28 Scientiﬁc American, August 2017
the new origins of
were thought to
hold life’s origins.
By Martin J. Van
David W. Deamer
and Tara Djokic
August 2017, ScientiﬁcAmerican.com 29
BIRTHING POOL: Life on Earth
could have started in places similar
to the Grand Prismatic Spring
in Yellowstone National Park.
30 Scientiﬁc American, August 2017
PRECEDING PAGES: WERNER VAN STEEN Getty Images
Heading up the side of the creek embankment,
Djokic suddenly stumbles back downhill. Has she lost
her balance? To stop her from falling, Van Kranendonk
reaches out to stop her and pushes her back uphill,
which prompts a screech, something unintelligible, and
ﬁnally a sputtered cry: “Sp- .. . p- . . . p- . . . pppider!”
Djokic has not stumbled at all. She is in ﬂight mode, in
fear for her life as she tries to swat away the thick spi-
der web enveloping her. Spiders have a deservedly bad
reputation in Australia. In the dark, it is not a good idea
to assume that you have found the odd benignspecies.
The reason we are feeling our way around the Pilba-
ra at night is because we had spent the day enthralled by
a new discovery Djokic had made in 3.48-billion-year-old
sedimentary rocks called the Dresser Formation. Some
of the rocks are wrinkled orange and white layers, called
geyserite, which were created by a volcanic geyser on
Earth’s surface. They revealed bubbles formed when gas
was trapped in a sticky ﬁlm, most likely produced by a
thin layer of bacterialike microorganisms. The surface
rocks and indications of bioﬁlms support a new idea
about one of the oldest mysteries on the planet: how and
where life got started. The evidence pointed to volcanic
hot springs and pools, on land, about 3.5billion years ago.
This is a far dierent picture of life’s origins from
the one scientists have been sketching since 1977. That
was the year the research submarine Alvin discovered
hydrothermal vents at the bottom of the Paciﬁc Ocean
pumping out minerals containing iron and sulfur and
gases such as methane and hydrogen sulﬁde, surround-
ed by primitive bacteria and large worms. It was a
thriving ecosystem. Biologists have since theorized that
such vents, protected from the cataclysms wracking
Earth’s surface about four billion years ago, could have
provided the energy, nutrients and a safe haven for life
to begin. But the theory has problems. The big one is
that the ocean has a lot of water, and in it the needed
molecules might spread out too quickly to interact and
form cell membranes and primitive metabolisms.
Now we and others believe land pools that repeated-
ly dry out and then get wet again could be much better
places. The pools have heat to catalyze reactions, dry
northwestern Australia, guided only by the dim light from a GPS screen. The light is
too weak to reveal fallen trees that ﬁll the dry creek bed we are following, and we keep
tripping over them. We are two geologists working in a remote region of the country
known as the Pilbara: Djokic up front and Van Kranendonk several steps behind. Our
truck, parked somewhere on a small plateau, seems a world away. We are not sure if
the GPS’s batteries will hold out long enough to show us the way back. The night sky,
ablaze with countless stars visible right down to the horizon, twinkles in an amazing spectacle
as Jupiter dances with nearby Venus. Sadly, this spectacle provides little navigational help for
two scientists fumbling their way through the Australian outback in June 2014.
Martin J. Van Kr anendonk is di rector of the Austr alian
Center for A strobiology in t he School of Biologi cal, Earth
and Environ mental Sciences a t the University of New S outh
Wales. He has co nducted researc h for more than 30 years
in extrem ely old rocks acros s the planet.
Tara Djokic is a Ph.D. candi date at the Australia n Center
for Astro biology at the Univer sity of New South Wales .
Her projec t combines geolog ic observations of e arly evidence
of life in Western A ustralia with vir tual-reality tec hnology.
To get started, life on Earth needed energy to cre-
ate complex molecules and ways to bring these
A system of volcanic pools and hot springs on land
has the needed ingredients for life and wet-dry cy-
cles for interaction and natural selection.
A land-based volcanic origins theory, in contr ast to
an ocean-focused one, guides us to dierent places
in the solar s ystem to search for life th ere.
