Some people have asked me that, being a geologist, how did I end up writing a book on history? To me, geology is an extension of history and the two subjects are more inter-related than we think.
Geology deals with two different aspects: the living and the non-living. The rocks, mountains, minerals, plate-tectonics, etc, are the non-living part of geology that closely relate to geography. The living aspect, ironically, deals with the dead. Fossils and evolution to be precise. It is closely related to biology.
It is history that connects the two extreme aspects of geology. How? The short answer is: Geology influence history, history influence culture, and culture influence evolution. Let me explain.
Rifting in Africa is considered by many as the reason for the evolution of Homo sapiens. Plate tectonics created mountains that acted as barriers and thus natural boundaries of human civilisations. The rivers that came down from the mountains created fertile plains that became the nucleus for the growth of civilisations. Indian civilisation would not have been born without the fertile plain created by the rivers that exist because of the Himalayas. The melting of glaciers had a profound effect in starting the agricultural revolution. The long east-west axis of Eurasian plate, a result of plate tectonics, was the reason for the rapid growth of civilisation in the fertile crescent (read J. Diamond’s Guns Germs and Steel). The mineral deposits, coals and petroleum has influenced the geopolitics of the world. The mountains and passes have influenced the outcome of many battles. Geology, thus, played a big role in guiding the path human history took.
History’s influence on culture is more easily understood. Arts, languages, religions, nationalism and politics are outcomes of history that define cultures. Culture is unique to human beings if you define it, in a less minimalist way, as a complex social organisation where people learn shared way of life transmitted through symbolic forms of communication, like language. Unlike animals, culture binds a large group of people together through an idea that does not exist in reality. Languages are random vibrations whose pattern we associate with a certain meaning. The sounds are abstract as it does not have any real universal meaning. It’s meaning only exist in our mind once we are trained to do so. Language, however, creates bonds between a large group of people that defines a culture. Same is true for religion. It is an abstract concept that binds people together. It is a myth that exists only in our mind (read Sapiens by Y.N. Harari). It helps create an identity, a sense of unity, which has historically helped tribes to survive. Nationalism is also same as religion. Instead of an imaginary faith we now have imaginary borders that only exists in the human mind. Politics is no different. The leaders who create history, most often than not, are people who were able to incept any such mythical ideas in the minds of a large group of individuals. Individuals who were ready to fight and die for that idea. Ideas that resulted in numerous battles and bloodshed, ideas that annihilated Hiroshima and Nagasaki, ideas that now breed terrorism. We can say with some confidence that history and culture are intricately interlinked.
The link between culture and evolution is a bit more complex. Human beings accumulate ideas and technologies over generations and the culture evolves. Inventions like fire, or stone tools gave few groups of individuals advantage of survival. The groups that did not learn the new inventions perished, while the genes of those that survived dominated. Control of fire gave us the ability to cook food that became easier to digest. As a consequence our stomach, teeth and mouth became smaller and the intestine shortened. That might have helped us focus more energy towards the brain. There was a time when humans could not digest cow milk. Once we started domesticating cows our digestive system evolved in a way that it became easier to digest milk, or milk products. Cow milk became an easy source of protein and fat that gave the animal herders better chance of survival compared to hunters and gatherers. Thus, culture guides our evolution and decides which genes will spread.
Genes, in turn, control our behaviour, and thus culture. When I started having thyroid problems I noticed that I lost my temper very easily. I became a different person. It made me realise that a lot of what we are depends on the hormones that flow in our body. Those hormones, in turn, depend on our brain and thus our genes. How brains affect behaviour is well documented by the case of Phineas P. Gage (read Consilience by Edward O. Wilson). In 1848, Gage suffered a major accident in which he lost a part of his brain. The loss of that particular part of the brain, prefrontal lobe to be exact, turned a cheerful well-mannered gentleman into a self-destructive habitual liar. Similar cases have been observed with other people who lost that part of the brain. Prefrontal lobe, we now know, controls our emotions. When we judge people we often forget that most of the time they cannot help. Our culture, guided by our behaviour, is the result of our biochemistry.
That would mean something very interesting. The type of behaviour that would dominate the human race in the future would be guided by the genes that would spread. The genes that would spread would be the ones that control particular physical or behavioural traits in individuals that are preferred by the dominant culture at a particular time. These traits could be entirely imaginary bias/prejudice, like skin colour. Development of such prejudice is governed by historical events. An example would make things clear.
History of colonial rule can create a racist mindset that makes individuals prefer white skin. If the people in power, who had a better chance of survival, had white skin then a society like India can develop a preference towards that skin colour. In such a biassed society people having darker complexion would have less chance of getting married and thus spreading their genes. If the biassed culture continues long enough, soon that society would start getting fairer. For natural selection to be effective a cultural preference should persist for a long time. Thus, a historical event can create a biassed culture that, by the process of natural selection, directs the line of evolution. Lest we forget, the British colonised India because it had enough wealth that could make them rich. That wealth was a product of India's fertility and natural resource governed by the geology of India.
We tend to think of geology, history, biology, sociology, anthropology, genetics etc as entirely different subjects. When we think about it, these subjects are very much related. Being a geologist, it was only natural for me to get attracted to history. My current interest is in Dual inheritance theory (DIT), also known as gene–culture coevolution. And geology has a role to play there too.