posted 28 July 2004 03:15 PM            

Date: 1996
Institution: California State University
Advisor: Alan Almquist
Degree: M.A.

Abstract: For decades, archeologists have been aware of evidence
suggesting that the Sahara Desert was much wetter and greener
thousands of years ago. It is now possible to characterize these
locations, in terms of both aquatic and terrestrial biota, but by also
providing some data on the human inhabitants of these ecotomes. This
thesis focused primarily on the features of human settlement in the
central Sahara, looking at lifestyles of the people and examining
factors favoring a wetlands economy. Finally, as the once-favorable
conditions began disappearing, analysis of the destiny of these
Saharan peoples is made.

The Holocene followed the last glacial age, about 12,000 BC. The
temperatures in the Sahara became appreciably warmer and the climate
demonstrated a lower evapotranspiration rate. The Intertropical
Convergence Zone (ITCZ), the line along which north and south weather
fronts converge, seems to have moved several hundred miles to the
north. Since, in general, African rainfall north of the equator
increases as one heads south, the shift of the ICTZ resulted in
Saharan and sahelian zones receiving increased rainfall.

In addition to more temperate plant and animal species moving into the
Sahara, the increased moisture resulted in lakes and rivers filling
far beyond their prior capacity. In some cases, rivers breached their
normal watershed, connecting with other systems. This allowed a
broader distribution of aquatic species. In some areas, there were
widespread wetlands. The earliest such sites, when associated with
human habitation, date from ~7000 BC (with harpoons) and 6000 BC
(wavy-line pottery). Because they used pottery, these cultures were
originally considered some kind of Aquatic Neolithic.

JEG Sutton, in a 1974 article, called them the "Aquatic Civilization
of Middle Africa". Although they did little stonework, he saw their
bone work as very sophisticated. He suspected that much of their
material culture, made of perishable materials, would not have
survived. He thought them "victims" of stone-oriented scholars. Based
on geographic distribution. he thought that the ancestors of Saharan,
Songhai and Chari-Nile-speakers were these same "Middle Africans".

After the initial Holocene (postglacial) wet phase (12,000-7000 BC),
conditions became drier for 500-1000 years. This was fol- lowed by a
lesser wet phase of 2000 years. From then until 2500 BC, there was a
gradual increase in dryness. After that time, weather conditions have
been largely unchanged until the present. How did the human economies
change with the climate?

The early harpoon-fishers availed themselves of large riverine and
lake species, such as the Nile perch (known to exceed six feet).
Whether they were fully-settled or did some amount of yearly travel
isn't known. Undoubtedly, as water-tables dropped, the people needed
to augment their aquatic diet with other foods. Initially, these would
be available plant and animal foods which could be gathered.

Christopher Ehret's work touched on Sutton's language hypothesis--that
these early fishers were NiloSaharan speakers. In the process of
generating protolanguages for these speakers, he created an initial
vocabulary for both NiloSaharan, proto-Saharan and proto-Sahelian. The
words that he developed do not include fish or fishing terms (line,
net, hook, harpoon). This early vocabulary does have herding terms and
words for 'goat', 'young goat', 'cow', 'corral' and such. No other
writers dealt with this topic.

The Central Sahara is punctuated by large stone
outcrops--massifs--that create their own microclimate. In some cases,
they represent a refuge for rare species, extinct everywhere else.
Work by Henri Lhote in the 1950's documented the varied and colorful
rockpaintings found in the massifs. Grouped into 23 styles, they are
grouped as 1. Bubalus (extinct buffalo) hunters, early Neo- lithic; 2.
'Bovidian' pastoralists (considered Neolithic); 3. Equine phase,
involving pastoralists with chariots and cavalry; 4. Phase of the
camel, 1 AD. These groupings are disputed, but the images show us a
wild-animal phase, then so-called 'Roundhead' figures. These appear to
be multi-ethnic, including a 'Negroid' population.

The pastoralist period involved humpless cattle with large curved
horns, similar to the ancient Egyptian Longhorn. Features of the
people's life resemble activities of the Peul/Fulani, a contemporary
West African pastoral group. Some of the boat images re- semble those
on Egyptian monuments, raising yet other possibilities. Pastoralism
appeared about the time that weather condi- tions became considerably
drier (7000 BC), suggesting that it was a selected response to
changing conditions.