David Deamer is a faculty member in t he department
of biomolec ular engineering at t he University of C alifornia,
Santa C ruz. He is author or ed itor of 12 books, inc luding
The Origins of L ife (2010), co-e dited with Jack W. Szostak , and
First Life (2011), publis hed by the Universit y of California Press .
August 2017, ScientiﬁcAmerican.com 31
COURTESY OF MARTIN J. VAN KRANENDONK
spells in which complex molecules called polymers can
be formed from simpler units, wet spells that ﬂoat
these polymers around, and further drying periods that
maroon them in tiny cavities where they can interact
and even become concentrated in compartments of fat-
ty acids—the prototypes of cellmembranes.
What Djokic found was strong geologic evidence
that the Dresser, now a dry, hot and barren outback en-
vironment, had once been like the steaming pools and
erupting geysers of Yellowstone National Park in the
U.S., an active geothermal ﬁeld. And everywhere in the
Dresser there are fossilized signs of life intimately asso-
ciated with the old hot spring system. Although the
Dresser was not the actual site where the most primi-
tive life began half a billion years earlier, it was show-
ing us that hydrothermal environments on land were
present very early in Earth’s history. Charles Darwin
had suggested, back in 1871, that microbial life origi-
nated in “some warm little pond.” A number of scien-
tists from dierent ﬁelds now think that the author of
On the Origin of Species had intuitively hit on some-
thing important. And the implications of these ideas
stretch beyond our own planet: in our search for alien
life elsewhere in the solar system, a land-based theory
about origins would guide us to dierent places and
planets than would an ocean-based theory.
FROM RUSSIA WITH LIFE
Djokic’s run-in with the spider web,
another of us (Deamer) had shown that volcanic pools
could foster the assembly of compartments made of
membranes, essential boundaries of all cellular life.
Deam er led a group of scientists to Mutnovsky, an ac-
tive volcano in the Kamchatka peninsula of far eastern
Russia. The group was exploring a prebiotic analogue
site, a region that can give researchers a sense of what
the planet was like four billion years ago, before life be-
gan. Deamer’s idea was that simple molecular building
blocks might join into longer information-carrying
polymers like nucleic acids—needed for primitive life
to grow and replicate—when exposed to the wet-dry cy-
cles characteristic of land-based hot springs. Other key
polymers, peptides, might form from amino acids un-
der the same conditions. Crucially, still other building
blocks called lipids might assemble into microscopic
compartments to house and protect the information-
carrying polymers. Life would need all the compounds
to get started, and Mutnovsky had an abundance of hot
springs and geysers in which the idea could betested.
Deamer had brought a bottle of white powder con-
taining raw material that was likely available on the
prebiotic Earth, including four amino acids and four
chemical bases that compose naturally occurring nu-
cleic acids, as well as phosphate, glycerol and a lipid.
He poured this mixture into the center of a small, boil-
ing spring. Within minutes a white, frothy foam
emerged around the spring’s edges. The foam was com-
posed of countless tiny vesicles, each containing com-
pounds that were present in the originalsoup.
If the compartments dried out around the edges of
the puddle, could their contents, already in close prox-
imity, join together as polymers? Could this be a step-
ping-stone to the ﬁrst life? Back in his laboratory, Deam-
er and his colleagues tested the idea by mixing simple
nucleic acids called nucleotides with lipids. The mix-
ture was put through cycles of wetting and drying un-
der the acidic conditions and high temperatures found
in the Kamchatka pool. The result: longer polymers
ranging from 10 to more than 100 nucleotides in length.
Later studies using x-ray diraction demonstrated the
polymers resembled ribonucleic acid, or RNA. Further-
more, these polymers were encapsulated by the lipids
to form vast numbers of microscopic compartments
LIFE ON THE
rocks in Austra-
lia’s Pilbara re -
gion are called
posed of miner-
from geysers in
hot springs (1).
The rocks show
bands rich in
light bands com-
of potassium in
view (one centi-
meter in width)
served in this
were formed in
of bio logical
organ isms (3).
called protocells. Though not alive, they were clearly
an important step towardlife.
