1. The Rise of Humans and the First People in the Americas
ANCIENT HISTORY
The Rise of Humans and the First People in the Americas

2. East Africa: Cradle of Humanity
Genetic studies and fossil evidence show that the earliest stages of human evolution played out in Africa
The “Out-of-Africa” theory
Human history began around 7 million years ago (estimates range from 5 to 9 million)
Around that time, a population of African apes broke up into several populations
One evolved into modern gorillas
The second evolved into modern chimpanzees
The third evolved into humans

3. East Africa: Cradle of Humanity
The Great Rift Valley is home to some of the earliest discoveries of ancient humans
Olduvai Gorge, in Tanzania
“Lucy” in Ethiopia
Fossils indicate that our evolutionary line achieved an upright posture around 4 million years ago
Body size and brain size increased around 2.5 million years ago
Crude stone tools became common around this time
The rift is a narrow zone that is a developing divergent tectonic plate boundary, in which the African Plate is in the process of splitting into two tectonic plates, called the Somali Plate and the Nubian Plate, at a rate of 6–7 mm annually. As extension continues, lithospheric rupture will occur within 10 million years, the Somalian plate will break off, and a new ocean basin will form.

4. Early Humans These earliest proto-humans included:
Australopithecus africanus (like “Lucy”)
Homo habilis
Homo erectus
Although Homo erectus was close to modern humans in body size, its brain was barely half the size of ours
This stage was reached about 1.7 million years ago
Lucy represents several hundred pieces of bone representing about 40% of the skeleton of a female Australopithecus. It was discovered in Usually only fossil fragments are found and only rarely are skulls or ribs uncovered intact; thus this discovery was extraordinary and provided an enormous amount of scientific evidence.
meet “Lucy”

5. Early Humans
Homo erectus was the first human ancestor to spread beyond Africa
Fossils found on the Indonesian island of Java
The oldest “Java man” fossils are thought to date to around a million years ago (but might be older)
About a half a million years ago, Homo erectus began to evolve into Homo sapians, with larger and rounder skulls
Homo erectus skull

6. Early Humans
Early Homo sapians still had brains much smaller than ours, although they did master the use of fire
A separate line of humans called Neanderthals appeared in Eurasia around 250,000 years ago
Neanderthals had larger brains than ours and were the first humans to leave evidence of burying their dead
Neanderthals became extinct around 40,000 years ago – possibly wiped out by Homo sapians
Studies on Neanderthal body structures have shown that they needed more energy to survive than any other species of hominid. When food became scarce, this difference may have played a major role in the Neanderthals' extinction.

7. Early Human Migrations
Homo sapiens moved out of Africa around 200,000 years ago
They spread into Asia, Australia, Europe, and finally the Americas

8. The Great Leap Forward
Human history took off around 50,000 years ago with the emergence of the first modern Homo sapians, called “Cro-Magnons”
The first signs of this leap come from East Africa, followed closely in Asia and Europe
Cro-Magnons had fully modern skeletons and standardized tools of both stone and bone (including fishhooks and needles)
First preserved jewelry, invention of rope, and multi-piece tools (harpoons, spear-throwers, and eventually bows and arrows)
Multipiece weapons allowed Cro-Magnons to kill dangerous animals such as rhinos and elephants at a distance. Rope for nets, lines, and snares allowed them to add fish and birds to their diets.

9. The Great Leap Forward
Some of the best known Cro-Magnon artifacts include their cave paintings and statues
The “great leap” may have resulted from the emergence of modern language

10. Consequences of the Great Leap
Within a few thousand years of Cro-Magnons appearing in Europe, the Neanderthals all disappeared
This strongly suggests that the Cro-Magnons used their superior technology and language skills to displace and/or kill the Neanderthals
The great leap coincides with the expansion of humans into Australia (which was not visible from the Asian mainland)
This would have required watercraft
Not until about 30,000 years later is there strong evidence of watercraft anywhere else in the world (from the Mediterranean).

11. Consequences of the Great Leap
The settlement of Australia coincides with another big first – the first mass extermination of large animal species by humans
Modern Australia has no mammals larger than 100 pound kangaroos, but it used to be home to many large animals
Giant kangaroos
Marsupial lions
400 pound flightless birds
Massive reptiles
Diprotodonts (rhino-like marsupials)
These were wiped out either by hunting, or the destruction of habitat (e.g. humans using fire)
The large animals of Africa and Eurasia evolved alongside humans for hundreds of thousands, if not millions of years. They had ample time to develop a fear of humans, while our ancestors’ initially poor hunting skills slowly improved. The animals of Australia had never encountered humans before.
Skeleton of a Diprotodont

12. Colonization of the Americas
North and South America were the last two continents reached by humans, probably around 15,000 years ago (although there is much debate)
The strongest evidence is that people crossed from Siberia into Alaska, using the Bering land bridge
This land bridge (called “Beringia”) connected Asia and North America at various times during ice ages, when sea levels were hundreds of feet lower

13. Colonization of the Americas
The oldest human remains in the Americas are at sites in Alaska dated around 14,000 years ago
When humans first arrived, Canada was covered by an impassable ice sheet
As the ice age ended, sea levels rose and submerged the Bering land bridge
An ice-free corridor opened in the Canadian ice sheet, allowing humans to pass south into the Great Plains

14. Clovis Sites
Around 13,000 years ago a large number of settlement sites began appearing across the United States and into Mexico
They are called Clovis sites, named after the town of Clovis, New Mexico – where their distinctive large stone spear points were first discovered
Hundreds of Clovis sites are now known
Evidence of humans appears soon after in Amazonia and Patagonia
Chipped from obsidian and other fine, brittle stone, they have a lance-shaped tip and (sometimes) wickedly sharp edges. After discovering Clovis points in New Mexico, scholars looked for traces of them in collections of artifacts from Siberia, the origin of the first Americans. None have ever been found. Clovis points, it seems, were an American invention—perhaps the first American invention.
Patagonia is almost 13,000 km from the Canada-U.S. border. While it might seem surprising that Clovis descendants could reach that far in less than a thousand years – it translates to an expansion of only km a year.

15. American Animal Extinctions
Like Australia, the Americas were originally full of large animals
Herds of elephants and horses
Lions and cheetahs
Camels and giant ground sloths
These animals went extinct around 12-13,000 years ago, shortly after the arrival of Clovis hunters
Skeletons of mammoths have been found with Clovis spear points between their ribs
Megalonyx (giant sloth)
15,000 years ago the American West looked much like Africa’s Serengeti Plains do today.
Glyptodont (South America)

16. Who really got here first?
Whether Clovis hunters really were the first Americans continues to be debated
If there really were pre-Clovis people in the Americas, why is it so hard to prove?
In Europe, there are hundreds of sites that show human settlement long before Clovis hunters appeared in the Americas
Australia has barely 1/10th as many archeologists as in the U.S., but they have discovered over 100 pre-Clovis sites scattered over the whole continent