0:00:07.129,0:00:13.469
In 1845, Ireland's vast potato fields[br]were struck by an invasive fungal disease

0:00:13.469,0:00:17.278
that rapidly infested this staple crop.

0:00:17.278,0:00:19.261
The effect was devestating.

0:00:19.261,0:00:21.619
One million people died of famine,

0:00:21.619,0:00:25.830
and over a million more were forced[br]to leave Ireland.

0:00:25.830,0:00:31.871
Nowadays, we avoid such agricultural[br]catastrophes with the help of pesticides.

0:00:31.871,0:00:35.640
Those are a range of manmade chemicals[br]that control insects,

0:00:35.640,0:00:37.219
unwanted weeds,

0:00:37.219,0:00:38.300
funguses,

0:00:38.300,0:00:39.072
rodents,

0:00:39.072,0:00:40.200
and bacteria[br]

0:00:40.200,0:00:42.270
that may threaten our food supply.

0:00:42.270,0:00:44.749
They've become an essential part[br]of our food system.

0:00:44.749,0:00:49.090
As populations have grown,[br]monoculture, single crop farming,

0:00:49.090,0:00:51.710
has helped us feed people efficiently.

0:00:51.710,0:00:57.036
But it's also left our food[br]vulnerable to extensive attack by pests.

0:00:57.036,0:01:00.671
In turn, we've become more dependent[br]on pesticides.

0:01:00.671,0:01:06.500
Today, we annually shower over 5 billion[br]pounds of pesticides across the Earth

0:01:06.500,0:01:09.195
to control these unwanted visitors.

0:01:09.195,0:01:12.071
The battle against pests,[br]especially insects,

0:01:12.071,0:01:15.031
has marked agriculture's long history.

0:01:15.031,0:01:16.911
Records from thousands of years ago

0:01:16.911,0:01:21.354
suggest that humans actively burned[br]some of their crops after harvest

0:01:21.354,0:01:23.805
to rid them of pests.

0:01:23.805,0:01:29.122
There's even evidence from ancient times[br]that we recruited other insects to help.

0:01:29.122,0:01:34.621
In 300 A.D., Chinese farmers specially[br]bred ferocious predatory ants

0:01:34.621,0:01:39.296
in orange orchards[br]to protect the trees from other bugs.

0:01:39.296,0:01:41.172
Later, as large-scale farming spread,

0:01:41.172,0:01:47.131
we began sprinkling arsenic, lead,[br]and copper treatments on crops.

0:01:47.131,0:01:51.010
But these were incredibly toxic[br]to humans as well.

0:01:51.010,0:01:54.371
As our demand for more, [br]safer produce increased,

0:01:54.371,0:01:56.982
so did the need for effective chemicals

0:01:56.982,0:02:00.223
that could control pests[br]on a grander scale.

0:02:00.223,0:02:04.633
This ushered in the era [br]of chemical pesticides.

0:02:04.633,0:02:08.902
In 1948, a Swiss chemist named[br]Paul Hermann Müller

0:02:08.902,0:02:12.001
was awarded a Nobel Prize [br]for his discovery

0:02:12.001,0:02:18.442
of dichlorodiphenyltrichloroethane,[br]also known as DDT.

0:02:18.442,0:02:23.262
This new molecule had unparalleled power[br]to control many insect species

0:02:23.262,0:02:28.213
until the 1950s,[br]when insects became resistant to it.

0:02:28.213,0:02:33.552
Worse, the chemical actually drove[br]dramatic declines in bird populations,

0:02:33.552,0:02:35.373
poisoned water sources,

0:02:35.373,0:02:40.572
and was eventually found to cause[br]long-term health problems in humans.

0:02:40.572,0:02:44.993
By 1972, DDT had been banned[br]in the United States,

0:02:44.993,0:02:48.943
and yet traces still linger[br]in the environment today.

0:02:48.943,0:02:52.453
Since then, chemists have been searching[br]for alternatives.

0:02:52.453,0:02:56.494
With each new wave of inventions,[br]they've encountered the same obstacle -

0:02:56.494,0:02:58.744
rapid species evolution.

0:02:58.744,0:03:01.334
As pesticides destroy pest populations,

0:03:01.334,0:03:05.723
they leave behind [br]only the most resistant individuals.

0:03:05.723,0:03:08.824
They then pass on their [br]pesticide-resisting genes

0:03:08.824,0:03:10.638
to the next generation.

0:03:10.638,0:03:13.193
That's lead to the rise of super bugs,

0:03:13.193,0:03:15.614
such as the Colorado potato beetle,

0:03:15.614,0:03:19.385
which is resistant to over [br]50 different insecticides.

0:03:19.385,0:03:23.834
Another downside is that other bugs[br]get caught in the crossfire.

0:03:23.834,0:03:29.454
Some of these are helpful predators[br]of plant pests or vital pollinators,

0:03:29.454,0:03:34.304
so erasing them from agriculture[br]wipes out their benefits, too.

0:03:34.304,0:03:36.345
Pesticides have improved over time

0:03:36.345,0:03:39.323
and are currently regulated by strict[br]safety standards,

0:03:39.323,0:03:42.905
but they still have the potential[br]to pollute soil and water,

0:03:42.905,0:03:44.314
impact wildlife,

0:03:44.314,0:03:46.185
and even harm us.

0:03:46.185,0:03:50.735
So considering all these risks,[br]why do we continue using pesticides?

0:03:50.735,0:03:52.145
Although they're imperfect,

0:03:52.145,0:03:57.165
they currently may be our best bet[br]against major agricultural disasters,

0:03:57.165,0:03:59.956
not to mention mosquito-born diseases.

0:03:59.956,0:04:04.836
Today, scientists are on a quest for[br]alternative pest control strategies

0:04:04.836,0:04:06.976
that balance the demands[br]of food production

0:04:06.976,0:04:09.395
with environmental concerns.

0:04:09.395,0:04:12.835
Nature has become a major source[br]of inspiration,

0:04:12.835,0:04:17.125
from natural plant and fungal chemicals[br]that can repel or attract insects,

0:04:17.125,0:04:20.925
to recruiting other insects [br]as crop bodyguards.

0:04:20.925,0:04:24.876
We're also turning to high-tech solutions,[br]like drones.

0:04:24.876,0:04:26.926
Programmed to fly over crops,

0:04:26.926,0:04:29.757
these machines can use [br]their sensors and GPS

0:04:29.757,0:04:32.446
to carry out more targeted sprays

0:04:32.446,0:04:36.297
that limit a pesticide's wider [br]environmental impact.

0:04:36.297,0:04:38.826
With a combination [br]of biological understanding,

0:04:38.826,0:04:40.456
environmental awareness,

0:04:40.456,0:04:42.376
and improved technologies,

0:04:42.376,0:04:46.627
we have a better chance of finding[br]a holistic solution to pests.

0:04:46.627,0:04:50.617
Chemical pesticides may never shake[br]their controversial reputation,

0:04:50.617,0:04:51.957
but with their help,

0:04:51.957,0:04:54.857
we can ensure that [br]agricultural catastrophes

0:04:54.857,0:04:56.918
stay firmly in our past.