Deamer used just a few wet-dry cycles in his experi-
ments and got relatively simple molecules. A colleague
of his at the University of California, Santa Cruz, com-
puter scientist Bruce Damer, suspected that many more
cycles might add another key feature: the survival of
the ﬁttest. Each drying cycle, Damer ﬁgured, would
cause lipid membranes of the vesicles to open, allowing
polymers and nutrients to mix. On rewetting, the lipid
membranes would reencapsulate dierent mixtures of
polymers, each mixture representing a kind of natural
experiment. More complex protocells would have bet-
ter chances of survival because their greater variety of
molecular mixtures might stabilize the protocells in
various conditions—one set of molecules helping in one
set of surroundings, another helping in a dierent set.
These intact protocells would then survive to pass on
these polymer sets to the next generation, climbing an
evolutionary ladder. Damer realized that this model re-
sembled a kind of chemical computer “booting up” the
functions of life, starting with random “programs” writ-
ten in the form of polymers.
In 2015 Damer added a third phase to the two-part
cycle: an intermediate stage between wet and dry.
The idea occurred during a ﬁeld trip with the co-au-
thors to the Dresser Formation in search of stromato-
lites, which are the fossilized layers of bacterial mats
and some of the earliest evidence of life on Earth.
Damer was walking through the desert near a granite
outcrop known as Gallery Hill that is covered with
Aboriginal rock carvings known as petroglyphs.
On the way, he noticed brown, dried-up micro-
bial mats in small depressions in the outcrops.
Out of curiosity, Damer poured water on the
mats, and they sprung back to life, becoming
green and gel-like. He realized that if wet-dry
cycles in an origin pool also included a moist
phase, in which surviving protocells crowd togeth-
er into a similar gel, polymers and nutrient mole-
cules could mix and exchange across the barriers of
lipid membranes. This community of cooperating
protocells would have even more opportunities to ﬁnd
the best molecules for survival. Forty years earlier, in
fact, scientists George Fox and the late Carl Woese
proposed the term “progenote” for such a communal
primordial phase of life; Fox told Damer this matched
his protocell gel.
POOLS OF INNOVATION
composition that Djokic
found in the Dresser Formation made it a likely spot for
the three-part cycle to occur, and we published the ev-
idence this past May in Nature Communications. After
we realized that the Dresser had been ﬁlled with sur-
face hot springs in a geothermal system, it became
clear that it also had contained many of the key ingre-
dients and organizational structures required for the
origin of life. It had a source of energy in the form of
Hot springs, pools and geysers can kick-start chemical systems
necessary for life on Earth to begin, according to one theory.
The conditions set in motion seven steps, beginning with chemical
synthesis, moving through cycles of increasing complexity and
ending in colonization of new territory.
Many of life’s basic
building blocks, such as
amino acids , are formed
in space and fa ll to Earth.
compounds, along with
others generated within
hot springs on a vo lcanic
in hydrothermal pools.
32 Scientiﬁc American, August 2017
August 2017, ScientiﬁcAmerican.com 33
The best-adapted proto-
cells spread t o other
pools or str eams, moving
by wind and wate r, and
some develop the ability
to use carb on dioxide for
photosynthe sis. After
much trial an d error, one
protocell as sembles the
compli cated molecular
machin ery that en ables it
to divide into daughter
cells. This p aves the way
for the rs t livin g micro
Some of these early
microbes are pushed
into saltwater estuaries,
beyond their native
freshwater ponds. The
microbes that survive
pass along useful traits
that help descen dants
expand their range
to oceans .
Sea storm s and tugging
tides sele ct for mats of
rugged microbes able
to cement themselves
together using grains
of minerals. These layers
pile up into st acks called
stromatolites. Life con-
tinues to expand into
other niches, setting the
stage for f ree-living cells.
After bil lions of years,
these organisms evolve
into com plex multicellular
plants and animals.
to fo rm lms .
layers, simpl e
Protocells that survive
the changing conditions
then group to gether in a moi st
gel as the poo l level drops.
When the pool
rells, the lms
bud o trillions
The cycle repeats, again and
again. Ever y time it does,
protocells interact, compete
for re sources and evolve
more complex functional
poly mers until a “proge-
emerges that is able
to exchange adap tive
ing ever more sop his-
Pools go through
repeated c ycles of three
phases: dr y, wet and
moist gels. Dry times
help to synt hesize poly-
mers used to c arry infor-
mation, such as chains
of nucleic aci ds. In a wet
period, protocells can
these poly mers and pro-
tectin g them. Then, in
the gel phas e, protocells
pack toget her in a system
called a pro genote and
exchange set s of poly-
mers, selecting those
that enhance survival
during many cycles.
