0:00:06.700,0:00:13.931
Death and taxes are famously inevitable,[br]but what about decomposition?

0:00:13.931,0:00:16.559
As anyone who's seen a mummy knows,

0:00:16.559,0:00:21.863
ancient Egyptians went to a lot of trouble[br]to evade decomposition.

0:00:21.863,0:00:26.042
So, how successful were they?

0:00:26.042,0:00:28.897
Living cells constantly renew themselves.

0:00:28.897,0:00:32.271
Specialized enzymes [br]decompose old structures,

0:00:32.271,0:00:35.612
and the raw materials [br]are used to build new ones.

0:00:35.612,0:00:38.730
But what happens when someone dies?

0:00:38.730,0:00:41.591
Their dead cells are no longer[br]able to renew themselves,

0:00:41.591,0:00:45.179
but the enzymes [br]keep breaking everything down.

0:00:45.179,0:00:47.795
So anyone looking to preserve a body

0:00:47.795,0:00:52.225
needed to get ahead of those enzymes[br]before the tissues began to rot.

0:00:52.225,0:00:54.301
Neurons die quickly,

0:00:54.301,0:00:57.996
so brains were a lost cause[br]to Ancient Egyptian mummifiers,

0:00:57.996,0:01:01.601
which is why, according [br]to Greek historian Herodotus,

0:01:01.601,0:01:06.053
they started the process[br]by hammering a spike into the skull,

0:01:06.053,0:01:09.146
mashing up the brain, [br]flushing it out the nose

0:01:09.146,0:01:14.954
and pouring tree resins into the skull[br]to prevent further decomposition.

0:01:14.954,0:01:21.122
Brains may decay first,[br]but decaying guts are much worse.

0:01:21.122,0:01:26.648
The liver, stomach and intestines[br]contain digestive enzymes and bacteria,

0:01:26.648,0:01:32.089
which, upon death, start eating[br]the corpse from the inside.

0:01:32.089,0:01:36.675
So the priests removed the lungs[br]and abdominal organs first.

0:01:36.675,0:01:39.762
It was difficult to remove the lungs[br]without damaging the heart,

0:01:39.762,0:01:43.258
but because the heart was believed[br]to be the seat of the soul,

0:01:43.258,0:01:45.608
they treated it with special care.

0:01:45.608,0:01:47.819
They placed the visceral organs in jars

0:01:47.819,0:01:51.159
filled with a naturally occurring salt[br]called natron.

0:01:51.159,0:01:56.840
Like any salt, natron can prevent decay [br]by killing bacteria

0:01:56.840,0:02:01.251
and preventing the body's natural[br]digestive enzymes from working.

0:02:01.251,0:02:04.783
But natron isn't just any salt.

0:02:04.783,0:02:07.991
It's mainly a mixture [br]of two alkaline salts,

0:02:07.991,0:02:11.013
soda ash and baking soda.

0:02:11.013,0:02:14.814
Alkaline salts are especially[br]deadly to bacteria.

0:02:14.814,0:02:19.490
And they can turn fatty membranes[br]into a hard, soapy substance,

0:02:19.490,0:02:22.839
thereby maintaining [br]the corpse's structure.

0:02:22.839,0:02:25.201
After dealing with the internal organs,

0:02:25.201,0:02:29.279
the priest stuffed the body cavity[br]with sacks of more natron

0:02:29.279,0:02:32.696
and washed it clean to disinfect the skin.

0:02:32.696,0:02:37.569
Then, the corpse was set in a bed[br]of still more natron

0:02:37.569,0:02:42.515
for about 35 days [br]to preserve its outer flesh.

0:02:42.515,0:02:44.412
By the time of its removal,

0:02:44.412,0:02:47.589
the alkaline salts [br]had sucked the fluid from the body

0:02:47.589,0:02:50.549
and formed hard brown clumps.

0:02:50.549,0:02:52.661
The corpse wasn't putrid,

0:02:52.661,0:02:56.389
but it didn't exactly smell good, either.

0:02:56.389,0:02:59.865
So, priests poured tree resin over[br]the body to seal it,

0:02:59.865,0:03:04.329
massaged it with a waxy mixture[br]that included cedar oil,

0:03:04.329,0:03:06.987
and then wrapped it in linen.

0:03:06.987,0:03:10.715
Finally, they placed the mummy[br]in a series of nested coffins

0:03:10.715,0:03:14.907
and sometimes even a stone sarcophagus.

0:03:14.907,0:03:19.685
So how successful were [br]the ancient Egyptians at evading decay?

0:03:19.685,0:03:24.853
On one hand, mummies are definitely not[br]intact human bodies.

0:03:24.853,0:03:28.826
Their brains have been mashed up[br]and flushed out,

0:03:28.826,0:03:32.876
their organs have been removed[br]and salted like salami,

0:03:32.876,0:03:37.371
and about half of their remaining[br]body mass has been drained away.

0:03:37.371,0:03:41.974
Still, what remains [br]is amazingly well-preserved.

0:03:41.974,0:03:43.768
Even after thousands of years,

0:03:43.768,0:03:46.344
scientists can perform autopsies [br]on mummies

0:03:46.344,0:03:48.685
to determine their causes of death,

0:03:48.685,0:03:52.635
and possibly even isolate DNA samples.

0:03:52.635,0:03:55.458
This has given us new information.

0:03:55.458,0:04:01.370
For example, it seems that air pollution[br]was a serious problem in ancient Egypt,

0:04:01.370,0:04:05.714
probably because of indoor fires [br]used to bake bread.

0:04:05.714,0:04:11.691
Cardiovascular disease was also common,[br]as was tuberculosis.

0:04:11.691,0:04:16.302
So ancient Egyptians were somewhat[br]successful at evading decay.

0:04:16.302,0:04:21.206
Still, like death, taxes are inevitable.

0:04:21.206,0:04:26.575
When some mummies were transported,[br]they were taxed as salted fish.