Darwin for all Seasons Eörs Szathmáry Collegium Budapest and Eötvös University

Units of evolution Some hereditary traits affect survival and/or fertility 1.multiplication 2.heredity 3.variability

Some majoir transitions are particularly difficult to explain The origin of evolvability in chemistry The origin of the genetic code The origin of language

The formose ‘reaction’ formaldehyd e glycolaldehyde autocatalysi s Butlerow, 1861

Von Kiedrowski’s replicator

SPREAD for replication (von Kiedrowski)

Classification of replicators Limited heredity Unlimited heredity Holisticformose ModularVon Kiedrowski genes Limited(# of individuals)  (# of types) Unlimited(# of individuals) << (# of types)

The main problem of the origin of life is metabolite channelling Enzymes speed up reactions relative to the unwanted reactions Spontaneous decay reactions abound Maintenance, not only reproduction, requires autocatalysis dx/ dt = k x – d x = 0

Chemical evolution was a race between tar formation and life formation Chemical networks Life Tar What fraction of planets would end up with just tar? What was the role of evolution by natural selection?

Gánti’s chemoton model ALL THREE SUBSYSTEMS ARE AUTOCATALYTIC template copying metabolism membrane growth

Evolution of metabolism: primitive heterotrophy with pathway innovation ABCDABCD Necessarily heterotrophic protocell A B C D ABCABC A B C D Evolved enzymatic reaction Assume D is the most complex

Technology I: evolved nanobots In vitro selection of ribozymes is an excellent example Artifical minimal cells for science and technology More artificial constructs (e.g. out of DNA) Successful copying of connectivity information „The first successful examples of nanobots will be probably similar to some early systems in biology” (Whitesides)

Design features of language Compositionality (meaning dependent on how parts are combined) Recursion (phrases within phrases) Symbolicism (versus icons and indices) Cultural transmission (rather than genetic) SYMBOLIC REFERENCE and SYNTAX

Three interwoven processes Note the different time-scales involved Cultural transmission: language transmits itself as well as other things A novel inheritance system

A simple experiment (Hauser & Fitch) Finite state grammar (AB) n is recognizable by tamarins Phrase structure grammar A n B n is NOT. Human students recognize both: HOW?

Recuerdos de mi vida (Cajal, 1917, pp. 345–350) “At that time, the generally accepted idea that the differences between the brain of [non-human] mammals (cat, dog, monkey, etc.) and that of man are only quantitative, seemed to me unlikely and even a little offensive to human dignity... but do not articulate language, the capability of abstraction, the ability to create concepts, and, finally, the art of inventing ingenious instruments... seem to indicate (even admitting fundamental structural correspondences with the animals) the existence of original resources, of something qualitatively new which justifies the psychological nobility of Homo sapiens?... ’’.

Evolution of the cortex

Ontogenesis of a neuronal network Neurogenesis AND synaptogenesis Implementing projections (lock and key)

Variation and selection in neural development (Changeux) There is vast overproduction of neurons and synapses Transient redundancy is selectively eliminated according to functional needs

Evolution in the brain: some open questions The example of the immune system clearlly shows that launching a within-organism variation- selection mechanism can be adaptive There is de novo production of neurons over the lifespan Multiple rounds of survival selection on neurons generated at different times What exactly could be the units of selection (synapses, neurons, groups, activity patterns)? What about the ‘millisecond meme’?

Between linguistic input and output…

Transmission dynamics in simulated agents

Technology II: evolved, communicating agenst Communication among autonomous agents would be very important (rescue operations, planetary exploration) Artificial evolution of nervous systems (evolutionary robotics) The importance of embodiment: autonomous grounding of emergent semantics