1. Humans and early hominids
By Edward Zhu, David Flores, and Hammad Ahmed

2. Major features that make us human
Upright posture and bipedal movement
Reduced jawbone and shortened digestive tract
Larger brain
Tool use
Symbolic thought and use of language

3. Hominoids and Hominids
Hominoids are a clade including gibbons, orangutans, gorillas, chimpanzees, bonobos, and humans, along with extinct species that descended from the same ancestor.
Hominids are a clade including humans and all species more closely related to humans than other living hominoids.
A species on the human branch of the evolutionary tree; a member of the family Hominidae, including Homo sapiens and our ancestors.
D K P C O F G S

4. Paleoanthropology The study of human origins and evolution.
Paleoanthropologists have found 20 extinct that are more closely related to humans than to chimpanzees.
Those of which are called hominids

6. Earliest Hominid
The oldest hominid is Sahelanthropus tchandensis, which lived 7 million years ago.
Sahelanthropus and other early hominids shared some characteristics of humans.
Flat canine teeth and flat faces
More upright and bipedal
However had smaller brain

7. Misconceptions
Our hominid ancestors were not chimpanzees or any modern apes.
Chimpanzees and humans are two divergent branches from a common ancestor that wasn’t a chimpanzee or a human.

8. Misconceptions
Human evolution is not a progressive ladder with steps of ancestral hominoids.
If human evolution is a parade, then many splinter groups traveled down dead ends, and several different human species coexisted.

9. Misconceptions
Various human characteristics such as upright position, enlarged brain, did not evolve together at once.
Differing rates of evolution in different features is known as mosaic evolution.

10. Australopiths
The various pre-Homo hominids are classified in the genus Australopithecus (“southern ape”) and are known as australopiths.
They are a paraphyletic assemblage of hominids that lived between 4million to 2million years ago.

11. Australopiths
Australopithecus africanus walked fully erect and had human-like hands and teeth.
However had one-third the brain size of a present-day human.

12. Lucy
In 1974, in Ethiopia, paleoanthropologists discovered a 3.24million-year-old Australopithecus afarensis skeleton that was 40% complete. “Lucy” was only about 1m tall.
Softball sized head, afarenis skulls have a longer jaw.
Artist’s rendition of what A. afarenis may have looked like.

13. Bipedalism
Hominids most likely became bipedal due to the increase of a savanna environment with fewer trees.
Hominids began to walk long distances on two legs around 1.9million years ago.

14. Tool Use Other hominoids can use tools.
Orangutans use sticks to retrieve insects from nests. Chimps use rocks to smash open food.
The oldest evidence of tool use are cut marks found on bones, 2.5million years ago.

15. Early Homo
The earliest fossils that paleoanthropologists place in our genus Homo are those of the species Homo habilis, ranging in age from about 2.4 to 1.6 million years
Stone tools have been found with this species
Giving this species its name “handy man”
Compared to australopiths, H. habilis have a shorter jaw and a larger brain.

16. Homo Ergaster
Existed between 1.9 and 1.6million years ago, they were the first fully bipedal and large brained hominids.
They had longer slender legs for long distance walking, and had more sophisticated tool use.
Their teeth may suggest that they cooked/mashed their food before eating.

17. Homo Erectus
Homo erectus was the first hominid species to migrate out of Africa where they originated 1.8million years ago.
They colonized Asia and Europe and their fossils are sometimes called “Beijing man” and “Java man”

18. Neanderthals Also Known as Homo Neanderthalensis
Discovered in 1856 in the Neander Valley in Germany

19. (Cont...)
At first thought to be considered a stage in evolution of Homo erectus into Homo sapiens
Discovered actually descended from Homo heidelbergensis
Originated in Africa (600,000 years ago) then spread to Europe
Appeared in Europe and the Near East (200,000 years ago)

20. Homo heidelbergensis to Neanderthals

21. (Cont…) Similarity to humans Went extinct 30,000 years ago
Brain same size as present day humans
Went extinct 30,000 years ago
Did not contribute to gene pool of present day humans
Proof is found in their DNA
Compared their DNA to the DNA of Europe, Africa, and Asia
Analysis shows that the Neanderthals form a clad
The Europeans are more closely related to Africans, and Asians

22. (Cont…) Differences to humans Some reasons for this
large middle part of the face, angled cheek bones, and a huge nose for humidifying and warming cold, dry air
bodies were shorter
Had thick bones and prominent brow
Some reasons for this
Lived in cold areas

23. (Cont…)
Earlier humans lacked heavy brow ridges that H. erectus and Neanderthals had
More slender

24. (Cont…) Ability to Control fire live in shelters
made and wore clothing
were skilled hunters of large animals
occasionally made symbolic or ornamental objects

25. (Cont…)
Behaviors
Buried their dead and marked grave with offerings (flowers)
No other early human species practiced this

26. Homo sapiens
Now clear that the ancestors of humans originated in Africa
In 2003, researchers in Ethiopia discovered 160,000 year old fossil of Homo sapiens (oldest known fossil of our own species)

27. (Cont…) Based on research
DNA analysis shows that all living humans are closely related besides Neanderthals
Europeans and Asians have a common ancestor
African lineages branched off more ancient positions on human tree
This suggests that all humans have ancestors that originated from Africa
Supported by analysis of mitochondrial DNA and Y chromosomes from members of various populations

28. (Cont…)
Study of the y chromosome show that humans spread beyond Africa in 1 or more waves
First into Asia then to Europe and Australia
October 2004
Peter Brown, and Thomas Sutikna discovered skeleton of adult hominid that dated 18,000 years ago (Homo florensiensis)
Had smaller brain and was shorter (similar to Australopith)
similar to Homo sapiens
Skull thickness, proportions and teeth shape
Suggests that it descended from H. erectus

29. (Cont…)
“Shrinkage” occurred which isolation on the island resulted in selection for greatly reduced size.
Rapid expansion of Homo sapiens may have occurred by our mental process
Example: using tools
Found more evidence of sophistication
Geometric markings on pieces of ochre (77,000 years old in South Africa)
36,000 year old painting found in caves

30. (Cont…) Gene FOXP2 was identified in 2001 being essential for language
If mutated, suffer a range of impediments and reduced activity
Compared to homologous gene of other mammals
Concluded that it experienced intense natural selection

31. Features that are lost/emphasized as humans evolved.
Spinal cord placement is right under the skull to accommodate the bipedalism.
Larger brain with capabilities of tool use and cognitive thought.
Flatter face, less protruded jaw.

33. Sources