The end of the year is a good time to go introspective and ponder the ultimate question about life, the universe and everything. Where do we come from? What is the origin of life?

Two scientists have moved beyond the dominant assumption that the answer can be found in Darwinian evolutionary theory. They propose to shift the search for the emergence of life from hardware to software. The transition from non-life to life might not have originated in a chemical change in matter, but rather in an upgrade in information processing capabilities.

Paul Davies, an ASU Regents’ Professor and director of the Beyond Center for Fundamental Concepts in Science, and Sara Walker, a NASA post-doctoral fellow at the Beyond Center, published their theory in the article The Algorithmic Origins of Life.

Darwin

The authors don’t reject Darwin’s theory of evolution. ‘The theory gives a convincing explanation of how life has evolved incrementally over billions of years from simple microbes to the richness of the biosphere we observe today’, they write. However, the theory sheds no light on the emergence of life. Darwin himself already pointed that out: ‘It is mere rubbish, thinking at present of the origin of life; one might as well think of the origin of matter’, he wrote in a letter to J.D. Hooker in 1863.

Despite of this, research into origin of life has been predominantly framed by the Darwinian paradigm. Darwin, of course, suggested that life evolves through replication subjected to variation and selection. Mapping that idea onto the origin of life yields the hypothesis that some non-living self-replicating molecules will eventually evolve into a living entities.

Attributing life to a random chemical transition is a decidedly materialistic approach. A focus on the hardware, so to speak. Walker and Davies signal two weaknesses in prioritizing hardware. First, there is an enormous gap between even the most complex chemical reaction networks scientists engineer in laboratories and the simplest biology. The jump from non-life to life seems unbridgeable.

Secondly, the Darwinian evolutionary process does not only apply to living systems. It is equally applicable to software programs, memes and –as stated above- simple molecular replicators. Therefore a purely Darwinian viewpoint does not provide an answer to the question ‘what is life? And ‘without a definition of life, the problem of how life began is not well posed’, the authors write.

Information

The main argument of the authors is that shifting priority from hardware to software does provide a singular definition about what life is. They postulate that life emerges in that instant when information gains control over the matter it is embodied in. I’ll get back to that later.

Since the discovery of DNA, biologists assign an ever-increasing importance to the role information plays in living systems. But the dominant view is that though information is essential to the operation of a system, it isn’t an inherent quality of the system itself. Information is merely a vehicle that lets the hardware components of the system know what to do. It is a passive agent and has no autonomy.

Walker and Davies reject the dominant view and maintain that ‘flow of information’ is not only an inherent quality of a system, it actually defines it. There are two kinds of information flows: bottom-up and top-down. The former is when the information sent out by low-level components determines the operation of the system. In the case of a simple self-replicating molecule the chemical reactions of the subsystems determine the behavior of the molecule.

When information flows top-down the system as a whole exerts causal control over the subsystems. The information –all the relations between the elements in the system- becomes what dictates the operation of that system as a whole.

This can be exemplified by DNA in a living human being: DNA has information on it. Some (but by no means all) of this DNA is read out, this process determines what proteins are expressed. These proteins in turn go back to the DNA and change which DNA is read out by switching different genes on and off. There is feedback between the two subsystems. The proteins base their ‘decision’ to switch certain genes off, on information coming from sources distributed throughout the entire organism.

In this sense, information manipulates its physical substrate. Information becomes a software program that tells the hardware how to replicate.

As I mentioned above, this is what Walker and Davies propose to call life: information taking control over the matter it is instantiated in. In other words, when information flows top down.

The emergence of life, then, is that instant when the flow of information transitions from bottom-up to top-down.

Via: Asunews.asu.edu

Photo: Legomyphoto.wordpress.com