The Genetic Symphony
Nathaniel Centre Staff
Issue 10, August 2003
"The return of Ludwig! 'A Further Feast of Beethoven' was again highly successful in Auckland, Wellington, Christchurch and Dunedin. Of the many letters and emails received there was one from a young newcomer to symphony concerts that summed up the power of the music: "I was full of cold and nearly didn't go, but I'm glad I made the effort – it was just great. Wilma was fantastic (Romances). Saturday night was great as well. I have to say the best piece was Symphony No 9. It was absolutely stunning. I can't believe he was deaf when he wrote it. Unbelievable! I can't say enough about it. I was spellbound. When I looked at the programme and saw it was 67 minutes long I thought 'oh, my goodness'. But the time just flew by. I had tears in my eyes during the third movement. And the drums in the second movement were fantastic. I was still talking to myself about the night long after I got home. Incredible..." [1]
What makes us human?
One of the surprises to emerge from the Human Genome Project was the number of genes humans have – a mere 30,000. That may sound a lot, but when compared with the number in simpler organisms such as fruit flies (13,000) and mustard weed (26,000) it somehow doesn't seem enough. How can the complexity of the human person be produced by 30,000 genes, when a weed has only 4,000 less?
We are undeniably more complex than the yeast in our bread and the weeds in our gardens, and presumably that should be reflected in some way in our genetic makeup. There is another measure that can be used to compare our genome with that of other organisms. Genes are made up of DNA. A DNA molecule is like a ladder, with the sides of the ladder composed of sugar and phosphate molecules, and the rungs formed by units called base pairs. Counting the base pairs in an organism is another way of measuring the size of its genome. So perhaps we can explain our human complexity by considering how many base pairs we have in our DNA?
The human genome contains approximately 3 billion base pairs, the kind of number that might more adequately reflect who we are. But frogs have a similar number of base pairs, and our 3 billion does not come close to that of a single-celled micro-organism called Amoeba dubia which has a genome 200 times larger than ours. As far as genomes are concerned, the amount of DNA an organism has is not a reliable indicator of complexity, nor is the number of genes. These factors are not the determinants of our humanness.
If numbers of genes and amount of DNA do not explain our uniqueness, then what about the nature of our genes? Surely there must be something that makes them human genes?
"Chimpanzees are so closely related to humans that they should properly be considered as members of the human family, according to new genetic research. Scientists from the Wayne State University, School of Medicine, Detroit, US, examined key genes in humans and several ape species and found our "life code" to be 99.4% the same as chimps...other researchers last year put the similarity at around 95%; the figure you get depends on precisely which differences you look at." [2]
In December 2002 the draft of the mouse genetic code was published in the scientific journal Nature. The published code shows that about 80% of genes in mice and humans are the same. The similarity rises to 99% if classes of genes are considered rather than individual genes as, for example, mice have more genes involved in reproduction and smell than we do.
We also share many genes with more humble organisms - about half with the fruit-fly and the nematode worm, and about a fifth with yeast. Scientists have also identified more than 200 genes in the human genome that can be traced to bacteria.
The mystery deepens. How can human uniqueness be explained by a genome in which so many genes are shared with other species?
The Human Symphony
The 90 members of the New Zealand Symphony Orchestra play 22 different instruments, all of which have a range of musical notes. This article begins with a letter from a spellbound concertgoer. On the night in question Beethoven's intricate score enabled the players to re-create his Ninth Symphony. Instruments came into and left the piece, re-entered and then were silent. Some instruments played for most of the symphony, others played for shorter times.
In the programme of concerts the 90 players and their instruments brought not only Beethoven's Ninth Symphony to life, but also works by Dvorak, Tchaikovsky, and Brahms. Each time the same players and the same instruments worked together, each time following a score or pattern that produced a unique piece of music.
If we were to try comparing Beethoven's Ninth Symphony with Dvorak's First Symphony by counting the number of instruments, or the types of instruments, we would not be able to distinguish between the two pieces. Both would have the same components, the 90 players and 22 different types of instruments of the NZSO. The uniqueness of each of the two symphonies lies in the intricate multi-dimensional pattern in which the instruments are played. That intricate and unique pattern is contained in the musical score for each work, and it determines when and for how long each instrument plays, and what it does while it plays.
