Cancer cells are characterised by uncontrolled proliferation, the ability to escape cell death, the capacity of “stealing” nutrients from the host, and finally to invade other tissues. Are we humans displaying similar features, in our own dimensional reality? If so, are cancers really a negative feature for the systems they develop within?
During the development of multicellular organisms, the division of a “mother” cell gives rise to two daughter cells. These cells keep dividing. At some point, they differentiate – they become specialised – and start forming tissues, groups of cells with a similar function. Organs, specialised macro-structures, are formed by multiple tissues, each of which has a particular function.
The development and growth of an organism is a fascinating – and rather precise – iteration of multiple cell divisions until an organism reaches its final size. This process actually never stops, as undifferentiated cells known as “stem cells” replenish tissues with new cells to substitute those that reach the end of their lifespan. This situation, which we would call “homeostatic”, is a situation in which cells keep dividing and differentiating, although the organism doesn’t grow in size.
Living organisms are not perfect. During their development, or even after they reach their final size, the genetic material contained in each individual cell can be damaged, generating DNA mutations. These mutations are caused by multiple factors, both environmental and intrinsic. An example of the former is the UV light from the Sun, which can cause DNA mutations. An example of an intrinsic factor is an error from one of our cellular machineries that have the task of replicating our DNA each time cells divide.
When a mutation arises, most of the time cellular repair machineries are able to “fix” the damage. Sometimes, however, this does not occur and mutations occasionally affect important genes, which are critical for the regulation of cellular divisions.
As we mentioned, cellular divisions are very important for the growth of an organism, as well as to replace dying cells from a tissue when an organism has finished growing.
We can imagine that, once those important elements necessary for the proper division of cells are no longer functional – because of the aforementioned mutations – cellular divisions become uncontrollable. This can potentially result in the formation of a tumour. From being a specialised entity, the cancerous cell becomes a “non-specialised” cell, capable of proliferating without restrictions.
Cancer is indeed a disease caused by the uncontrolled proliferation of cells.
But how do we define a cancer? What are its characteristics?
We have already defined the first one: uncontrolled proliferation. Cells stop following “the great plan”. Among the “hallmarks of cancer” (1), we also find that cancer cells don’t die, they evade “apoptosis”. Apoptosis is a word that comes from ancient Greek, and stands for “falling off”. It is a mechanism of programmed cell death. Each healthy cell of any organism, when necessarily, undergoes a regulated process of death, so that the individual constituent of the cell can be re-used by other cells to sustain their activities. Cancer cells, however, do not die. They stop those intrinsic mechanisms that lead to apoptosis.
In order to divide, cells require a huge amount of energy, and cancer cells are no exception. To circumvent this problem, cancer cells promote “angiogenesis”, another hallmark of cancer (1). Basically, through the release of certain molecules, cancer cells are able to promote the formation of blood vessels that supply the tumour mass with nutrients. They build preferential “roads” for the cancer, stealing nutrients from the host in order to sustain their own growth.
The last hallmark is the ability of a tumour to invade other tissues and metastasise. When cancer cells accumulate additional mutations (to those that “made” them a cancer), they lose contact with the neighbouring normal cells and start moving freely, detaching from their original location, entering blood vessels and reaching distant sites where they form a secondary tumour, called “metastasis”.
We have seen the main characteristics of a tumour. What we can learn from this scenario is that the self-centred strategy of cancer is advantageous to itself and disadvantageous to the system it develops within: the organism, or the “host”.
When a tumour grows without control, invading and metastasising, the host – for instance a human being – eventually dies.
This very fact underlines that, although advantageous for the tumour, this strategy functions in a short-term manner. In the long-term, this is a lose-lose situation, as the selfish cancer dies with its host.
Are we, humans, having similar characteristics to cancer within the dimension we live in?
Biological evolution is an ongoing experiment of mutations and fitness – the capacity of a species to adapt to a certain environment and survive. Different species are the outcome of random genetic mutations that result in more or less fit organisms. A species may acquire an additional feature that makes it less resistant to certain stressors within its surroundings, and thus it will disappear over time; it will go extinct.
Sometimes however, a mutation will provide an advantage to a certain species, making it able to better adapt to a specific niche, or even to survive in multiple environments.
Human beings are characterised by a substantially new – in evolutionary terms – feature: advanced intelligence, which includes the ability of abstraction.
This new and very advantageous characteristics made humans a very successful species.
All species are in principle competitive and individualistic within their own habitat. However their ability to affect shared ecosystems is rather limited because their mutual relationship remains in a competitive equilibrium. The success of human intelligence, instead, comes at a cost to the environment. We deeply comprehend our nature and pose ourselves existential questions, but also have a self-oriented and individualistic behaviour. The result is that we are able to expand in multiple niches, causing irreparable damage.
Similar to a tumour within a living organism, we have started to negatively affect the life of other species within the “organism” we live in, our dimensional world. Our environment is being strongly manipulated and negatively affected by our quest for progress and technology.
We solely rely on our intelligence to justify the fact we are the most important of the species, a gifted one. We have largely confused, during history, this purely biological feature with a divine gift, something that would give us the rights to explore, invade, metastasise.
Our vision of the future is relatively short. We hardly see what is coming ahead of us, because we use our complicated brain to answer immediate (and only immediate) questions. If we find a source of energy that makes us live in better conditions, we simply go for it. We don’t question it. We explore, discover, and make things our own. We basically use our intelligence as a way to sustain our short-term needs, but we lack a general vision of the consequences of our actions.
The “host” we live in – our natural environment – is being killed by our selfish, short-term strategy. If we look closely, we possess all the hallmarks of cancer:
- Uncontrolled proliferation – additionally caused by the emergence of a peculiar advantageous feature: our intelligence.
- Attempt to avoid death: progress and medicine make us live much longer than we would otherwise, and research keeps trying to find new solutions to further prolong our lives.
- “Human angiogenesis”: we “steal” nutrients and consume them, drastically weakening the planet we live in.
- We invade new territories, both physical and intellectual. We establish new niches, after a phase of exploration. What Greek mythology would define as “going beyond the Pillars of Hercules” (2).
The keyword here is self-perception, or self-understanding. The common element between humans and tumours is therefore their self-perceived individuality. Both don’t belong – anymore – to a harmonic natural system, but become the heralds of a new establishment, of a new order.
Some may raise the point that humans do not only have an individualistic mind-set as a species, but also as individuals. Humans are unable to cooperate in harmony, but rather fight against each other, for resources, space, and power.
Do the parallels with cancer still hold true? The answer is yes. The success of a tumour, its ability to proliferate and steal vital resources is not due to the cooperation between its cells. In fact, cancer cells are highly competitive among themselves as well. They fight over space and resources, as much as humans do within their system. It is well established indeed, that cancer cells accumulate many different mutations, and that within a tumour there co-exist several different sub-populations of cells (3). Some will be stronger than others. Some will be more “explorative” than others. Also, some will be deprived of the access to blood vessels. Some others won’t be able to proliferate, as they are “suffocated” by the growth of the fast-proliferating neighbouring tumour cells.
Cancer cells are in a constant competition between each other, exactly as we do as people.
Can we conclude that humans are a cancer? Yes, we are.
- Hanahan, D. and Weinberg, R.A., “The Hallmarks of Cancer”, Cell, 2000
- Homer, “Odyssey”
- Dagogo-Jack, I. and Shaw, A.T., “Tumor heterogeneity and resistance to cancer therapies”, Nature Reviews Clinical Oncology, 2018
Received: 28.04.19, Ready: 10.05.19, Editors: SR, RG.