The History of the Sahara's climate changes

The Sahara Desert. It's the hottest and the largest desert in the world-as big as the U.S.! In fact, all the sand in the Sahara alone could cover and bury the earth eight inches deep (try comprehending that). It's been so hot in the Sahara, that in Lybia in 1922, it reached 136 degees Fahrenheit, the hottest recorded temperature in the world. It's a record still not beaten.

The Sahara became a barren desert 3 million years ago. It then started climate cycles; every 20,000 years the Sahara changed and still changes from wet to dry/dry to wet within a couple of centuries. Scientists have proved that the pattern of the Sahara's climate changes follow the Earth's wobble (also known as precession), which of course happens to go through an entire cycle every 20,000 years. The last time the Sahara changed from wet to dry was 7,000 years ago, so in 13,000 years it will change back to a subtropical jungle.

Evidence that most of the Sahara was once an ocean 40 million years ago can be seen in the great pyramids. If you look closely at the blocks, you can see fossils of single celled organisms called nummulities. They make up 40 percent of the great pyramids, which proves that the Sahara was once under a great ocean.

In a northern valley of the Sahara called Wadi Al-Hitan (which translates to Valley of the Whales), there are many fossils of whale bones (called Durodons), which date back to around 40-36 million years ago. They were also around 21 feet long on average. They swam in an ancient ocean called the Tethys Sea (it connected the Atlantic to the Pacific back then), which disappeared right before the Durodons went extinct. The reason the Tethys sea disappered is because the African plate collided into the European plate. But even though they collided, the African plate didnt stop, and as a result it pushed the Tethys Sea out. But part of it got trapped into Africa, which also trapped all the Durodons. The remnants of the Tethys Sea eventually dried up, causing the whales to go extinct.

In 1981, NASA took Satellite images of the Sahara using a new kind of radar. They discovered dry ancient water canals 16 feet under the desert, where scientists found millions of shells in what seemed to be the shore of a giant lake as big as West Virginia. It existed 90,000 years ago.

While drilling for oil in the Sahara, great quantities of water were discovered. This is called the Nubian Aquifer. It sits below Egypt, Lybia and Sudan. It contains as much water as the great lakes.

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Hi. My name is Dakota. Welcome to my blogs. Check in often for the latest postings on my "human history" blog, and polls about stuff on my "stuffland" blog. If you have any questions or comments regarding things about my blogs you may type one in the comments "area." Thank you and enjoy the blogs.


The first humans/hominids originated in Africa around 7 million years ago. Called by the nick-name "Toumai", it's real name is "Sahelanthropus tchadensis". Discovered in Chad, Africa, in 2001, it is the oldest hominid fossil discovered so far.

Six million years ago, we took the first step into becoming human (walking upright), which separated us from the apes.

An African scientist named Zeresenay Alemseged discovered a fossil of one of our ancestors. He called it "Salam", the Eithiopean word for peace. It was 3.3 million years old. He recognized which one of our ancestors it was: Australopithicus Afarensis, who walked on two legs. It is the same species as the famous "Lucy", discovered in the 1970's by Donald Johanson. Salam died around age three, based from the adult teeth, which can only be seen under a CT scan. This was important because regular apes almost fully mature by age three. Clearly, Salam was not that mature when she died, which gives evidence that are our ancestors were separating from the apes.

Hominids eventually migrated in at least two different time periods (one around 1.8 millon years ago, and the other about 200,000 years ago) out of Africa, creating several hominid (human) species all over the world. Some were human-like species, like Homo Erectus, and others were more ape-like.

The most famous Homo Erectus is Turcana Boy, who lived around 1.3 million years ago.

As recently as 50,000 years ago, there were at least four different types of humans living at the same time. Our human species is called "Homo Sapiens", which means "wise man" in latin. Another human-like species, which was a very close relative to us, was called "Homo Neanderthal", which was named after the Neander Valley in Germany where the original one was found. Homo Sapiens (us) and Homo Neanderthal came from the same ancestor, which is named "Homo Heidelbergensis". The Neanderthals were very successful. They lasted around 400,000 years; twice as long as we have. Did you know that the Neanderthals only recently died out (they went extinced between 25,000 to 30,000 years ago). Just think that some of your friends could have been Neanderthals!

By the way, every human living today is descended from a group of about 600 individuals, which is why that every human's genes are 99.9 % identical.

The Neanderthals (for dummies)

The Neander Valley was named after a minister, Joachim Neumann, who used to take walks there in the late 17th century. Neumann composed many hymns, some of which are still sung today. Wanting to use a Greek pseudonym, Neumann, whose name means "new man", chose "Neander", a translation of his name into Greek. By a strange coincidence, the "New Man Valley" named for him after his death gave its name to a new type of human that was discovered there.


