0:00:07.114,0:00:09.163
Nicolas Steno is rarely heard of

0:00:09.163,0:00:11.436
outside Intro to Geology,

0:00:11.436,0:00:14.245
but anyone hoping to understand life on Earth

0:00:14.245,0:00:17.174
should see how Steno expanded and connected

0:00:17.174,0:00:18.675
those very concepts:

0:00:18.675,0:00:21.758
Earth, life, and understanding.

0:00:21.758,0:00:25.226
Born Niels Stensen in 1638 Denmark,

0:00:25.226,0:00:26.813
son of a goldsmith,

0:00:26.813,0:00:28.139
he was a sickly kid

0:00:28.139,0:00:30.642
whose school chums died of plague.

0:00:30.642,0:00:32.559
He survived to cut up corpses

0:00:32.559,0:00:33.726
as an anatomist,

0:00:33.726,0:00:36.357
studying organs shared across species.

0:00:36.357,0:00:38.249
He found a duct in animal skulls

0:00:38.249,0:00:40.227
that sends saliva to the mouth.

0:00:40.227,0:00:41.728
He refuted Descartes' idea

0:00:41.728,0:00:43.862
that only humans had a pineal gland,

0:00:43.862,0:00:46.113
proving it wasn't the seat of the soul,

0:00:46.113,0:00:48.942
arguably, the debut of neuroscience.

0:00:48.942,0:00:51.949
Most remarkable for the time was his method.

0:00:51.949,0:00:54.200
Steno never let ancient texts,

0:00:54.200,0:00:55.708
Aristotelian metaphysics,

0:00:55.708,0:00:57.503
or Cartesian deductions

0:00:57.503,0:01:01.173
overrule empirical, experimental evidence.

0:01:01.173,0:01:05.131
His vision, uncluttered by speculation or rationalization,

0:01:05.131,0:01:06.060
went deep.

0:01:06.060,0:01:07.673
Steno had seen how gallstones

0:01:07.673,0:01:10.426
form in wet organs by accretion.

0:01:10.426,0:01:11.768
They obeyed molding principles

0:01:11.768,0:01:13.556
he knew from the goldsmith trade,

0:01:13.556,0:01:15.155
rules useful across disciplines

0:01:15.155,0:01:16.739
for understanding solids

0:01:16.739,0:01:18.771
by their structural relationships.

0:01:18.771,0:01:20.310
Later, the Grand Duke of Tuscany

0:01:20.310,0:01:21.977
had him dissect a shark.

0:01:21.977,0:01:23.890
Its teeth resembled tongue stones,

0:01:23.890,0:01:26.393
odd rocks seen inside other rocks

0:01:26.393,0:01:28.979
in Malta and the mountains near Florence.

0:01:28.979,0:01:31.203
Pliny the Elder, old Roman naturalist,

0:01:31.203,0:01:33.530
said these fell from the sky.

0:01:33.530,0:01:34.703
In the Dark Ages,

0:01:34.703,0:01:36.493
folks said they were snake tongues,

0:01:36.493,0:01:38.254
petrified by Saint Paul.

0:01:38.254,0:01:41.058
Steno saw that tongue stones were shark teeth

0:01:41.058,0:01:42.393
and vice versa,

0:01:42.393,0:01:45.003
with the same signs of structural growth.

0:01:45.003,0:01:47.757
Figuring similar things are made in similar ways,

0:01:47.757,0:01:49.396
he argued the ancient teeth

0:01:49.396,0:01:50.877
came from ancient sharks

0:01:50.877,0:01:53.679
in waters that formed rock around the teeth

0:01:53.679,0:01:55.420
and became mountains.

0:01:55.420,0:01:58.637
Rock layers were once layers of watery sediment,

0:01:58.637,0:02:00.280
which would lay out horizontally,

0:02:00.280,0:02:01.390
one atop another,

0:02:01.390,0:02:03.197
oldest up to newest.

0:02:03.197,0:02:04.679
If layers were deformed,

0:02:04.679,0:02:05.199
tilted,

0:02:05.199,0:02:07.164
cut by a fault or a canyon,

0:02:07.164,0:02:09.487
that change came after the layer formed.

