Why is rice so popular? - Carolyn Beans
If you were to place all the rice consumed
each year on one side of a scale,
and every person in the world
on the other,
the scale would tip heavily
towards rice's favor.
This beloved crop contributes over 20% of
the calories consumed by humans each year.
Korean bibimbap, Nigerian jollof,
Indian biryani, Spanish paella,
and countless other culinary masterpieces
all begin with rice.
So how did this humble grain
end up in so many cuisines?
The roots of rice go back thousands
of years to when early farmers
in Asia, Africa, and South America
each independently domesticated the crop.
First came Asian rice,
which many plant geneticists believe
originated in what's now China.
Over 10,000 years ago,
nomadic hunters in the region
began gathering and eating seeds
from a weedy grass.
Then, around 9,000 years ago,
they started planting these seeds,
prompting nomadic hunters to settle
into farming communities.
With each harvest, growers selected
and replanted seeds
from the rice plants
that pleased them most—
like those with bigger and more plentiful
grains or aromatic flavors.
Over millennia, thousands of varieties
of Asian rice emerged.
A relative of the same weedy grass
was also domesticated in Africa
around 3,000 years ago.
Today, its growth is mostly limited
to West Africa.
South American growers also domesticated
rice around 4,000 years ago,
though the crop was lost
after the arrival of Europeans.
Asian rice, however, spread widely,
and is now a cornerstone of diet
and culture in Asia and beyond.
In India and Nepal, many Hindus mark
an infant's transition to solid foods
with a ceremony known as Annaprashan,
where the baby tastes rice
for the first time.
in Japan, rice is so central to diets
that the word "gohan"
means both "cooked rice" and "meal."
The global expansion of rice cultivation
was only possible
because the plant can grow
in many climates—
from tropical to temperate.
As a semi-aquatic plant, rice happily
grows in submerged soils.
Many other crops can't survive
in standing water
because their root cells rely on air
within soil to access oxygen.
But rice plants have air channels
in their roots that allow oxygen to travel
from the leaves and stems
to the submerged tissues.
Traditionally, growers plant
rice in paddy fields—
flat land submerged under as much
as 10 centimeters of water
throughout the growing season.
This practice returns high yields
since many competing weeds
can't hack it in the aquatic environment.
But the technique is also water intensive.
Rice covers 11% of global cropland,
but uses over a third
of the world's irrigation water.
This form of rice production
also pumps out
a surprising amount
of greenhouse gas emissions.
Flooded fields are the perfect breeding
grounds for microorganisms
known as methanogens.
These microscopic lifeforms thrive
in environments lacking oxygen,
because they evolved when the Earth
contained little of this gas.
Methanogens are the only organisms
known to produce methane—
a greenhouse gas 25 times more potent
than carbon dioxide
at trapping heat in the atmosphere.
Cows, for example, are infamous
for burping out methane
due to methanogens in their stomachs.
In a flooded paddy field, methanogens set
to work eating away at organic material
in the submerged soil
and multiplying rapidly,
all the while releasing copious amounts
of methane.
The result: rice cultivation
contributes around 12%
of human-caused methane
emissions each year.
But there's good news.
Rice doesn't actually need to grow
in continuously flooded paddies.
Researchers and growers are exploring
water management strategies
that can cut the methane
while keeping the yield.
One promising technique is known
as alternate wetting and drying.
Growers periodically let
the water level drop,
which keeps methanogen growth in check.
Alternate wetting and drying
can cut water use by 30%
and methane emissions
by 30 to 70% without impacting yield.
Greenhouse gases come from many—
sometimes unexpected— places.
Making rice growing more sustainable
is just one of the many challenges
we'll need to face
to avoid catastrophic warming.
Today, many rice growers still
flood fields all season long.
Changing millennia-old practices
requires a major mindset shift.
But going against the grain could be
just what we need
to keep our planet healthy
and our bowls full.
