Ancient Roman emperors were known for some bizarre  behaviors.

Caligula apparently appointed his horse   as a priest and Nero would cover himself  in wild animal skins, run into an arena and   brutally mutilate people.

Claudius was known  for his clumsy walk, sudden fits of rage and   bursting into uncontrollable laughter.

Most  historians think these stories are exaggerated   gossip spread by political rivals, but even if  they're just 10% true, something was going on.

Could have been a bunch of things, stroke, tumor,  maybe a traumatic brain injury, but it also could   have been caused by eating a lot of lead.

So  did lead lead to the fall of the Roman empire?

Ancient Rome was really into lead.

Lead  is super malleable and corrosion resistant   so it was used in tons of stuff.

Dishes  and utensils contained lead.

Pipe,   transporting water were made of  lead.

Even coffins had lead in them.

Because it was in so much stuff, lead also made  its way into food and drink.

And Roman rulers and   aristocrats were notorious gluttons.

A cookbook  from back then called The Roman Apicius Cookbook,   has about 450 recipes and lead is in almost a  hundred of them in the form of lead acetate, often   called sugar of lead.

When I read that, my first  question was “You guys ever heard a sugarcane?”   Turns out sugar cane wasn't big back then.

So  the options to sweeten something were honey,   which there also wasn't a lot of or grapes,  which they had plenty of.

They boiled down   grape juice to concentrate the sugars, but then  they found that if they boiled it in lead pots,   the syrup would become even sweeter.

What was  happening was that the acetate from the grapes   was combining with lead ions that were leaching  out of the pot to form lead acetate and lead   acetate is sweet.

So it was used in a bunch of  different foods and wine.

And apparently Roman   aristocrats were drinking somewhere between  one and five liters of wine per day.

That's   a lot of inadvertent lead consumption.

One story  goes that the politician Lucullus served around   4 million liters of wine for just one of  his banquets.

I apologize for nothing.

Why were they so okay with drinking and eating  that much lead?

Well, they had no idea it was   toxic.

Lead serves zero purpose in our bodies.

Lead's bad for all of our organs, but what we   often hear about is how much it damages our  brains.

Lead is able to substitute for calcium.

And that's usually why it's so toxic.

Your brain  needs calcium to send messages between neurons and   lead competing with calcium can cause two major  things.

One-- the calcium that should be getting   into your neurons and triggering that message  isn't or two--neurons that aren't supposed to   active start randomly sending messages.

Too much  or too little signaling in your brain can cause a   bunch of behavioral changes.

Think Claudia’s  erratic mood swings, or it can cause issues   processing information, which might make you think  appointing a horse to be a priest is a good idea.

Today we still use lead in some stuff like car  batteries.

But compared to the amount of lead that   the Roman empire used 2000 years ago, or even the  amount of lead that we used a hundred years ago,   we're using very little.

But it is still  in our environment and the stuff that was   made before people realized how toxic it  was, like water pipes in Flint, Michigan.

Corroded pipes leached lead into the  water, making a lot of people very sick.

Okay.

Back to ancient Rome.

Was all the led  that they were eating and drinking enough   to take down an empire?

People have been trying to  figure that out for a while.

Throughout the 1900s,   researchers recreated some of those syrups  that were commonly used in foods and wine,   and they found lead concentrations  of 240 milligrams to one gram   per liter.

That's around 60 times more than what  the EPA allows in public drinking water.

And that   was enough to convince a lot of people that lead  played a big role in ancient Rome's downfall.

But the research didn't stop there.

In 2014, a  team dredged for sediment in the waters around   Rome and compared the amount of lead in that  sediment to the amount preserved in ancient   Rome's pipes.

They figured out that the water  in ancient Rome probably had way more lead in it   than today's tap water, but not enough to be that  harmful or be a major culprit in Rome's demise.

So we know there was at least a good amount  of lead in ancient Rome's water and the syrup   they use to sweeten stuff.

But how much  of that lead was getting into people?

You need to study skeletons to answer that.

Most  Roman empire rulers like Claudius were cremated   so their skeletons aren't around anymore.

But since the 1970s archeologists have been   studying the skeletons of Roman commoners to find  some answers.

In 2019, a team compared skeletons   from the Roman empire to skeletons from the Iron  Age, before lead was popular.

Skeletons from the   iron age contained 0.3 to 2.9 micrograms of lead  per gram.

Whereas the ones from the Roman empire   had from 8 to 123 micrograms per gram.

That's  up to 400 times more lead, absolutely enough   to be messing with brain chemistry.

But does it  mean that it caused the Roman empire to implode?

Can't say for sure.

What we do know  is that human created lead pollution   was a serious problem 2000 years ago.

And  unfortunately it's still causing problems today.