The compounds are
concentrated within tiny
vesicles made of simple
molecules called lipids.
The close proximity, plus
heat and chemical energy
from the spring system,
links them together
to form more co mplex
Illustration by José Miguel Mayo (landscape) and Jen Christiansen (cycling detail)
34 Scientiﬁc American, August 2017
THEO ALLOFS Getty Images
circulating hydrothermal ﬂuids, rich in hydrogen, heat-
ed by magma from below. The rocks contained abun-
dant amounts of the element boron, a crucial ingredi-
ent in the synthesis of ribose necessary for nucleic ac-
ids such as RNA. The Dresser also has phosphate
minerals that dissolve out of the underlying rocks and
join circulating acidic geothermal ﬂuids. Phosphate is
an important component of nucleic acids, but it is also
used by all life in the form of ATP (adenosine triphos-
phate, the molecule that supplies energy within cells).
In addition, there were high concentrations of zinc and
manganese, components of many enzymes in the cyto-
plasm of cells from all known branches of life, found in
hydrothermal vents and in evaporative volcanic lake
deposits. Finally, the Dresser also had clays, which can
function as catalysts for creating complex organic mol-
ecules because of the electrically charged layers of min-
eral surfaces theycontain.
Perhaps the most exciting thing about the Dresser
as an origin analogue site is its amazing variety be-
cause in this ﬁeld of science, variety is very much the
spice of life. The Dresser is dry and rocky now, but in
their youth, geothermal hot spring ﬁelds such as this
one contain many hundreds of pools, each with a
slightly dierent pH, temperature, dissolved ions and
other chemical variations. Chemical complexity is rich
in such ﬁelds because they contain three highly reac-
tive interfaces—between water and rock, water and air,
and rock and air. The ﬁelds also have dierent temper-
atures at dierent spots. Multiply all of this together:
the wetting-drying cycles happening multiple times
each day (think Old Faithful in Yellowstone), variable
Journey to a Land across Time
When I rst set foot in Western Australia’s Pilbara, a landscape
holding 3.5-billion-year-old clues to the beginning of life, I was
very disappointed. The year was 1994. I drove excitedly out of the
wes t coast tow n of Port Hedla nd , but all I saw for the rs t 15 0 kilo-
meters were a few withered, scraggly trees and smoky dust devils
traipsing across the burnt, at plain. I felt desolated. What had I
gotten myself into? And the heat!! I’d never experienced anything
this brutal before. Or breathed air so thick with biting ies.
But as we continued to head south on the highway to Marble
Bar—the hottest town in Australia—some low, broad hills start-
ed to rise from the horizon. We started to cross sandy creeks
and rivers, including the mighty Shaw, whose banks were gar-
nished with lush-looking coolabah trees, with their distinctive,
As we continued down a dirt track into the hills, the burnt
plains gave way to grass-covered hummocks.
This grass is called spinifex, an amazing but
devilish creation. It grows as bushes up to one
meter in diameter, with round, ne blades that
taper into needle-sharp tips made almost of
pure silica. The tips will penetrate through just
about any piece of fabric . My supervisor
whipped out thick gaiters to protect his legs.
But he had failed to inform me of the hazard.
Without any gaiters, I was a walking porcu-
pine within minutes—my skin skewered with
multiple silica needle tips that broke o and
remained in my esh for months.
The land, ultimately, proved worth the dis-
comfort. Here I was walking over some of
Earth’s oldest, best-preserved rocks that con-
tain evidence of life from almost the very
beginnings of time on our planet. As I looked
at some wrinkly structures that lay above the
ripples of ancient sediment, I realized I was
looking at remnants of our great-, great-,
great-grandparents—the precursors to all complex life on Earth!