The equine phase and its suspected timing may represent the arrival of
the "Peoples of the Sea", groups that left Crete about 1500 BC (around
the time of the Trojan War) and migrated northeast, east and
southeast. The Biblical Philistines are one such group. Cretans
arrived in NE Africa about 1200 BC, joining with the Libyans and
attacking Egypt. Similar groups may have moved in from the coast and
entered the central Sahara via the caravan trails. If so, this
movement is more a political one than a response to climate change in
the central Sahara, although its outcome would affect the local
population.

Although the rock art isn't datable, it nevertheless shows us several
different worlds of the central Sahara. The earliest involves Africa's
megafauna (lions, elephants, etc) and Negroid peoples. Another one
shows herding people with cattle. Some features of these images recall
West Africa, others, Egypt. The herders look more like Somali people,
with narrow noses, thin lips, straight hair. Probable intruders with
horses and chariots are seen and, finally, the camel makes its
appearance. Are the earlier people migrants from North Africa, from
Egypt or from elsewhere?

Dhar Tichitt in southern Mauritania has been instructive as showing
the cultural response to a drier climate. Digging revealed eight
phases, from hunting megafauna (2000 BC), to limited hunting,
gathering and herding (1500-1100). Subsequent phases included
significant milling. The involved plant went from cramcram, a spiny
famine food, to millet and sorghum. Identification of the species
showed that the people had switched from gathering wild grasses to
planting them, in about 100 years. Such speed is unheard of under
normal circumstances, and suggests that the people were somehow
"presensitized" to cultivation, perhaps via a smaller outgroup that
grew up with farming and then migrated here. Both herding and planting
were presumably responses to unfavorable climate. The site was
abandoned after horses and metal weapons arrived, possibly with the
charioteers described above.

The future of the central Saharans was not always the same as at Dhar
Tichitt. Evidence suggests that the people migrated, some southwest,
some southeast, some perhaps north, following the drying riverbeds as
they sought sites where they could sus- tain themselves. Since West
Africa had not yet been favorable to settlement, due to its dense
forests, the central Saharans may represent some of the early
ancestors of some of these peoples.

Return to the H-Africa Home Page
http://www.h-net.org/~africa/biblio/Winshall.htm

posted 28 July 2004 03:16 PM            

Sahara desert born 4,000 years ago

Friday, July 9, 1999 Published at 12:37 GMT 13:37 UK

By BBC News Online Science Editor Dr David Whitehouse

Using a new computer simulation of the Earth's climate, German scientists say that the Sahara underwent a brutal climate change about 4,000 years ago.

Over a very short time scale - possibly as short as 300 years - it went from grasslands with low shrubs to the desert we are familiar with today. Summer temperatures increased rapidly and rainfall almost ceased. The change devastated many ancient cultures and caused those that did survive to migrate elsewhere.

Scientists at the Potsdam Institute for Climate Research say that the desertification of the Sahara was one of the most dramatic changes in climate over the past 11,000 years.

The loss of agricultural land to the desert may have been one of the reasons why early civilisations developed along the valleys of the Nile, the Tigris and the Euphrates.

Feedback mechanism

Slight climate alterations caused by subtle changes in the Earth's orbit around the Sun were amplified by a climatic feedback mechanism.

Some 9,000 years ago the tilt of the Earth's axis was 24.14 degrees; today it is 23.45 degrees. Today, the Earth is closest to the Sun in January. Nine thousand years ago, our planet was closest to the Sun at the end of July.

The changes in the tilt of the Earth occur gradually. However, the interplay of atmosphere, ocean and landmass can react to these changes in abrupt and severe ways.

