Molecular biology had its triumphal start with 1953 Watson and Crick discovery of the DNA double helix, and the illuminating view that this structure permits to understand the two main functions of DNA, namely the self-replication, and the expression of proteins (Figure 4). From that point on, DNA has been the major hero not only in the scientific biology, but also in mass media – becoming a kind of icon for life itself. The advance in the lab technology, which has brought to the human genome, and to countless exciting news in the field of bio-engineering (up to the recent work with the so-called CRISPR/cas9) keeps maintaining the high degree of interest.
There is however a social and cultural aspect of this situation, which tend to transform this interest in a kind of gene-centered reductionism. In the simple-minded journalistic mass media, there is often a direct relation between one gene and one particular behavior trait, or between one gene and one specific disease – and you find expressions such as the gene of obesity, the gene of alcoholism, the gene of longevity, and so on. The absurdity of this position has been emphasized several times, see among others the book by Capra and Luisi (2014), the one by Denis Noble (2006), not to mention the classic book by Evelyn Fox Keller, The century of the gene (2000).
It is difficult to dispel from mass media the fallacious idea that DNA is equivalent to life. Actually, as I have mentioned often (see also my books, like The Emergence of Life, 2016) I believe that the equation “DNA (or RNA) = life” has been detrimental to the research in the field of the origin of life – and to research on the general question “what is life?”.
Even the idea that DNA alone is capable of self-replication is fallacious: DNA alone does not do anything. Only in strict cooperation with several enzymes, DNA can self-replicate and can arrive at producing RNAs and proteins (see Figure 4). And this, is not yet life. In addition, since years, also the very base of the old dogma of molecular biology – “one gene – one protein” has been recognized to be incorrect. And even more incorrect is the idea “one gene – one function”, meaning for function for example a disease, or a trait of behavior.
Simple disease or any complex function is determined by a large number of interacting genes and proteins, so that we should always have in mind a network of genes and proteins always connected with each other in a large net. Given this complexity, it is understandable that the mass media tends to simplify the picture, but this generates a series of misconceptions.
Not that DNA is not relevant, of course, but its relevance needs to be understood in terms of systems biology, according to which it is the organism itself that determines which genes will be read and expressed. It is a top-down more than a bottom-up view, as shown in Figure 6. This comes from Noble’s book, showing the linear chains of causality going from the genes to the function (the reductionist/deterministic view) and how this should be modified by feedback controls coming from the higher levels of organization.
Now, having expressed all these objections against the DNA-centered view, it should not appear a contradiction to see here the tree of life (Figure 1) – which shows that a gazelle is different from a lion because of a different genome. This is an important point: to say that the lion and the gazelle differ because of their genome, and that correspondingly they have a different behavior, is not sociobiology, is not a DNA-centered view: it is simply biology and Darwinism. In fact, the lion differs from the gazelle due to a different evolution history, a pathway that, although coming from a common mammal ancestor, is the product of innumerable genetic variations that in the course of millions of years brought to a quite dramatic difference of form and behavior.
This is of course true also for mankind, and in the following we will dwell, although rapidly, on the genetic determinants of man – what makes man genetically and/or different from other animals.
The killing-ape instinct
One of the first questions that comes to mind concerns the aggressive nature of humans, as witnessed by thousands of years of bloody wars and killing. In the history of humans, never a year has passed without events of war, murder and destruction.
Is this the result of a genetic trait? Are we genetically determined to be aggressive, to make wars and kill each other as a kind of genetic damnation of our being humans?
This question is made reasonable by the observation that many other animal species do not behave in such a way. They may kill each other to defend territoriality or their partners, but they do not gang together in ferocious raiding groups to attack in a predetermined action another group of animals of the same species. In an interesting book, Demonic Males (1996), anthropologists Wrangham and Peterson studying aggressive behaviours of apes and humans, arrive at a hard conclusion: only humans and chimpanzees are “killing apes”, who have the habit or at least the capability of organizing themselves in male-bondage teams with the aim of killing in a cold-blooded way other individuals of the same species. Humans and chimpanzees diversified from each other only ca. 5-6 million years ago, see Figure 3.
