internalize others’ behaviors without relying on slow genetic changes or purely instinctive responses. This ability has allowed us to quickly transfer knowledge and skills between individuals and generations.

Intelligence has functioned as a self-winding clock. Even Darwin had this notion, but there is an important difference. While Darwin believed that intelligence continually increased with the purpose of being used (Darwin, 1871), I argue that intelligence has been continuously buried—but the latent creative ability has grown.

Man is a result of the ice ages. The recurring ice ages that began during the Pleistocene about 2.6 million years ago coincide with the emergence of the genus Homo and served as the engine in this self-winding process. When ice masses expanded and retreated in vast cycles, it was humans, among all the animals nearby, who could tackle the new conditions and often remain in the same geographical location without necessarily following the retreating biotope.

Each developmental stage can be linked to a specific climate change. The emergence of Homo habilis and Homo erectus coincides with two significant ice ages that occurred approximately 2.8–2.5 million and 1.9–1.7 million years ago, respectively. Around 800,000–600,000 years ago, significant climatic variations occurred during the so-called Middle Pleistocene Transition, which coincides with the emergence of Homo heidelbergensis (Chilson et al., 2017). During ice ages, large amounts of water are bound in polar ice caps and glaciers, leading to shrinking rainforests while savannas and desert areas expand (Chilson et al., 2017).

Now we also have the solution to the explosive development of humans. The reason evolutionary leaps have been able to occur so quickly, for example from Homo habilis to Homo erectus, is that humans lived in an artificial adaptive peak. The traits that would be selected were already determined since the way of life had long been established.

In this way, we can also explain the emergence of bipedalism. Through the use of tools, humans could extract energy from environments to which they were not biologically adapted, and the development toward bipedalism facilitated the use of these tools. Even if each step in the transition from quadrupedalism to bipedalism was not advantageous from a locomotor perspective (at least not during the time Homo sapiens spent on land), the benefits for tool use may have outweighed the disadvantages. The increased efficiency in tool use thus contributed to bipedalism becoming a successful adaptation despite its initial challenges.

Mental Abilities and Tool Development

Every time humans have managed to survive a climate change, they have become better at repeating the feat later. The greater the contrast between the way of life and biology, the more developed our linguistic abilities have become. The brain has artificially recreated and maintained an adaptive peak.

Other human mental abilities, such as consciousness, memory, spatial ability, and executive function, are also closely connected to the development of tools. These cognitive abilities enabled our ancestors to envision a finished tool from a large stone block, plan and execute a series of actions, navigate to specific locations in the landscape to find the right raw materials, and use the tools precisely. All this was accomplished without the language we know today.

The evolution of tools reflects this. The first Oldowan tools were so-called “pebble” tools, where the stone mass from which the tools were extracted resembled the final product (Toth, 1985). Later tools, such as the Acheulean tools, deviated significantly from the original stone mass, which required greater imagination and a better understanding of material properties (Wynn, 2002).

Even our so-called language center, Broca’s area, can be explained through tool use. As early as Homo habilis, developed regions in the brain corresponding to Broca’s area seem to have existed, which not only controls speech production but also the control of repetitive hand movements (Holloway, 1969). All these mental abilities are interconnected. Originally, tool use and speech—or rather singing—were simply expressions of the same thing: a methodical and meditative repetition of hand movements and movement patterns.

It is thus language—which originally had the function of facilitating imitation and guiding people in their tool use and daily life—that beneath the surface also gives rise to a creative and unbridled ability in combination with our other mental qualities. When language was freed, it led to us “waking up from a slumber”; we emerged from the fog that previously enveloped us, a recurring theme in many creation myths about humans, from Aboriginal cosmology to the Old Testament.

Here we also find the answer to the significant difference between humans and animals. The real difference crystallizes when humans are between two adaptive peaks—when language and creativity strive to create a new adaptation, when language is free and unstructured. This is why we experience a fundamental gap between us and animals. The difference is that they are adapted, while we are seekers.

In this perspective, the “human” can be seen as a liminal and rebellious force that turns previous norms and societal conditions upside down, while the “animal” is a conservative and consolidating force that promotes long-term adaptation and perfection.

When humans were forced to leave their adaptive peak and language lost its imitative and reproductive role, free language emerged—the symbolic language. In combination with our other mental abilities, such as consciousness, spatial perception, and executive function, humans could develop new survival strategies, tools, and a new social organization.

But in this liminal phase, humans also experienced a split between the inner and the outer, or between body and soul. They left the soothing fog they had previously inhabited; they lost their equilibrium. When they adapted to the new conditions and created a new adaptive peak, stability arose again, and with it, an inner peace. This state of inner division and the quest for balance is also reflected in many animistic religions, notably among several of South and North America’s indigenous peoples, where humans are seen as children who need to learn adaptation and stability from the wise animals (Harvey, 2013).

Why Only Humans?

One may ask why only humans have evolved in this way. Why haven’t other animals, which have also endured climate changes, evolved similarly? The reason is simply that animals have not been able to abandon their biotope. When the biotope has disappeared, the animals have followed it. Animals have not had the opportunity to abandon their inherited way of life in the same way humans have.

Only humans (possibly with the exception of chimpanzees) have been able to enter this self-winding process, which requires freeing the hands to manipulate the physical environment. This process probably began around 15 million years ago when Earth was the planet of the great apes, and lush rainforests stretched from Africa to Southeast Asia. There were about 20 species of large hominids during this time, but five million years later, only two evolutionary lines remained: one in Africa, which would give rise to chimpanzees, gorillas, and humans, and one in Asia leading to the orangutan (Begun, 2003).

