posted 14 March 2005 08:37 PM            

Africa 11 thousand years ago:

Africa 09 thousand years ago:

Africa 05 thousand years ago:

Africa currently

From around 150,000 to 130,000 years ago, Africa experienced colder and more arid than present conditions. About

130,000 years ago, a warm phase moister than the present began, and this lasted until about 115,000 years ago, with

greater rainforest extent and the deserts almost completely covered with vegetation. Subsequent cooling and drying

of the climate led to a cold, arid maximum about 70,000 years ago, followed by a slight moderation of climate and

then a second aridity maximum around 22,000-13,000 14C years ago. Conditions then quickly became warmer and moister,

though with an interruption by aridity around 11,000 14C years ago. A resumption of warm, moist conditions led up to

the Holocene 'optimum' of greater rainforest extent and vegetation covering the Sahara. Conditions then became

somewhat more arid and similar to the present. Relatively brief arid phases (e.g. 8,200 14C y.a.) appear to

posted 14 March 2005 10:20 PM            

Observe that grassland stretches from west coast to east coast, always has. The latitude and extent of it expands and contracts as the climate cycles over and again thru wet and dry phases, but east and west Africa have never been substantially cut off from one another.

posted 14 March 2005 11:33 PM            

quote:

---

From around 150,000 to 130,000 years ago, Africa experienced colder and more arid than present conditions.

---

posted 15 March 2005 06:35 AM            

quote:

---

Originally posted by Super car:
Earlier it was thought that Homo Sapiens Sapiens appeared around 150, 000 years ago. Further studies show that they may well have been around 200,000 years ago. In light of what you posted earlier (provided below), what should be said about the climatic conditions during 200,000 years and how this affects the evolutionary process of humans?

---

What should be said is that climate varies everywhere and the variations involve many complex interrelated cycles, which are in turn related to ocean currents, orbital axes variation, release of carbon dioxide from volcanos and many other phenomena.

However, tropical regions such as Africa do not vary as wildly over time as do northerly climes such as North America or Europe.

Europe and North America vacilate between being largely ice covered wastelands to milder more temperate zones.

Africa varies largey in that the deserts, grasslands and rainforests spread, and retreat, with human populations expanding and retreating along with it. During the last wet phase about 10,000 years ago much of the sahara was fertile, with crocodiles, giraffes, lakes and substantial human populations as well.

The drying of this area is likely one of the factors that caused populations to converge into the Nile Valley and also expand across the Levant. Populations in Africa respond to climate change primarily by migrating.

The precursors of the indigenous somatic variations that exist in Africa today have existed for many 10's of thousands of years because the same range of climate variation has exited during this time, and repeated over and again. And of course this is notwithstanding the climatic constant of tropical solar radiation, to which native African dark skin tone is adapted.

The situation in Europe could not be more different....

About 24,000 years ago, the last ice age began, with mountain-sized glaciers moving across most of Europe. Paleolithic Europeans retreated before the ice, finding refuge for hundreds of generations in three areas: what is now Spain, the Balkans and the Ukraine. - PA Underhill.

posted 15 March 2005 09:55 AM            

There are 3 principal factors directly effecting the amount of energy the earth gets from the sun. The solar cycle, orbital eccentricity and, perhaps the most important... orbital tilt.

The greater the tilt in the Earth's axis.....the MORE solar energy is received in the mid and high latitudes....and less (than usual) is received in the tropical and equatoral regions.

The smaller the tilt in the Earth's axis...the more solar energy is received in TROPICS, and less in the mid and high latitudes.

It is this condition that is one of many interrelated culprits in triggering ICE AGES.

25 thousand years ago the Earth's axis tilt was near it's minimum. This means Northern EurAsia may have recieved less UV at this time, but tropical East Africa may have actualy recieved more.

Pale skin tones developed in Eurasia at around this time. In tropical Africa, pale skin is and always has been maladaptive (ie = skin cancer).

Native tropical Africans have dark skin for this reason and always have- throughout the entire history of modern human evolution from 150kbp until today.

posted 16 March 2005 05:41 AM            

Apehelion - when the earth is furthest from the sun.

Perhelion - when the earth is closest to the sun.

Presently the perhelion occurs in January and apehelion in July. To those living in the Northern Hemisphere this may seem odd, but this actually makes the seasonal extremes in the Northern Hemisphere less severe and those in the Southern Hemisphere more severe.

10 thousand years ago, the reverse was the case, 20 thousand years ago, it was as it is now.

Each of these phenomena have a different time scale and so a complex relationship on the earth's climate, often effecting the northern vs. southern hemishere and the topics vs. the high latitudes, in opposite ways, and with a minimal effect on actual UV sometimes having a major impact on climate especially in Northern Eurasia.

Africa's native peoples are primarily adapted to a high UV environment with differing ranges of savanna grassland, desert and rainforest.

posted 19 March 2005 08:33 PM            

What is now the sahel zone, the present climatic abode of peoples such as the Taureg and Fulani, made up almost the entirety of the Northernmost regions of the continent, and true Sahara, essentially ceased to exist, and sub-sahara during this formative period for African culture is somewhat of a misnomer.

