
Portolan Charts 'Too Accurate' to Be Medieval - r0muald
http://bigthink.com/strange-maps/648-portolan-charts-too-accurate-to-be-medieval
======
simonh
We know that astronomers and architects in the ancient and medieval world were
capable of formidable feats of measurement and geometric design. The existence
of the Antikythera mechanism despite no known contemporary written accounts of
such mechanisms or their uses shown just how many very large holes there are
in our understanding on the state of the art in ancient world science and
technology in this area. Even Eratosthenes map of the Mefiteranean and Black
Sea from circa 194 BC are easily recognisable and contain all the main
geographic features and rough proportions. Even the map of Britain is a half
decent approximation for someone in Alexandria.

Navigators must have had access to all the same instruments and mathematical
knowledge, and had a very considerable interest in using them effectively. The
results would also have been a vital competitive advantage. As the linked
article says, these charts were considered state secrets.

But obviously, it must have been alien Atlantans from Mars. Or something.

~~~
huxley
> The existence of the Antikythera mechanism despite no known contemporary
> written accounts of such mechanisms or their uses

Actually there are a few written accounts of mechanisms similar to the
Antikythera, probably best known are Cicero's accounts which describe two
devices: one by his teacher Posidonios, which Cicero is believed to have seen
(so roughly contemporaneous), and another created by Archimedes, which most
likely he hadn't.

~~~
simonh
Interesting, I'd not heard that before. I'll look those up, thanks.

------
ZanyProgrammer
I think that people constantly devalue the achievements and accomplishments of
the ancients (in this case, not ancients literally, but medieval people), and
feel like they need to resort to lost civilizations or geniuses in the Elysian
past. Especially with the Middle Ages-no one wants to admit that they were
capable of engineering or scientific achievements.

~~~
matthewbauer
Human intelligence has remained approximately the same for 50,000 years. The
ancient world had its geniuses at the same rate as the modern world. The main
difference is whether their environments enabled them to prosper. Europe
really had some issues in the post Rome era that meant that most of that
talent was not appreciated and lots of knowledge was lost. It sounds like this
stuff came from even earlier and had been passed down without knowledge of how
they were produced.

~~~
cfcef
> Human intelligence has remained approximately the same for 50,000 years. The
> ancient world had its geniuses at the same rate as the modern world.

No, they didn't. Human genetic intelligence may be the same (although this is
doubtful because as ancient genomes slowly become available for analysis, we
see ever more signs of huge numbers of frequencies changing in soft selection
sweeps when we go back only a few thousand years in Europe, so 50k years...?),
but the environments are not nearly the same. The ancient world was absolutely
grindingly dirt-poor compared to the modern world, and the negative
environmental accordingly huge. (Even things like sanitation may not have made
a difference: [http://www.theatlantic.com/health/archive/2016/01/ancient-
ro...](http://www.theatlantic.com/health/archive/2016/01/ancient-roman-
toilets-gross/423072/?single_page=true) )

The most comparable places to the ancient world right now would be somewhere
like subsaharan Africa, where between the subsistence agriculture, parasites,
poverty, and whatnot, despite the benefits of widespread literacy and
vaccines, the average IQ is still quite low, somewhere around IQ 80, or at
least 1 standard deviation below the West; with genius at a cutoff of IQ 140
or so, that implies a rate of geniuses much less than 1/8th the Western rate.

So no, the rate isn't going to be nearly the same. I would note that it's
probably not an accident that when we think of geniuses of antiquity, we tend
to think of people drawn from the urban elite of the capital city of empires
at their peak (eg Athens, Rome)...

~~~
nkoren
Ancient Athens, at its peak, had a total population of less than 300,000
people. They represented the urban elite of an empire of a few million people
at best. I think it would be difficult to find any comparably-sized
contemporary population with a remotely similar genius per capita ratio.

