marathon

Marathon, Washington DC 2004
Photo: US marines ©GNU free

Bipedal Homo spec. mankind started as long distance walkers and absolutly not as marathon runners in an African open dry ecosystem.
Savannah, that was for years the usual picture in textbooks and defended by almost all anthropologists.
It changed later into to a concept of adaptive walking in deteriorating woodlands and then forced to start on open land ecosystems.

But bipedalism is in the aquatic view a reasonable first adaptation to wading in coastal waters. Wading, diving and swimming to obtain seafood not only as "free" option but obligatory because isolation on as sparse ecosystem rich archiplago.

Trapped on small archipelagos, ancestors of hominoids transformed into bipedal beachcombers, adapted to an in- and out of the water way of life.
The moment when "their" islands were connected to mainland because the sea level lowered, bipedalism was the a next "step" literally.
Walking is then a secondary spin off from this adaptation that became usefull reaching continents.

So the ancestral lineage of able climbers and possible knuckle walkers were in this view forced to adapt in a semi-aquatic habitat.
Changing into bipedal, swimming, singing (and killing) creatures is strongly reflected in our present Homo sapiens versatile nature: climber,
weight lifter, swimmer, diver, runner, fisher, sailor, moon-walker, acrobat, rapist and of course merciless killer....
The semi-aquatic view does not deny that modern man is a specialised walker and runner.

But we know now, that Homo erectus, one of the main ancestor groups for us, were not runners. Their skeleton was not fit for that and it
should learn us to rethink our "bragging" about us being the Olympic winners and of course our ancestral Genus Homo members were at their start the same.

Marathon running as dubious strategy was already shown by the first one in history that gave the name to this kind of contest; Pheidippides.
This Greek runner died at his "finish" in Athens in 490 B.C. after delivering the message of the defeat of Persians at Marathon

backgrounds on Marathon Man

When partaking in long distance running, man has a problem. He loses much water transpiring and at the same time a lot of salt.
Dehydration lurks, but drinking water does not help, on the contrary. In those circumstances our brains take in water by osmosis
Headache and dizziness are the symptoms, mistaken for dehydration.
This can be fatal, see Marathon victim died and backgrounds on Marathon Man 2.

Of course there are human populations that are very able runners.
To learn more about this: the Tarahumaro Indians in the Sierra Nevada of Mexico are interesting talented and they are very popular for US running sporters.

...see Created Runners

Salt for the population

It looks as if man is suffering an unstable salt regime. If food contains enough salt en there is no excess transpiration, there are no problems.
in the (later) period of developing, humans did settle far from coastal regions and food did contain less salt, salt sub population became necessary.
It is not sure, when salt transport to the inland started as a form of bartering trade. But it is clear, that frequently seashells are a part of the remains,in human shelters far form the coast. A connection seems obvious. Sub population of the diet with salt could be as old as mankind itself during his colonizing of the continents. It is known that the oldest cities of Micelles and China did trade salt and used it as currency. We use the same even today as common noun: "Selling", a "salary" for our "soldiers"..

See
http://www.chemheritage.org/educational services/pharm/antibiot/readings/salt.htm

Geologist Richard Cowen's essay on the importance of salt in history
http://en.wikipedia.org/wiki/History_of_salt

As spin off, the invention of the use of salt as a preservative for meat and other foods is easy to imagine. And that seems to be one of the basic starting points for many old civilisations. We know this from China, the Middle east - Jericho was a central trading post for salt -. The same seems to be the case in Central America.
In ancient times, salt (or the lack of it) could drastically affect the health of entire populations.
Trade in salt was very important, and salt was valuable enough to be used as currency in some areas.
The Latin phrase "salarium argentum," "salt money," was part of the payment made to every Roman "soldier", and the word has been carried down the ages into the English word "salary" and "sale".

In this perspective it is rather odd, that generally salt is brandished for many ailments in man. People advocating a "natural" diet, are convinced that a low salt diet is the real thing. This lead to a hype in de USA, around the made up diet of our ancestors: the "Paleolithic Diet". It is related to the view that we originated on salt depleted Savannah's. And that could easily be wrong.

There are outcomes of epidemical studies, indicating that salt depleted diets do not influence high blood pressure and do produce more heart failures than a more salty diet..See backgrounds on Marathon, salty dispute.
An in depth article from Aswers.com gives more details Water Balance . It acknowledges that salt regulation in man is a problem and that loss of water by transpiration can be profound.

Food experts are seriously divided about this as you can find out for yourself on the different sites on food.
If man indeed does have a relative high need for salt in his diet and also a bad feedback system for controlling it which is especially harmful for his brains in dehydrating conditions, than this is an important point, contradicting his savannah origin.