So it is with our genes. Genes produce proteins, the building blocks of our bodies. In a chimpanzee and a person the same genes create two different beings, not because the genes are different, but because genes are switched on and off in different patterns. Individual genes can also produce more than one type of protein, just as an instrument can produce different notes. This intricate multi-dimensional interaction of the genes controls the development of an organism. The head of a chimpanzee is a different shape to that of a human because the genes involved are switched on for different lengths of time – the jaws of a chimp grow for longer than those of a human at a similar stage of development, and the cranium grows for a shorter time. Each type of organism has its own unique genetic pattern which guides development, not just in the early stages, but throughout life.
When the genomes of organisms of different levels of complexity are compared – for example, single cells, plants, worms, chimpanzees, humans - we find that with increasing complexity, relatively few new genes are added to the genome. The genes that are added are those that control other genes, rather than genes which have new functions. This changes the way in which genes are used, so that as the pattern of interaction and use becomes increasingly complex, a more complex organism results.
As a result we cannot claim exclusive ownership of much of our DNA and genes. The terms 'human gene' and 'human DNA' are in this sense misleading. They imply a uniqueness and ownership of genes that are in fact predominantly the same as those found in other mammals, and to varying degrees in other forms of life. If we have any genes that could be described as particularly our own, they are the small group of genes which determine how other genes are turned on and off at different stages of development and in various parts of the body.
Perhaps the term 'human genes', used so casually in public discussion, has led us into a cul-de-sac. In focusing on the genes we thought were unique to ourselves, we may have begun to subtly and imperceptibly attribute our humanness to DNA molecules. Perhaps we are in danger of confusing the whole with the parts, of reducing the symphony to the instruments. By themselves, these genes do not appear to be the answer to our ultimate question - what makes us human?
Our Relational Nature
"The experience of love, properly understood, remains a simple and universal gateway through which everyone can pass in order to gain an awareness of what makes a person a human being: reason, affection and freedom." [3]
In the 1950s Professor of Philosophy Karol Wojtyla was writing about the human person, about a "rational and free concrete being, capable of all those activities that reason and freedom alone make possible." Nearly 50 years later, the words of Karol Wojtyla, now better known as Pope John Paul II, identify love as the gateway to understanding our humanness. The wisdom of his decades of reflection is revealed in his straightforward assertion that everyone can become aware of what makes us human. Such knowledge is not the preserve of philosophers, theologians and other academics. It can be accessed by anyone who reflects upon and seeks to "properly understand" their own experience of love.
At the heart of this approach is the relational nature of the human person. Our capacity for relationship with God, with self, and with others through love and self-giving is the very essence of our human nature. This three-way relationship draws on and integrates all the attributes that we identify with humanness: conscience and moral judgement, freedom and responsibility, reason and free will, our openness to the transcendent, and our ability to ask questions about what is ultimately important. We have a concept of ourselves – we know ourselves as persons and as members of a family and other groupings – and we know that others also have such a self-concept. We have the ability to make decisions that favour the good of other persons rather than our own self-interest, and to form social structures of a complexity not found among animals. We know that we will die, and this anticipation of death affects how we act and how we live. At the physical level, the tool that most distinguishes us is language, and in particular, symbolic language which allows us to represent general ideas and abstract concepts.
Human infants are born with capacities for self-consciousness, rational thought, and language – characteristics that are part of what makes us human. But what about those few infants who are born without some of these capacities? Of course these children are human. In fact their lives alert us to a gap in our analysis. The attributes to which Pope John Paul II refers enable us to "gain an awareness" of what makes us human. He assumes the presence of the most basic attribute that makes us human, so obvious that it does not have to be stated. Humanness depends first and foremost on our lineage, because we are born into a network of past, present and future human relationships. And if we accept that most basic point, then we have returned again to the issue of our genes.
We may share most of our genes with other species. But those genes, together with the few we can call our own, interact with one another and with the environment in many layers of complexity. The unique pattern of that genetic complexity links us to our forebears and to the rest of the human species, rather than to any other species.
Humanness is not attached to each individual gene but to the complex pattern in which our genes interact with one another and with the environment. Separated from the orchestra, and without the musical score, the violin is not the symphony. It could be part of any ensemble, and could potentially participate in creating many different musical works. There is a parallel with individual genes.
'Human' Genes in Other Organisms
The de-mystification of our genes by science has raised questions about their humanness. It has also raised questions about their use.
