Introduction

A genome is the complete set of genetic instructions for an organism. For each of us, it is forty-six large molecules of DNA in the nucleus of every cell, each packaged into its own chromosome, together with many copies of a shorter fragment of DNA that lies in a specific compartment of the cytoplasm.

This genome makes us what we are, by determining, directly or indirectly, the structure of every complex molecule in our body. Together with a little help from the genomes in our parents, and our parents’ parents, it determines how our bodies are put together, and how they function, and how they interact with the myriad environmental influences before and after birth to make us what we are today.

Genomes are by no means the only, or even necessarily the best, level of organization at which to study how all these complex things happen, but they are interesting. In this chapter, I look at some of what we have learnt about life by studying genomes.

Living organisms are extraordinary. They have capabilities which far exceed any present-day technology, and it is therefore inevitable that scientists and engineers should seek to emulate at least some of those capabilities in artificial systems. Such an endeavour not only offers the possibility of practical applications, but it also sheds light on the nature of biological systems.

The notion of artificial life can take many diverse forms, and in this article we will focus on three aspects: modelling the development of structure in living systems, the quest to create artificial intelligence, and the emerging field of synthetic biology. All three topics reveal surprising, and sometimes remarkably deep, connections between the apparently disparate disciplines of biology and computer science. There is something else which links these three strands: the Cambridge mathematician Alan Turing (see Figure 4.1) whose birth centennial we celebrated in 2012.

It is widely acknowledged that Turing laid many of the foundations for the field of computer science, although amongst the general public he is perhaps best known for his role in breaking the Enigma and other cyphers at Bletchley Park during the Second World War (Hodges 1992). What is perhaps less widely appreciated is that Turing also made important contributions to biology. As we shall see, each of the three topics discussed in this paper builds on a different seminal contribution made by Turing.

The boundary between life and non-life has been the guiding principle for this interdisciplinary exploration of the notion of life. The chapters that follow start with cells, bio-electrical mechanisms, evolutionary processes and artificial intelligence. Then, in the social world, they consider work on the boundary of death, the way we have envisaged life in the distant past, the metaphor of ruined life, and how first humanity imagined going beyond life.

Cells are the minuscule bricks of life. Ron Laskey describes how living things are kept alive and healthy by the balancing of life and death among the trillions of cells of which they are made. Different functions require cells to have very different life expectations, from a few days to the whole life of the body. Each cell’s birth and death is wholly altruistic. It is determined by what is needed for the best functioning of the body of which they are so tiny a part. The scale and complexity of what is required to keep a whole organism alive and healthy stretches our imagination. At the heart of every cell’s birth is the process of division and thus replication of its DNA, an act of, in terms of man-made things, incomprehensible precision.