This area had changed much from when it was rst formed
3. 5 billion year s ag o. Back then it woul d have be en a black volc a-
nic land, with no color from vegetation. Over the hills I might have
glimpsed a green, iron-rich sea underneath an orange sky heavy
with carbon dioxide and devoid of oxygen. Nearby in the land-
scape I’d come across elds of hot springs, and here I’d start to see
some color. There would be stretches of white and yellow and red
around bubbling mud pools and splashing geysers, the colors of
sulfur, clay and iron. And in some pools and channels, perhaps
there would have been strands of beige, red and purple: colonies
of heat- and chemical-loving microbes. There might even have
been some green from very early photosynthesizing organisms.
If I were able to ride a time machine forward a billion years, I’d
see the Pilbara become buried under kilometers of volcanic lavas
and sediments; I’d see the landmass move
across the face of the globe and run into other
pieces of crust, the collisions forming moun-
tain belts. At about 2.5 billion years ago, I’d
see the oceans ll with life, the shallow coastal
areas occupied by huge reefs made of primi-
tive microbes called cyanobacteria that stack
in piles of mats called stromatolites. The sky
would turn blue as the photosynthesizing cya-
nobacteria sucked in carbon and pumped out
oxygen into the atmosphere. Almost another
two billion years later the world would turn
cold and become covered in a global ice
sheet, wiping out almost every living thing.
When it melted away, oxygen levels rose
again. Life really got going. Animals slowly
colonized the land, as did new types of plants.
The greening of our planet began in earnest,
and a wide variety of organisms appeared—
including, unfortunately for me, spinifex.
— M. J .V. K .
CRADLE OF LIFE? Australia’s
Pilbara region, now dry, once
held hot springs and geysers.
August 2017, ScientiﬁcAmerican.com 35
pool chemistries, highly reactive interfaces, the ability
of pools to exchange compounds as geysers splash their
contents back and forth, and an interconnected, ﬂuid-
ﬁlled, subterranean fracture network. When you do the
math, it looks as if a terrestrial geothermal ﬁeld of 100
springs can generate a million or more new combina-
tions of conditions every year!
Each warm pond becomes an “innovation pool,” a
test bed in which adaptive combinations of molecules
rapidly emerge and ﬁnd ways to grow and reproduce or
in which maladaptive combinations fall by the wayside,
unable to keep up. It is likely that immense numbers of
combinations might have been required to assemble
the ﬁrst primitive version of life, in which case the pro-
cess would take hundreds of millions of years. But the
numbers of combinations in terrestrial geothermal
ﬁelds suggest that life could have originated and begun
to evolve in as little as 10 million years, with the ﬁrst
stages beginning as soon as there was a stable crust
peppered with volcanic landmasses amid the oceans,
just more than four billion yearsago.
that surface hot springs are the
most likely sites of life’s beginnings. The deep-sea vent
hypothesis is still alive and kicking. At
’s Jet Pro-
pulsion Laboratory, biochemist Mike Russell has devel-
oped Alvin’ s original discovery of hydrothermal vents
into an alternative, elegant—but as yet unproven—
model. In his scheme, mineral membranes that form
minuscule pores within vent rocks initially separate al-
kaline water from more acidic ocean water. This pro-
duces a gradient of several pH units, similar to the dif-
ference between a solution of household ammonia and
a glass of orange juice. The gradient is a form of energy
that can be tapped; modern bacterial cells do exactly
this to generate the ATP they need. There is another
source of energy in the vents in the mixture of dis-
solved gases such as hydrogen and carbon dioxide.
Russell and his colleagues have proposed that when
carbon dioxide in ancient seawater mixed with hydro-
gen coming from the vents, the transfer of electrons
from hydrogen to carbon dioxide could synthesize
more complex organic compounds. In their view, the
mineral compartments resemble cells, and the energy
of pH gradients and hydrogen could ultimately evolve
into a primitive metabolism required by the earliest
The hot spring ﬁeld and deep-sea vent hypotheses
have some far-ﬂung implications. Beyond guiding fur-
ther explorations of life’s beginnings on Earth, they
point to dierent ap proaches to search for life on oth-
er planets and their moons. If the deep-sea vent origins
theory is correct, the icy ocean worlds of Enceladus and
Europa may be good places to look. On the other hand,
if our model of ﬂuctuating hot springs is right, then
these worlds are unlikely to hostlife.
