Those hefty molars helped us grind up fibrous veggies.

Then, around 1 million to 2 million years ago,

we invented cooking,

which softened food so we didn't need to chew as much.

That put wisdom teeth out of a job.

Around 10,000 years ago,

we began to farm and cook our food even more.

With less work to do, our powerful jaws shrank,

making it harder for those extra teeth

to fit in our mouths.

And today, we suffer the consequences.

Gum infection, tooth decay, even tumors.

But, unfortunately, annoying extra molars

aren't the only way evolution screwed us over.

All primates, including humans, have something in common:

We have incredibly bony feet.

Each one contains 26 bones.

Together, that's almost a quarter

of all the bones in our body.

Now, this foot design makes perfect sense

to our ancient primate ancestors,

because all those tiny moving parts

made their feet flexible enough to cling to branches.

But here's the problem:

Once our ancestors left the trees

and started walking upright,

we needed a more rigid, stable foot to balance

and propel ourselves from one step to the next.

We didn't lose a single bone.

The result? Our feet are too flexible,

and they can easily twist the wrong way,

which leads to all sorts of foot-related ailments,

like sprains, stress fractures, and tendonitis.

If that's not bad enough,

walking upright also messed up our spine.

In animals that walk on all fours,

the spine arches like a bridge,

which helps support the weight

of their internal organs dangling beneath.

Then, 6 million years ago,

our ancestors first stood up

and forced that smooth arch into an S shape.

The top is curved outward to support the weight of our head,

and the bottom is curved inward

to keep our torso in line with our feet,

so we can balance.

Unfortunately, this design isn't very sound.

That bend in our lower back

puts a tremendous amount of pressure on our backbone.

So it's no wonder that 60% to 70% of people worldwide

experience lower-back pain sometime in their life.

Speaking of pain, let's talk about

getting hit in the testicles.

Unlike most of your organs,

they hang outside your body,

so they aren't protected by muscles, fat, and bone,

which makes them a prime target for incoming soccer balls.

So why are we, and many other mammals,

stuck with such a risky arrangement?

Well, it turns out, sperm are healthiest

when they're stored in a cool place.

So we hold them as far away from the body as possible

to keep them a few extra degrees below body temperature.

And humans have it especially bad.

Since we walk upright, gravity pulls

on our exposed testes,

which can lead to a potentially excruciating condition

called inguinal hernia.

And while this might feel like the worst thing ever,

other evolutionary quirks can be deadly.

Take the dangerous way our throat is structured.

It contains two important tubes,

the trachea, or windpipe, where air travels,

and the esophagus, where food travels.

These pipes are nestled so close together,

it's just plain stupid.

Because when you swallow,

food can slip into your windpipe and block airflow,

causing you to choke or suffocate.

Every year, about 5,000 Americans die

by choking on food.

Meanwhile, other animals have a more sensible arrangement,

where their windpipe and esophagus

are far away from each other.

So, why don't we have that setup?

Well, by sticking the pipes together,

we can open up extra space in our throats,

which acts like an echo chamber

to amplify sound to help us talk.

But evolution doesn't always come with a silver lining.

In the 18th century, millions of sailors

suffered from a horrible disease called scurvy.

Their gums would swell and bleed

as their skin disintegrated and their brains decayed.

The culprit?

Away from shore for months on end,

the sailors had no access to fresh fruits and vegetables,

key sources of vitamin C,

which plays a crucial role in how our body

repairs damaged tissue, bone, and nerves.

Now, humans, along with other apes,

guinea pigs, some bats, birds, and fish,

are the only animals that would ever have this problem,

because everyone else can produce their own vitamin C,

no oranges needed.

Meanwhile, humans have a gene mutation

that prevents us from doing the same.

Which normally wouldn't be a problem

for our ancient, fruit-eating ancestors,

who didn't trap themselves on ships

without fresh fruit for months.

Now, there doesn't seem to be any benefit to this mutation,

which just goes to show,

evolution isn't always helpful.

In fact, it can make life a whole lot worse.