Homo Aragaster migrated through Asia out of Africa 1.8 million years ago and eventually evolved into "Homo Erectus" and reached "Java" which is in Indoniesia, also known as "Java Man". DNA testings of the "Y" chromozone makes clear that Homo Erectus was not our ansestor.

During this migration, however, Homo Aragaster evolved into another species called " Homo Heidelbergensis". Anthropologists now believe that "Homo Erectus" was a dead end. But "Homo Heidelbergensis" branched into us and separatly to Homo Neanderthal.

Java Man's desendants survived until around 100,000 years ago.

Early Humans Evolution Video

The basic timeline of discoveries of ancient human remains/fossils

1856-Neanderthal fossils are discovered in the Neander Valley in Germany.

1859-Charles Darwin publishes "The Origin of Species", which asserts that all living organisms-including humans-were a product of evolution.

1868-Cro-magnons,a group of Europians modern humans (Homo sapiens) that lived 40,000 to 10,000 years ago, are discovered in France.

1871-"The Descent of Man", by Charles Darwin, points to Africa as the cradle of humankind.

1879-Prehistoric cave paintings created from 15,000 to 13,000 years ago are found near Altimaria, Spain.

1891-Java Man, the first "Homo erectus" fossil ever found, is discovered by Eugene Dubois on the island of Java in Indonesia but is dismissed as an ape or a deformed human.

1908-"Piltdown man" is unearthed in England, providing support to the idea that Eurasia was the birthplace of human kind. In 1953, the bones are exposed as a hoax.

1911-Arthur Homles of Imperial Collage London develops radiometric dating, which paleontologists later adopt.

1924-Raymond Dart pieces together the Taung child, the first early-human ancestor found in Africa. The 2.5 million-year-old fossil ismet with skepticism in Europe.

1929-Peking man, or "Homo erectus", is discovered in China and presented as the missing link between apes and humans, eclipsing Dart's Taung child.

1936-Robert Broom uncovers the first adult australopithecine in South Africa, lending authenticity to the Taung child fossil.

1960-Louis Leakey finds "Homo habilis", then the most ancient representative of the "Homo" genus, in Tanzania.

1961-Radiometric dating puts Nutcracker man at 1.75 million years old, not the estimated 600,000, pushing back the human evolutionary clock.

1967-Human and chimpanzee DNA show our lineages split from a common ancestor five million years ago.

1974-Ethiopia's "Lucy", the most complete extinct hominin fossil yet found, proves that humans walked upright three million years ago.

1978-Fossilized footprints at Laetoli in Tanzania provide evidence of upright-walking 3.5 million years ago.

1984-Eighty percent of Turkana boy's 1.6-million-year-old skeleton is discovered in Kenya, making it the most complete extinct hominin skeleton ever found in Africa.

1992-1994-The 4.4-million-year-old apelike fossil of "Ardipithecus ramidus" is found, making it the earliest known hominin.

1997-THe oldest-known stone tools, are found in Gona, Ethiopia, and dated to 2.6 million years old. Also, Neanderthal DNA is first extracted from a fossil.

2000-An "Orrorin tugenensis" femer, found in Kenya, pushes upright walking back 1.5 million years, to six million years ago.

2001-Toumai, a six-to seven-million-year-old fossil, is found in Chad making "Salelanththropus tchadenis" the oldest known human ancestor. It retains this status to this day.

Ancient tools

Ancient tools

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Mode 2 stone tools. Quartzite, flint 350,000 years old tools like these from Atapuerca have been carefully shaped on both sides to a predetermined form. These 350,000-year-old tools resemble artifacts produced in Africa around one million years earlier.

Hair DNA Documents Forgotten Migration

Encased in ice for 4,000 years, a clump of prehistoric hair gave up its secrets to the University of Copenhagne's Eske Willerslev, the first researcher to sequence an ancient human genome. The hair, dug up in 1986 in Qeqertasussek, Greenland, revealed that its owner was a male with brown eyes, thick brown hair, dry earwax, and shovel-shaped incisors. He was also prone to early baldness, according to an analysis published in Nature in February, 2011.

"Hair is the best material for genomics," Willerslev says. It contains less DNA than other sources, but it is not porous or easily contaminated. His sequencing yielded about 80 percent of the genome. Most significantly, analysis of the hair revealed that its owner was closely related to the Chukchi people, who live at the eastern tip of Siberia today, suggesting his ancestors traveled to the New World independant of the migrations that gave rise to Native American and Inuit peoples. "This was a previously unknown migration," Willerslev says. "It shows the true power of genomics to decode history." His team is now looking at the hair of ancient mummies in the Americas.

Source: Discover (magazine); Issue: Jan./Feb. 2012, article by Jill Neimark