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SUMMARY:Topological scaling laws and the non-equilibrium statistical mecha
 nics of evolution - Nigel Goldenfeld (University of California\, San Diego
 )
DTSTART:20230703T153000Z
DTEND:20230703T160000Z
UID:TALK201100@talks.cam.ac.uk
DESCRIPTION:For the last 3.8 billion years\, the large-scale structure of 
 evolution has followed a pattern of speciation that can be described by br
 anching trees. Recent work\, especially on bacterial sequences\, has estab
 lished that despite their apparent complexity\, these so-called phylogenet
 ic or evolutionary trees exhibit two unexplained broad structural features
  which are consistent across evolutionary time. The first is that phylogen
 etic trees exhibit scale-invariant topology\, which quantifies the fact th
 at their branching lies in between the two extreme cases of balanced binar
 y trees and maximally unbalanced ones. The second is that the backbones of
  phylogenetic trees exhibit bursts of diversification on all timescales. I
  present a coarse-grained statistical mechanics model of ecological niche 
 construction coupled to a simple model of speciation\, and use renormaliza
 tion group arguments to show that the statistical scaling properties of th
 e resultant phylogenetic trees recapitulate both the scale-invariant topol
 ogy and the bursty pattern of diversification in time. These results show 
 in principle how dynamical scaling laws of phylogenetic trees on long time
 -scales may emerge from generic aspects of the interplay between ecologica
 l and evolutionary processes\, leading to scale interference.\n&nbsp\;\nFi
 nally\, I will argue that these sorts of simplistic\, minimal arguments mi
 ght have a place in understanding other large-scale aspects of evolutionar
 y biology. In particular I will mention two questions where we do not have
  even a qualitative understanding let alone a quantitative one: (1) the sp
 ontaneous emergence of the open-ended growth of complexity\; (2) the respo
 nse of evolving systems to perturbations and the implications for their co
 ntrol. Even though biology is intimidatingly complex\, "everything has an 
 exception"\, and there are a huge number of undetermined parameters\, stat
 istical physics reasoning may lead to useful new insights into the existen
 ce and universal characteristics of living systems.\n&nbsp\;\nWork perform
 ed in collaboration with Chi Xue and Zhiru Liu and supported by NASA throu
 gh co-operative agreement NNA13AA91A through the NASA Astrobiology Institu
 te for Universal Biology
LOCATION:Seminar Room 1\, Newton Institute
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