Post on 15-Jun-2020
The meaning of “life”David BaumProfessor University Wisconsin, Madison
Life as we know itLAWKI shares many features
Life as we know itA reflection of common ancestry
Last universal common ancestor
Life in general?Focus on generic features
LIFE
..but which?
A “working definition”
Life is a self-propagating chemical system capable of undergoing adaptive evolution(Modified from Joyce, 1994)
Focus on generic features..but which?
A “working definition”“Self-propagating” includes growth and cellular
reproduction
A “working definition”“Adaptive evolution” entails the potential to
complexify and become more out-of-equilibrium
Fitness/Co
mplex
ity
Time
MutationSelection
Chan
ce o
rigin
of p
roto
cell
Protocell
First cell
Towards modern cells
Chance origin of surface protoplasm
Metabolizingpropagule
Growingpropagule
Dividingpropagule
Adaptive evolution explains how more complex structures can arise over time
Baum (2015)
Origin of life cares about LAWKI and life in general
Self-propagation and evolution are key
MutationSelection
ReferencesBaum D.A. 2015. Selection and the origin of cells.
Bioscience. 65:678-84Joyce, G., 1994. Foreword: In Origins of life: The central
concepts, ed. DW Deamer and GR Fleischaker. Jones and Bartlett, Boston.