The foundation for the great apes’ significant creative adaptability was likely laid here. But it was only human ancestors who repeatedly lived in changing environments and, as a result, became increasingly proficient at extracting energy from their surroundings using tools—as evidenced by our highly refined thumb and precision grip (Marzke, 1997).

In his time, the renowned ethologist Konrad Lorenz was amazed by the flexibility of young chimpanzees. He perceived their behaviors as signs of a bygone intelligence, suggesting that chimpanzees once possessed a higher degree of creativity and adaptability than observed in their adult counterparts. According to Lorenz, the chimpanzee juveniles hinted at an ancient and more creative past, where their flexibility reflected an earlier evolutionary potential no longer as prominent in adult chimpanzees (Lorenz, 1966).

But how can this be explained? Why are chimpanzee juveniles so malleable when their parents are not? And why is there a latent creative ability in chimpanzees that doesn’t seem necessary in their daily lives? For example, it is exceedingly rare for wild bonobo chimpanzees to use tools (Whiten et al., 1999).

The answer lies in the fact that chimpanzees, at a historical stage, were significantly more malleable than they are today. Perhaps three to four million years ago, chimpanzees were more adaptable and had a greater latent creative ability. However, since this malleability was not tested, evolution moved toward more instinctive and automatic behaviors. During the Pliocene, chimpanzees remained in the rainforest, while humans had long since left it. Konrad Lorenz’s intuitive reflection may thus be correct.

Likely, all so-called primate calls (communication sounds among primates) were originally cultural innovations, but after many generations, they moved to the brain’s limbic system, becoming part of the biological apparatus. Today, these calls are often governed by emotional centers developed to handle social communication and immediate reactions (Seyfarth & Cheney, 2010).

Even the “hobbit” human (Homo floresiensis) can be an example of an evolutionary development that, over time, leads to a decreased latent creative ability. The hobbit human had a shrinking brain, similar in size to a chimpanzee’s, yet used fairly advanced stone tools inherited from their ancestors. Although this development may have been influenced by the hobbit human living isolated on an island—a phenomenon known as island dwarfism—it shows that humans can use tools even with smaller brains if development occurs in a stable environment over a sufficiently long time (Brown et al., 2004).

As we have seen, it is climate changes or drastically altered living conditions that have triggered the awakening of latent mental and linguistic capacity. This capacity has since been strengthened and developed through the cycles of the ice ages. But if stability lasts long enough, mental abilities will eventually wane, and more fundamental structures in the brain will slowly but surely take over these functions.

A New Perspective on Humanity’s Precarious Situation

Now we have gained perspective on what truly happened 40,000 years ago. The “Great Leap Forward” is no longer an inexplicable event. What occurred was simply that humans were forced to leave their biotope—and in connection with this, their intelligence and linguistic ability were stimulated.

These people abandoned an Evolutionarily Stable Strategy (ESS); they did not embark on an adventure. They were not innovators driven by a thrill-seeking gene, but unfortunate beings forced to leave Eden.

The “Great Leap Forward” was not an isolated event that happened by chance but part of an ongoing historical process. Homo sapiens was not the first human species to undergo such an upheaval but just one in a line of survivors. In fact, the “Great Leap Forward” was more or less inevitable—climate changes have recurred regularly, strongly influenced by variations in Earth’s orbit and tilt relative to the sun, known as Milankovitch cycles (Imbrie & Imbrie, 1986). So once humans had entered the self-winding process, it was more or less predetermined that modern humans, with their revolutionary qualities, would emerge.

We also know what aspirations these people had 40,000 years ago. They wanted to adapt; they wanted to mold themselves to nature and create an artificial adaptive peak. Humans experienced an inner split, well reflected in ancient mythologies. Adaptation was simply part of the quest for equilibrium, an inner peace.

Humans adapted. They created new tools, began sewing clothes, developed new hunting methods, transformed into big-game hunters, and learned to navigate the environment. If we strip away all culture, art, and symbolism, we see beings who adapted to unfamiliar environments, who, thanks to manipulation of the physical environment, managed to survive in surroundings where other species became extinct or were forced to retreat.

People were like foreign birds in a world they were not biologically designed for. Forced to live in an environment that wasn’t originally theirs, they still managed to adapt, thanks to a dormant creativity that awakened when most needed. They began building a new adaptive peak—just as their ancestors had done before. During this period, hundreds of species died out, including Neanderthals and a host of larger mammals, a development probably driven by both human progress and climate changes. Some indigenous peoples, such as the !Kung people of the Kalahari Desert and the Aborigines of Australia, however, managed to adapt to their respective environments and lived the same way for generation after generation, for thousands of years, until globalization one day swept over them and changed their world.

Agriculture: A Watershed Moment

In several places independently, agriculture emerged—not only in the Middle East but also in China, New Guinea, sub-Saharan Africa, Mesoamerica, the Andes, and eastern North America (Smith, 1998). With this, perhaps the greatest change in human history occurred. Previously, nature had always surrounded culture; it had set a limit and constituted a barrier to how much people could develop their culture. But through the domestication of animals and plants, the fundamental premises changed. Now, culture surrounded nature—we could change nature according to our own desires and wishes.

Modern humans want to overcome their limitations. They no longer wish to adapt but to transcend their biological nature. The physical restrains them—they want to overcome all obstacles of time and space. Everything should go faster and faster; they want to travel greater distances, gain more and more time, live longer, and revel in sensory impressions. Aging has become a limitation. They want to be constantly young, live forever, update themselves—something we see most clearly in Silicon Valley, the mecca of innovation.

Humans are still striving for equilibrium—but from the opposite direction. They want to soar like the wind over the globe and eliminate all limitations but do not realize that only a return to adaptation can fulfill this longing. Instead, they seek peace by eliminating all obstacles, by isolating themselves from nature as much as possible. Humans see no ceiling; they see no limits. They want out.

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