What about Mars? Although there is good evidence
for shallow seas on Mars in the distant past, there are
few signs of a global ocean or of tectonic spreading
zones that create hydrothermal vents on Earth. If life
depended on vents to begin, it was unlikely to have be-
gun on the Red Planet. But if life on Earth originated in
terrestrial hot springs, it could have also begun on
Mars, which had the hot spring ingredients of wide-
spread volcanism and water. Indeed, in 2008 the Spir-
it rover discovered 3.65-billion-year-old hot spring de-
posits in the Columbia Hills on Mars, about the same
age as our Dresser hot springs, which did a great job of
preserving early evidence for life on Earth.
Both the deep-sea vent and the land-based hot spring
pools models have a long way to go before either can be
deemed correct. The origin of life is like a jigsaw puzzle
with many dierent pieces, and we do not know enough
yet to put each one in the proper position. At the Dress-
er Formation, for instance, we do not understand what
causes certain elements to become concentrated in dif-
ferent pools, how geothermal ﬁelds evolve over time, or
how their dierent chemistries interact to synthesize or
degrade organic molecules. We need to construct more
sophisticated experiments of prebiotic chemistry in a se-
ries of warm little pools, studying how complex organic
molecules form and how they interact and combine
when encapsulated within membranes.
Both on land and in the sea, chemical and physical
laws have provided a very useful frame around this par-
ticular puzzle, and the geologic and chemical discover-
ies described here ﬁll in dierent areas. But before we
can see a clear picture of the origin of life, many more
pieces need to be put in place. What is exciting, however,
is that now we can see a path forward to thesolution.
MORE TO E XPLORE
A Nonhyper thermophil ic Common Ances tor to Extant L ife Forms. Nicolas Galtier et al.
in Science, Vol. 28 3, pages 2 20–221; Janua ry 8, 1999.
The Onset a nd Early Evolutio n of Life. Michael J. Ru ssell and Allan J. H all in Geological Society
of America Memoirs, Vol. 198, pag es 1–32; 200 6.
Geologi cal Setting of E arth’s Oldest Fo ssils in the ca. 3. 5 Ga Dresser Fo rmation, Pilbar a
Craton, Wes tern Australia . Mar tin J. Van Kranen donk et al. in Precambrian Research, Vol. 167,
Nos. 1–2, page s 93–124; November 10 , 2008.
First Lif e: Discovering the C onnection s between Stars , Cells, and How Li fe Began. David
Deamer. Unive rsity of Cali fornia Press, 2 011.
Molecular and Cellular Fossils of a Mat-like Microbial Community in Geothermal Boratic Sin-
ters. Wriddhiman Ghosh et al . in Geomicrobiology Journal, Vol. 29, No. 10, p ages 879–88 5; 2012.
Origin of Fi rst Cells at Terrest rial, Anoxic Ge othermal Field s. Ar men Y. Mulkidjanian et a l.
in Proceeding s of the National Aca demy of Sciences U SA, Vol. 109, No. 14, page s E821–E83 0;
April 3, 2 012.
Ester-Me diated Amide Bon d Formation Drive n by Wet-Dry Cycles: A Possibl e Path to Poly-
peptides o n the Prebiotic E arth. Jay G. Fors ythe in Angewandte Chemie International Edition,
Vol. 54 , No. 34, pages 9 871–9875; Augus t 17, 2015.
Hydrother mal Conditions a nd the Origin of Ce llular Life. David W. Deame r and Christos D.
Georgiou in Astrobiology, Vol. 15, No. 1 2, pages 109 1–1095; Decemb er 2015.
A Field Trip to the A rchaean in Searc h of Darwin’s Warm Littl e Pond. B ruce Damer in Life,
Vol. 6, No. 2, A rticle No. 2 1; June 2016.
Earlies t Signs of Life on La nd Preserved i n ca. 3.5 Ga Hot S pring Deposit s. Tara Djok ic et al.
in Nature Communications, Vol. 8, A rticle No. 152 63; May 9, 2017.
FROM OUR A RCHIV ES
Origin of Li fe on Earth. Alons o Ricardo and Jac k W. Szostak; Septem ber 2009.