THENEWYORKER,DECEMBER13, 2021 31
the school stood out—a plant enthu-
siast who took her students on frequent
field trips. Inspired, Long decided to
study agricultural botany at the Uni-
versity of Reading. Midway to his de-
gree, he took a year off to work for a
British food company, Tate & Lyle,
which owned sugarcane plantations in
the Caribbean and did a lot of sugar
refining. Some at the company thought
it might be possible to dispense with
the plantations and even the cane and
coax plant cells to produce sugar in vats.
The idea didn’t pan out—“It never be-
came economically feasible,” Long told
me when, in July, I went to visit him
at his office—but it got him interested
in the mechanics of photosynthesis.
Photosynthesis takes place within a
plant’s chloroplasts—tiny organelles
that are the descendants of that origi-
nal captured cyanobacterium. When a
photon is absorbed by a chloroplast, it
initiates a cascade of reactions that con-
vert light into chemical energy. These
reactions are mediated by proteins,
which are encoded by genes. Through
a second series of reactions, the chem-
ical energy is used to build carbohy-
drates. This requires more proteins.
Photosynthesis has been called “one of
the most complex of all biological pro-
cesses,” and when Long was starting
out a great deal was still unknown about
how, exactly, it worked. Gradually, using
new molecular tools, researchers suc-
ceeded in filling in the gaps. Photo-
synthesis, they learned, requires the
completion of some hundred and fifty
discrete steps and involves roughly that
number of genes.
The more that was discovered about
the intricacies of photosynthesis, the
more was revealed about its inefficiency.
The comparison is often made to pho-
tovoltaic cells. Those on the market
today convert about twenty per cent of
the sunlight that strikes them into elec-
tricity, and, in labs, researchers have
achieved rates of almost fifty per cent.
Plants convert only about one per cent
of the sunlight that hits them into
growth. In the case of crop plants, on
average only about half of one per cent
of the light is converted into energy that
people can use. The contrast isn’t really
fair to biology, since plants construct
themselves, whereas P.V. cells have to
be manufactured with energy from an-
other source. Plants also store their own
energy, while P.V. cells require separate
batteries for that. Still, researchers who
have tried to make apples-to-apples (or
silicon-to-carbon) calculations have con-
cluded that plants come out the losers.
Long went on to get a Ph.D., and
then took a teaching job at the Univer-
sity of Essex, on England’s east coast.
He became convinced that photosyn-
thesis’s inefficiency presented an oppor-
tunity. If the process could be stream-
lined, plants that had spent millennia
just chugging along could become cham-
pions. For agriculture, the implications
were profound. Potentially, new crop
varieties could be created that could
produce more with less.
“All of our food, directly or indirectly,
comes from the process of photosyn-
thesis,” Long told me. “And we know
that even our very best crops are only
achieving a fraction of photosynthesis’s
theoretical efficiency. So, if we can work
out how to improve photosynthesis, we
can boost yields. We won’t have to go
on destroying yet more land for crops—
we can try to produce more on the land
we’re already using.”
Other biologists were skeptical.
Surely, they observed, if there were a
way to improve photosynthesis that was
truly viable, and not just theoretical,
then, at some point during the past sev-
eral hundred million years, plants would
have hit upon it. What their argument
missed, Long thought, were the exigen-
cies of evolution itself. To be preserved,
biological systems don’t have to be op-
timized. They just have to be functional.
“Evolution is not really about be-
ing productive,” Long told me. “It’s
about getting your genes into the next
generation.”I
n 1999, Long decided that he would
create his own version of photosyn-
thesis. By this time, he’d moved to the
University of Illinois, where many of
the major discoveries about the process
had been made. Long’s idea was to build
a computer simulation that would model
each of the hundred and fifty-odd steps
in photosynthesis as a differential equa-
tion. The effort dragged on for years, in
part because Long’s program kept crash-
ing. Eventually, he got in touch with a
computer scientist who worked for NASA
on rocket engines.“He said, ‘Oh, I had exactly the same
problem, and this is the routine I used,’”
Long recalled. “And we worked with
him and used that routine, and, bingo,
it worked.” Because photosynthesis is
so complicated, and because the math
involved is also complicated, Long’s
model requires a phenomenal amount
of computing power. To simulate the
performance of a single leaf over the
course of a few minutes, it must make
millions of calculations.
Once his model, which he dubbed
e-photosynthesis, was up and running,
Long could create new leaves without
the bother of actually growing any-
thing. He could probe the weaknesses
of photosynthesis and test possible fixes.
What would happen, for example, if a
certain gene were ginned up to pro-
duce more of a certain enzyme? Would
this accelerate photosynthesis or just
gum up the works? The model would
analyze the results of each virtual in-
tervention, or hack. “Of course, ninety-
nine times out of a hundred you’re mak-
ing things worse,” Long said.
It was the hundredth hack that kept
things interesting. Long found that, by
rejiggering certain steps, nature could
be improved upon. In 2006, he pub-
lished a paper outlining half a dozen
“opportunities for increasing photosyn-
thesis.” Among the people intrigued by
the idea were some high-level staff
members at the Bill and Melinda Gates
Foundation. In 2011, the foundation in-
vited Long and some of his colleagues
to Seattle to discuss their work. Six
months later, the foundation invited the
group back. Long and his collaborators
spent a week on Bainbridge Island, in
Puget Sound, drawing up a funding
proposal, and on the last day of their
stay they presented their pitch to Bill
Gates. In 2012, the foundation awarded
them twenty-five million dollars, and
RIPE was created. Later, the project re-
ceived additional funding from Brit-
ain’s Foreign, Commonwealth, and De-
velopment Office and from the Foun-
dation for Food and Agriculture, a joint
public-private venture based in Wash-
ington, D.C.
“It will take multiple innovations to
solve the global food crisis,” Gates told
me via e-mail. These include seed va-
rieties that can better withstand drought,
crops that can better fight off disease,