~~~
cfcef
They probably also benefited from low-hanging fruit. No one today has the
opportunity to invent 'logic' or 'the Pythagorean theorem' or 'the tragedy'.

------
jacobolus
Unfortunately, the dissertation under discussion here isn’t actually available
for reading.
[http://dspace.library.uu.nl/handle/1874/291367](http://dspace.library.uu.nl/handle/1874/291367)
“Full Text: Embargo until March 01 2018”

There’s been a lot of theorizing about the Portolan charts (cf. this
bibliography
[http://www.maphistory.info/portolanref.html](http://www.maphistory.info/portolanref.html)).
Claims that they use a Mercator projection per se seem dubious to me.

See this set of presentation slides by Waldo Tobler for a fun view, which the
recent analysis in the linked article purports to debunk,
[http://www.geog.ucsb.edu/~tobler/presentations/Portolani.pdf](http://www.geog.ucsb.edu/~tobler/presentations/Portolani.pdf)

------
lifeisstillgood
tl;dr maps From 13th Century Europe are scarily accurate, use Mercator style
projection and have no obvious antecedents

The level of sophistication of science in medieval Europe may be way ahead of
what we assume (have we even tried to measure it?).

Cartography may well have been leap frogged by one forgotten expedition but
things like the Antekythera mechanism keep pointing to unsung genius and
strong civilisation that we just assume did not exist - what if we were judged
not by Feynmann but by Trump in 1000 years time?

~~~
privong
> Cartography may well have been leap frogged by one forgotten expedition but
> things like the Antekythera mechanism keep pointing to unsung genius and
> strong civilisation that we just assume did not exist - what if we were
> judged not by Feynmann but by Trump in 1000 years time?

I agree with your first point, that we seem to be missing a lot of information
and that early civilizations may have been more advanced than we suspect, in
some ways. But I've re-read the second part a few times and I still don't know
what you're getting at (beyond trying to make an "amirite?" political
comment). Being judged by "Trump" means they would think we incredibly
advanced because "Trump is stupid and would think we're amazing" or that we'd
be judged as stupid because "Trump is stupid and wouldn't see what we had"?
Likewise being judged by "Feynman" would cause us to be viewed as stupid
because he's so smart or us as smart because he'd figured out how smart we
are? Your point might be more effective if you termed it more concretely,
instead of trying to relate it via two figures who exist in different spheres
of human endeavours.

~~~
diziet
The parent was trying refer to 'judged by the achievements of' X.

------
emmelaich
The Mercator _style_ projection is interesting.

My rank speculation is that the originals were drawn during the Roman empire
on spheres and then taken off to form the mosaic.

------
es0m
Fixed link to Uni Utrecht press release: [http://www.uu.nl/en/news/origin-of-
medieval-sea-charts-dispr...](http://www.uu.nl/en/news/origin-of-medieval-sea-
charts-disproven)

Open access version of one of the student's recent articles:
[http://dspace.library.uu.nl/bitstream/handle/1874/327279/Nic...](http://dspace.library.uu.nl/bitstream/handle/1874/327279/Nicolai.pdf?sequence=1)

The thesis is not public as he's written a book on this:
[http://www.brill.com/products/book/enigma-origin-portolan-
ch...](http://www.brill.com/products/book/enigma-origin-portolan-
charts?page=4)

~~~
jacobolus
Thanks for the link. I find most of the analysis logically dubious (in
particular, there’s no mention of astronomy, the author seems to me to have
limited imagination about possible methods for constructing charts over the
course of decades or centuries of work in a field considered an important
economic advantage, and the statistical analysis begs the question more than a
little bit), and the conclusion “13th century Italians weren’t sophisticated
enough to do this, and I don’t know any prior group who _was_ sophisticated
enough, but it must have been the Byzantines or Ancient Greeks or something,
who knows” is entirely unconvincing. Calling this paper a “proof” of anything
is a rhetorical stretch.

But at least we’re now dealing with something more concrete than a press
release.

