Thanos is, well, not very bright.

Say what you will about Doc Ock,

Syndrome, or Lex Luthor.

At least they put considerable

scientific thought behind their evil plans.

Nanowires feed directly into my cerebellum.

Narrator: Meanwhile, check out Thanos' master plan.

The entire time I knew Thanos,

he only ever had one goal:

to bring balance to the universe

by wiping out half of all life.

Narrator: Yeah, this scheme to conserve resources

by eliminating half of all life makes no sense.

In fact, it wouldn't save the planet.

It would doom it.

Let's start with his decision to wipe out half of humanity.

Now at first, you can see his reasoning.

After all, there are 7.7 billion humans on the planet today.

That's nearly 7% of all the people

who have ever lived in the history of our species,

which makes for a pretty crowded planet.

So if half of us suddenly vanished,

wouldn't that be a worthy sacrifice?

No. Ethics aside, we'd still be left

with almost 3.9 billion people,

about the same world population in 1972.

So if history repeats itself,

it would buy us less than 50 years

before we reached current levels again,

and the same is true for many animal species

like deer, whose healthy populations

would help them rebound quickly.

But unfortunately, the same can't be said

for endangered species who have the opposite problem.

Take the critically endangered Sumatran tiger, for example.

Experts estimate there are fewer

than 400 left on the planet.

If half disappeared, there wouldn't be

enough to sustain the population,

and they would likely go extinct,

and endangered sharks, hawks, and leopards

would probably meet the same fate,

and that's where Thanos' plan to save

the world really falls apart.

Once a top predator disappears,

they can take the rest of their ecosystem down with them.

Take gray wolves for example.

The US government eradicated them

from Yellowstone in the 20th century.

With the wolves gone, the elk population

exploded and devoured the local vegetation,

which disrupted the population of

beavers, birds, and other species

that relied on those plants to survive,

and it gets even worse once you consider

that half of every plant species on Earth is gone too

because just like with animals,

there are thousands of endangered plant species,

many of which are too vulnerable

to survive Thanos' plot,

and if plant species die out,

the rest of their food chain would starve.

Of course, many plant populations aren't endangered,

but even that won't save them all in the long run.

You see, scientists estimate that 90% of all

flowering plants depend on animals to reproduce,

but Thanos wiped out half of all

bees, fruit bats, and every other pollinator on the planet,

many of which are already in trouble.

For example, 50% of bee species in the Midwest

have vanished in the past century,

and the lesser long-nosed bat,

a key pollinator in the Sonoran desert,

is also disappearing,

so they would probably die off completely,

and if enough pollinators go poof,

we're looking at a possible total ecological collapse.

So while Thanos' plan wouldn't

directly devastate thriving species,

the chain reaction that could come

from eliminating endangered species

could really mess things up for everyone else left alive.

No resurrections this time.

Narrator: Nice going, Thanos.

To be fair, the planet has experienced

mass extinctions before, and life recovered.

For example, an asteroid strike 66 million years ago

wiped out 75% of all species on Earth,

and with the dinosaurs out of the way,

our mammalian ancestors flourished.

But even so, experts estimate it takes

around 20 million to 30 million years

to recover from a mass extinction.

So unless waiting around for millennia

was all part of the plan,

the Mad Titan messed up, big time.