Session F51: Invited Session: Smart Assemblies: Self-Replication, Computation and Error-Free Self-Assembled Systems

The Evolutionary Path Towards Sentient Robots

For over fifty years, engineers have attempted to achieve machine intelligence that rivals human performance, but with only limited success in some specialized arenas such as chess. I will discuss what I believe is the central reason behind this failure, and how using the biological process of evolution can overcome that problem. I show that evolved brains that can learn can be transplanted onto physical robots, who then learn about our world by interacting with it. Such robots do not present a threat to humans, as their brains develop at the same speed as people's, and begin their life as naive as an infant.   

Simple self-replicators: growth via self-assembly and fissioning via bursting bubbles

We explore the principles of and experimentally demonstrate an autonomous and natural scheme for molecular self-replication. The talk will discuss a design for a simple DNA self-replicator that in principle exhibits exponential population growth, is limited by resource consumption, and has the potential to exhibit complicated population dynamics such as competition between species for a common food source. The replicating species are DNA nanotubes made from single-stranded tiles. Our proposed model for self-replication is designed around two basic principles that are ubiquitous on the Earth, and indeed on any oceanic world with crashing waves: growth via molecular self-assembly and fragmentation via violent hydrodynamic flows in bursting bubbles. The talk will focus on recent work to carefully characterise and understand both of these principles. In particular, on the nucleation and growth properties of various kinds, or species, of single-stranded tile nanotubes, and on the capability of bursting bubbles to break these micron-length structures. The proposed experimental system is conceptually very simple, completely autonomous, has the potential for information-based evolution, exploits energy from the environment to release replicated structures, and uses physically plausible mechanisms that could be implicated in the origin of life. \\[4pt] The is joint work with collaborators Erik Winfree, Bernard Yurke, Joy Hui and Rizal Hariadi.   

Self-Replication, Exponential Growth, Selection and Competition in Artificial Systems

Self-replication and evolution under selective pressure are inherent phenomena in life, but few artificial systems exhibit these phenomena. We have designed a process and a system of DNA origami tiles that exponentially replicate a seed pattern, doubling the copies in each diurnal-like cycle of temperature and UV illumination, producing more than 7 million copies in 24 cycles. We use this system to demonstrate exponential selection: two similarly-growing sub-populations, one with a ``red'' dye incorporated, the other with a ``green'' dye, can be controlled by colored light. The light heats one species reducing its replication rate. The progeny of the non-absorbing species replicate preferentially and take over the system. The species selection is enhanced by competition for a resource, critical crosslinking strands required for replication. This addressable selectivity of different constituents in the same solution should be adaptable to the selection and evolution of multi-component nanoscopic-microscopic self-replicating materials. Materials that multiply exponentially and can be selected for specific properties may provide a new paradigm for design from the nanoscopic to the microscopic. Further such systems can provide insights into diverse problems ranging from the origin of life to information, computation and materials science.