Download 18 April 2007 - Santa Fe Institute

Inevitable Life?
Eric Smith
18 April 2007
• Why is there life on earth at all?
• How and where did it originate?
• Why has life persisted?
• Does the biosphere contain relics of
emergence?
Accidents can matter
“Any replay of the tape
would lead evolution
down a pathway
radically different
from the road
actually taken.”
Against vitalism and animism
“The biosphere does not contain
a predictable class of objects or of
events but constitutes a particular
occurrence, compatible indeed
with first principles, but
not deducible from
those principles and
essentially unpredictable”
A “happy accident”
“the origin of life appears at the moment
to be almost a miracle, so many are the
conditions which
would have had to
have been satisfied
to get it going”
• What were they thinking?
• Is this science or an odd prejudice?
• Is a different story truer to life?
The (family) tree of life
9OUAREHERE
Control and inheritance
What (all) is life?
NH2
OH
O
O
OH
HO
O O O
O
OH
HO
NH
O
OH
O
Bridging chance
and necessity
O
O
OH
HO
NH
O
OH
O O
OH
HO
O
O
.ECESSITY
#HANCE
Universal
Steady
Predictable
Variable
Fluctuating
Contingent
The metabolic
organization of life
2EDUCTIVE
METABOLISMS
!UTOTROPHS
(ETEROTROPHS
/XIDATIVE
METABOLISMS
Ecologies are more
fundamental than individuals
2EDUCTIVE
ECOLOGIES
/XIDATIVE
ECOLOGIES
The major transitions in
evolution were chemical
#OMPLEX#ELLS
-ULTICELLULARITY
%NERGY#APTURE
#ORE-ETABOLISM
/XIDATIVE
2EDUCTIVE
-3.8
-3.5
-2.0
-0.5
Origin(?)
Photosynthesis (?)
Endosymbiosis
Cambrian explosion
The universal core
of biochemistry
Fatty acids
O
OH
HO
O
HO
HO
OH
HO
OH
OH
HO
O
O
O
OH
O
O
O
O
OH
O
O
OH
HO
OH
O
O
O
Amino acids
OH
O
O
OH
OH
Sugars
O
O
O
O
OH
O
O
OH
HO
OH
HO
O
O
O
OH
HO
O
Nucleic acids
Cofactors
O
OH
OH
HO
O
• Why life?
Under stress, Things
break down
Lightning is the atmosphere
breaking down electrically
Hurricanes are atmosphere
breaking down thermally
• The emergence of life: a chemical breakdown?
• Where?
• What was the stress?
The “Heaven” theory of origin
The “Hell” theory:
Hydrothermal vents
White smoker
chimney
Black smoker
The problem solved by life
A free lunch you are
paid to eat
50
formate
$fGo / Carbon
0
oxaloacetate
fumarate
malate
cis-aconitate
isocitrate
citrate
-50
pyruvate
A-ketoglutarate
succinate
methanol
acetate
-100
ethanol
propanol
butanol
pentanol
-150
-200
methane
1
1.5
2
2.5
H2 / CO2 (formation)
3
3.5
4
A chemical Hurricane
O
OH
OH
HO
OH
O
HO
O
O
O
OH
HO
O
O
OH
HO
O
O
OH
HO
OH
O
O
O
OH
O
O
O
O
HO
OH
HO
OH
O
O
O
OH
O
O
OH
OH
OH
HO
O
O
O
OH
O
O
OH
HO
O
OH
HO
O
Take-home thoughts
• Metabolism first!
• Life arose and persists to enable metabolism
• Emergence of life a chemical breakdown
• Biosphere is part of the geosphere