The climate model suggests that land use by man was not an important factor in the creation of the Sahara.

http://news.bbc.co.uk/1/hi/sci/tech/390097.stm

posted 28 July 2004 04:26 PM            

quote:

---

Holocene followed the last glacial age, about 12,000 BC. The
temperatures in the Sahara became appreciably warmer and the climate
demonstrated a lower evapotranspiration rate. The Intertropical
Convergence Zone (ITCZ), the line along which north and south weather
fronts converge, seems to have moved several hundred miles to the
north. Since, in general, African rainfall north of the equator
increases as one heads south, the shift of the ICTZ resulted in
Saharan and sahelian zones receiving increased rainfall.
[/B]

---

* I wonder if people keep in mind when discussing changes in the North African climate over time that we are generally discussing 'wetter' vs. 'dryer' phases, much more so than 'hotter vs. 'colder'. There has never been documented to be a genuine cold climate region of Northern Africa (mountains nothwithstanding) for any significant period of time.

Note: a wetter phase due to the tropical convergence zone moving northward is generally associated with a warmer climate, as stated above. (the convergence zone is formed over the area of lowest atmospheric pressure, where low pressure = heat, when it moves north, the northern hemisphere = warmer)

* When discussing effects of climate on population it may be important to keep in mind that there is not historically a sharp and consistent climactic distinction between the hot wet climates of the south, the milder
dry climates of the north central, and the cooler wetter climates towards the coast.

* Some theories of how climate effects phenotype (and which i do not entirely subscribe to), do not correlate completely to specific North African climates. For example: narrow nasal index (like Nilotic type) might either correlate to dry climate or cold climate (which Africa has never had). Broader nasal index (Bantu type) might correlate to warm climate or wet climate. Or maybe not.

For instance...when the climate is both warm & dry (typical sahara)...then almost any theory regarding nasal indices can be made to fit.

One thing that is clear, is that anthropologists have been able to identify a great deal of diversity native to Africa, and normalize said diversity by bringing it under a common umbrella: hence the term, Africoid.

posted 28 July 2004 04:54 PM            

quote:

---

* Some theories of how climate effects phenotype (and which i do not entirely subscribe to), do not correlate completely to specific North African climates. For example: narrow nasal index (like Nilotic type) might either correlate to dry climate or cold climate (which Africa has never had). Broader nasal index (Bantu type) might correlate to warm climate or wet climate. Or maybe not.

---

In both ancient and modern Egypt there is an assortment of nasal types. Most tend to range around convex and concave to high bridged to narrow nasal indexes. What is unsual is sometimes even lighter complexion individuals in Egypt have these features;yet darker Upper Egyptians have narrow to broad profiles.

The Sahara in it's development was mostly savanna type areas much like modern day Kenya,and other areas were very moist. The original homeland of the Bantu is somewhere between southern Nigeria/Gabon which they disperced from around 800 B.C. The rest of the Western African population around the Sahel has their origins in the once fertile Sahara.

Nilotic types sometimes have both profiles of broad or narrow. Most are tall and skinny to hold in head or sweat.

Cosider also that many lighter skinned Northern Africans might either be migrants from the Near-East,or Khoisan types evovled to a Mediterranean costal climate.

Interesting overview none-the-less. Thanks for your insight.

BTW,the pastorial herders in the rock art are the ancestors of the Fulani people. The customs on the rock art is almost identical to modern day Fulani people called the litori water ritual.

posted 28 July 2004 11:35 PM            

quote:

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Originally posted by ausar:
Cosider also that many lighter skinned Northern Africans might either be migrants from the Near-East,or Khoisan types evovled to a Mediterranean costal climate.

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posted 28 July 2004 11:47 PM            

Heiko Riemer
Holocene game drives in the Great Sand Sea of Egypt?
Stone structures and their archaeological evidence

posted 28 July 2004 11:51 PM            

Michel Barbaza et Marc Jarry
Le site de Tondiédo à Markoye (Burkina Faso). Élaboration d’un modèle théorique pour l’étude de l’art rupestre protohistorique du Sahel Burkinabé

posted 29 July 2004 12:06 AM            

quote:

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Originally posted by Thought2:
[QUOTE]Originally posted by ausar:
[b] Cosider also that many lighter skinned Northern Africans might either be migrants from the Near-East,or Khoisan types evovled to a Mediterranean costal climate.

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[/B][/QUOTE]

Are you trying to highlight the relationship between the two individuals or the contrast?