Stop around lunchtime at Dabos to see the stunning, almost life size, recently discovered neolithic rock engraving of a giraffe. Rock engravings and paintings in this part of the Sahara date as early as 8-6,000BC. The giraffe at Dabos is another testimony that the Sahara was once wet and green http://www.exploreafrica.net

posted 20 March 2005 03:14 PM            

quote:

---

Originally posted by rasol:

Observe that grassland stretches from west coast to east coast, always has. The latitude and extent of it expands and contracts as the climate cycles over and again thru wet and dry phases, but east and west Africa have never been substantially cut off from one another.

[This message has been edited by rasol (edited 14 March 2005).]

---

posted 20 March 2005 04:42 PM            

quote:

---

Originally posted by kifaru:
Thank you for making this point. I am always somewhat amazed by the fact that people believe that africans cannot now or could not then travel long distances or traverse hostile terrain of their own volition.

---

It is also interesting to consider, in terms of defining Africa by geography and then by ethnicity....where exacty does East Africa end and west Africa begin, and why...based on what geographic feature, cultural facet, genotype or physical feature?

In truth you are likely to find affinity on all fronts from East to West for reasons shown on the above climate maps.

However since anthropology revealed the rift valley origins of humanity, the tendency has been to attempt to remove East Africa...from Africa.

posted 26 March 2005 05:31 PM            

quote:

---

Originally posted by rasol:
AFRICA:

The Fertile Valleys of the Nile, Indus, Tigris, Euphrates, and Yellow rivers were able to support large populations and it was here that great 'civilisations' of the Ancient world emerged

more...

---

Thought Posts:

http://www.cru.uea.ac.uk/~e118/publications/Brooks-BeyondCollapse-abs.pdf

posted 26 March 2005 08:27 PM            

quote:

---

Originally posted by rasol:
Thought Posts:

http://www.cru.uea.ac.uk/~e118/publications/Brooks-BeyondCollapse-abs.pdf

---

Thought Writes:

posted 27 March 2005 09:59 PM            

quote:

---

Originally posted by Thought2:
Thought Writes:

Of course we now know that some groups like Africans in Early Khartoum have been sedentary since the early Holocene but did not develop hierarchical complex political structures.

---

??

posted 29 March 2005 06:22 AM            

In general, studies show that modern humans first arose in Africa about 100,000 years ago and thousands of years later began a long series of migrations, he said. Some groups migrated eastward and humans are known to have existed in Australia about 60,000 years ago. Other groups crossed the land bridge into the Middle East. Humans appeared in Central Asia about 50,000 years ago. From there, the theory goes, some migrated west, arriving in Europe about 40,000 years ago
- Early Europeans, 11-2000 AP

posted 29 March 2005 11:16 AM            

quote:

---

Originally posted by windstorm2005:
Excellent thread!

...What about what Europe was like during corresponding periods?

---

Thought Writes:

posted 05 April 2005 07:37 PM            

quote:

---

First Farmers
Peter Bellwood
2004

"Paleolithic Egyptians, such as those who used Wadi Kubanniya campsites about 20,000 years ago, exploited fish, migrant birds, wild cattle, gazelle, and hartebeest, and used grindstones to prepare a toxic tuber (Cypres rotundus) for leaching prior to consumption."

Thought Writes:

Another interesting fact from Bellwoods book is that he charts the southern boundary of the sahara around Dakhleh and the northern limit of the Tsetse Fly zone around Kadero. Hence the bulk of Africas population during the Neolithic period (8,000 to 3,000 B.C.) would be packed between these two latitudes from the Atlantic to the Red Sea.

---

posted 27 April 2005 10:57 AM            

quote:

---

Originally posted by ausar:
In the Paleolithic period [before 5000 B.C.] the Delta and Nile Valley were virtually uninhabitable. The annual flood [inundation] of the river Nile would have placed all areas of the Nile Valley under water for three months of each year, and at other times it was covered with thick vegetation that provided habitation for a variety of wild animals. In the north much of the low lying Delta was converted with papyrus swamps. At this time people lived on the desert spurs and hunted prolific game. As the climate became drier and the vegitation of the Nile Valley gradually changed , they were able to move down into the valley once the inudation receded . Here during the Neolithic period[c. 5000-4000 B.C.] they began to cultivate the land ,gorwing grain and learning to domesticate animals.

Atlas of Ancient Egypt (Cultural Atlas of) - John Baines; Hardcover

page 59

ISBN: 0871963345

Publisher: Facts on File (July 1, 1980)

---

posted 04 May 2005 12:22 PM            

Since there is no scientific consensus on how to reconstruct global temperature variations during the Holocene
, the average shown here should be understood as only a rough, quasi-global approximation to the the temperature history of the Holocene - http://en.wikipedia.org/wiki/Temperature_record

posted 08 May 2005 05:44 PM            

quote:

---

Originally posted by Thought:

The Horn of Africa During the Last Glacial Maximum:

"Conditions over other parts of Ethiopea are a matter of conjecture. With the evidence of drying in the highlands and the rift valley region, we suggest that **TROPICAL** desert covered much of the Horn of Africa."

---