Where does the original killing habit come from? One can argue that, contrary to other animals, man is not provided with claws, horns, strong skin, wings to fly away. Thus, the only way to arrive at food was to kill other animals – or other men – using skilful intelligence. How could they otherwise survive? Not an ethical consideration – in nature all animals eat other animals – but one based on the necessity of survival. Again arguably, the origin of this genetic trait must also be based on the environment in which our common progenitor, 5-6 million years ago, was living, as the other apes did not develop this killing aggressiveness. Probably these ancestors lived in a very poor environment, where the only survival way was killing of other animals, including perhaps cannibalism. The environment appears to have played an important role also in the development of the behaviour of the bonobo, see Figure 5 and the corresponding figure legend.
More in general, coming back to the two already mentioned anthropologists, Wrangham and Peterson, they refuse the notion that, on our planet, there are or there have been peaceful, idyllic places without violence. They are expressing also the view that violence is not a general human characteristic, but rather a specifically male human characteristic. To this determinant of aggressiveness we also may add all other negative emotions such as anger, hate, or jealousy. Let us also say, however, that this aggressiveness is not the only determinant of our being human. There is also the opposite trait of love and altruism, to which we will gladly turn.
Love and altruism
Love is certainly a very fundamental aspect of animal behaviour. Obviously, love of the mother for her puppies can be seen as the main device provided by nature for the preservation of species, and love and sexual attraction between males and females can also be seen in this light, as the best way to warrant reproduction. In humans, love can also be seen as instinct, but it comes together with consciousness and moral codes (we will come back to this later on).
To say that love is genetically determined does mean to negate or diminish its beauty in all its many wonderful manifestations, nor to diminish the cultural and artistic aspects brought about by our civilization in our conception of love. And the same is true for altruism. There is a vast literature on altruism and cooperation within the Darwinian scientific literature, dealing with symbiosis and many other aspects upon which we cannot dwell here. Suffice to say that altruism, cooperation, and love can be linked to natural selection: groups, tribes or social structures that were characterized by altruism and cooperation had better chances of survival. This is certainly an important aspect of our being human.
There is an important difference between love in humans and love in other animal species – the difference being due to certain aspects of human consciousness. In Buddhism, for example, but also in other religions, there is a lot of emphasis on compassion, understood as the active desire of feeling the suffering of others and of helping them.
To this subject of love and altruism, one should add positive emotions like joy, happiness, gratitude, euphoria, and hope – as well as positive feelings, such as feeling satisfied, sympathetic, or fulfilled. Figure 2 gives a simple-minded representation of these two first determinants. This of course has to be seen as a qualitative genetic scheme. The behaviour of each single individual will be in fact determined not only by the genetic traits, but also by the contingent conditions of life, like social environment, upbringing, education, historical framework, religion, etc. We will go on with other possible genetic determinants of being human in Part Two.
Text by Pier Luigi Luisi and Angelo Merante
Continues on the 23rd of February.
Biondi, G., and Rickards, O. (2009). Umani da sei milioni di anni. L’evoluzione della nostra specie. Roma, Carocci.
Capra, F., and Luisi, P. L. (2014). The Systems View of Life. A Unified Vision. Cambridge University Press.
Keller, E. F. (2000). The Century of the Gene. Cambridge, MA: Harvard University Press.
Luisi, P. L. (2016). The Emergence of Life: From Chemical Origins to Synthetic Biology. 2nd Edn., Cambridge University Press.
Noble, D. (2006). The Music of Life. Oxford University Press.
Wilson, D., and Reeder, D. A. (1993). Mammal Species of the World, 2nd edn. Washington, DC: Smithsonian Institute Press.
Wrangham, R., and Peterson, D. (1996). Demonic Males. New York: Houghton Mifflin.