"Scientists have for the first time successfully inserted human genes into a pair of lambs, endowing them with the DNA to assist burns victims. The two transgenic lambs, named Cupid and Diana, entered the world armed with a human gene which gives them the ability to produce human serum albumin, a protein that is often used in surgeries and is essential in the treatment of burns victims. If all goes well the lambs' mammary glands will produce milk with the serum, which can be extracted and used to create drugs for humans". [4]
Genes determine what proteins are made in an organism. For scientists searching for useful applications of our burgeoning genetic knowledge, genes are often simply the means to make a particular protein. Twenty years ago a gene copied from the human genome was inserted into bacteria, resulting in a new and efficient way of producing human insulin, a protein of great significance to diabetics. The technology has advanced to the point where new genes can be inserted into the genome of many different living things – plants, animals, bacteria. The inserted gene is coupled with a promoter, which switches it on in a particular part of the organism (for example, the mammary glands) allowing easy access to the protein that results.
Using genes in this way has exciting possibilities. At the same time it creates unease and even fear. In the media the inserted genes are often described as 'human genes'. In fact, these genes are not a stretch of DNA removed directly from a human cell, as the term 'human genes' implies. They code for proteins found in humans, but they may be copies or synthetic genes constructed by scientists in the laboratory. Because more than one combination of DNA bases can code for the same component of a protein, a synthetic gene coding for a human protein does not even have to be identical to the gene in our cells producing the same protein.
Recognising that synthetic genes are being used would be fairer to scientists who work in this field. For those willing to understand the processes involved, it might allay some of the emotions that the words 'human gene' and 'mixing animal and human genes' conjure up. (Of course, using synthetic genes to produce human and other proteins in animals and plants does not address issues for the other organism involved. This topic would need another equally long article to address.)
The technology itself is not unethical. Producing proteins that assist people with cystic fibrosis or burns has an obvious human benefit, and such research has an ethical purpose. Given the benefits it could bring to those with various medical conditions, it would be unwise to rule out use of the technology for this purpose, particularly if we do so on the grounds that the genes being used are 'human'.
At the same time there are valid reasons to be concerned about some uses to which this technology might be put. Inserting DNA into animals such as chimpanzees to see if we can make them more like ourselves raises huge ethical questions. Why would we want to do this? Curiosity? To create a new species of semi-human servants? What is the real purpose and endpoint of such research? Research that involves using inserted DNA to produce human proteins in other organisms needs to undergo ethical scrutiny of its purpose, which pre-supposes that we have identified what purposes are acceptable.
We also need to recognise that not all our genes are the same as those in other organisms. The master regulatory genes which control human development before birth and throughout life should be treated with great caution. Perhaps the use of these genes in other organisms should be outside the limits of what is acceptable.
The emergence of our genes from the shadows has been accompanied by very mixed emotions. We can be excited about their potential for helping us, and many people are. At the same time there is a sense of wariness, a feeling that the best regulatory system in the world might not prevent these scientific advances from somehow endangering our understanding of ourselves.
As we learn to live in the light of a new understanding of our genes, the greatest danger we face may not be related to the technology itself. We expected our 'human genes' to be unique and special and different, but considered individually they are not. There are different responses to this knowledge. Some people fight to avoid any de-sanctifying of our genes, closing off possibilities for their use as a way of retaining belief in their sacredness. Others speak about our genes as mere molecules, complex polymers akin to plastics, with the implication that our human nature can be attributed to the blind operation of physical laws. The gene as sacred component and the gene as chemical structure can both be burdened with too much responsibility for all that makes us human.
Good regulatory systems with their focus on safety in the use of individual genes do not safeguard us from these deeper dangers that have the capacity to subtly affect our self-knowledge. Every human being has an innate sense of human dignity. It is not always easily articulated, but we intuitively know when some action offends against our dignity or that of others. Are we afraid that in inserting genes that produce human proteins to work for us, we will degrade or diminish our dignity?
Again, we must not confuse the violin with the symphony. Human dignity is an attribute of the whole person not of the parts. If we let go of ideas about individual genes as 'human genes' and embrace instead the totality of our humanness, then like the young new-comer to the orchestra we will look upon ourselves with awe, and say Stunning! Fantastic! Incredible!
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[1] From the website of the New Zealand Symphony Orchestra: www.nzso.co.nz
[2] Black R. Chimps Genetically Close to Humans, BBC News Online, 20 May 2003
[3] Pope John Paul II. Special Audience for members of the John Paul II Institute for Studies on Marriage and the Family, 31 May 2001.
[4] Arent L. Lambs get Human Genes, Wired News 22 July 1999.
©
2003