0:02:09.487,0:02:10.779
Sounds simple today;

0:02:10.779,0:02:12.998
back then, revolutionary.

0:02:12.998,0:02:14.660
He'd invented stratigraphy

0:02:14.660,0:02:17.113
and laid geology's ground work.

0:02:17.744,0:02:21.734
By finding one origin for shark teeth from two eras

0:02:21.734,0:02:24.631
by stating natural laws ruling the present

0:02:24.631,0:02:26.628
also ruled the past,

0:02:26.628,0:02:30.134
Steno planted seeds for uniformitarianism,

0:02:30.134,0:02:33.091
the idea that the past was shaped by processes

0:02:33.091,0:02:34.798
observable today.

0:02:34.798,0:02:36.754
In the 18th and 19th centuries,

0:02:36.754,0:02:39.255
English uniformitarian geologists,

0:02:39.255,0:02:41.468
James Hutton and Charles Lyell,

0:02:41.468,0:02:43.972
studied current, very slow rates

0:02:43.972,0:02:46.014
of erosion and sedimentation

0:02:46.014,0:02:48.190
and realized the Earth had to be way older

0:02:48.190,0:02:51.308
than the biblical guestimate, 6000 years.

0:02:51.308,0:02:53.316
Out of their work came the rock cycle,

0:02:53.316,0:02:55.056
which combined with plate tectonics

0:02:55.056,0:02:56.436
in the mid-twentieth century

0:02:56.436,0:02:58.907
to give us the great molten-crusting, quaking,

0:02:58.907,0:03:01.483
all-encircling theory of the Earth,

0:03:01.483,0:03:05.556
from a gallstone to a 4.5 billion-year-old planet.

0:03:05.556,0:03:06.907
Now think bigger,

0:03:06.907,0:03:08.022
take it to biology.

0:03:08.022,0:03:10.160
Say you see shark teeth in one layer

0:03:10.160,0:03:11.539
and a fossil of an organism

0:03:11.539,0:03:13.188
you've never seen under that.

0:03:13.188,0:03:15.447
The deeper fossil's older, yes?

0:03:15.447,0:03:16.502
You now have evidence

0:03:16.502,0:03:19.707
of the origin and extinction of species over time.

0:03:19.707,0:03:21.171
Get uniformitarian.

0:03:21.171,0:03:23.350
Maybe a process still active today

0:03:23.350,0:03:26.844
caused changes not just in rocks but in life.

0:03:26.844,0:03:28.982
It might also explain similarities and differences

0:03:28.982,0:03:30.421
between species

0:03:30.421,0:03:32.621
found by anatomists like Steno.

0:03:32.621,0:03:33.729
It's a lot to ponder,

0:03:33.729,0:03:36.269
but Charles Darwin had the time

0:03:36.269,0:03:37.902
on a long trip to the Galapagos,

0:03:37.902,0:03:40.467
reading a copy of his friend Charles Lyell's

0:03:40.467,0:03:42.323
"Principles of Geology,"

0:03:42.323,0:03:44.496
which Steno sort of founded.

0:03:44.496,0:03:46.530
Sometimes giants stand on the shoulders

0:03:46.530,0:03:48.529
of curious little people.

0:03:48.529,0:03:50.882
Nicolas Steno helped evolve evolution,

0:03:50.882,0:03:52.431
broke ground for geology,

0:03:52.431,0:03:55.041
and showed how unbiased, empirical observation

0:03:55.041,0:03:56.890
can cut across intellectual borders

0:03:56.890,0:03:58.936
to deepen our perspective.

0:03:58.936,0:04:00.752
His finest accomplishment, though,

0:04:00.752,0:04:01.882
may be his maxim,

0:04:01.882,0:04:03.189
casting the search for truth

0:04:03.189,0:04:05.719
beyond our senses and our current understanding

0:04:05.719,0:04:07.284
as the pursuit of the beauty

0:04:07.284,0:04:09.476
of the as yet unknown.

0:04:09.476,0:04:11.443
Beautiful is what we see,

0:04:11.443,0:04:13.694
more beautiful is what we know,

0:04:13.694,0:04:17.274
most beautiful, by far, is what we don't.