1. The Evolution of Humans

2. The Beginning
Human evolution began approximately 60 million years ago with the earliest primates
Ancestral Primate
Mammals with long snouts, sharp teeth and large eyes
Most likely lived in trees, feeding mostly on insects

3. The Beginning cont… Over time they developed 3 distinct traits
More flattened molars suited for a plant diet
Grasping hands and feet with opposable first digits
Forward-directed eyes that binocular vision and depth-perception
Over the next 20 to 30 million years these mammals evolved into prosimians and anthropoid organisms

4. PROSIMIANS
The living members of this group include lemurs – which are currently found in Madagascar.
They have:
long faces, some digits and claws, and some have nails
mobile toes, but not-opposable

5. LEMUR

6. ANTHROPOIDS Present-day monkeys, apes and humans
Almost all are diurnal and feed mainly on fruits and leaves
Evolved large brains for processing information
Live in complex social groups and have prolonged care for young
As Gondwanaland (a super continent made up of South America, Africa, India, Australia, and Antarctica) separated to S. America and Africa two groups of monkeys evolved:
New World Monkeys (South America - evolved in isolation)
Old World Monkeys

7. NEW WORLD MONKEYS Ex. Spider monkeys Long grasping tails Flat noses
Live in trees

8. OLD WORLD MONKEYS Ex. Baboon, Rhesus monkey Lacked long grasping tails
Protruding noses

9. HOMINOIDS Includes the apes and the humans
Apes include: gibbon, orangutan, gorilla and chimpanzee
All lack tails
Most are ground dwelling
Longer front limb and larger brains relative to body size

10. Hominoid Ancestor
During the Miocene period (25 mya), the weather began to change.
The continents were drifting into their present location, and as a result the weather became dryer and colder
This changed the tropical forest into more of a grassland habitat

11. Hominoid Ancestor Cont…
During this time, apes became abundant
Among the Miocene apes, the members of the dryopithecus are of particular interest – they are thought to be a possible hominoid ancestor
The bones of their feet indicate they walked on the ground (they still walked on all fours) using the knuckles of their hands to support their weight (like today’s apes)

12. DRYOPITHECUS

13. HOMONIDS
Just when humans split from apes is not known, but the common belief is that it occurred approximately 6 million years ago
A cooling trend is increasing grasslands
We do not know what first homonids were like, but assume they came out of the trees into the grassland, and began to walk upright (bipedal) to help them survive
Spot predators and prey over tall grasses
Free hands to perform other functions

14. Hypothetical phylogenetic tree of hominoids

15. AUSTRALOPITHECINES (Southern Apeman)
3.5-4 mya
4-5 feet in height
Bipedal
Non-opposability of big toe
Small brain
Many species of Australopithecines:
afarensis (Lucy)
africanus
robustus
Relationship is in dispute!!

17. A. afarensis and A. africanus
Most primitive
Smallest brain
Large canine teeth
Protruding face
Limb features show erect walking

18. A. robustus
Larger
More varied diet (vegetarian)

19. Possible Explanation??

20. Homo habilis Appeared more than 2 mya (fossils)
Humans evolved in Africa
Larger brain size (30% greater than A. africanus)
Males larger than females

21. Homo erectus
1.6 mya
Shape of skull indicates intellect, memory and language
Improved tools
Fossils found primarily in Africa, but also Asia
Smaller teeth
Larger brain
May have evolved into two or three species of early humans

22. Homo neaderthalensis Neanderthals 250,000 to 30,000 years ago
Named after Neanderthal Valley, Germany
Brain was larger than today’s human brain
Advanced tools, made blades, cave drawings
Buried with flowers and tools
May have been capable of complex speech

23. Homo sapiens 100,000 years ago to present Large brain size
Forehead that rises sharply
Eyebrow ridges that are very small
A prominent chin
More sophisticated tools
Some scientists consider Homo neanderthalensis to be a subspecies of Homo sapiens, rather than a species unto itself.

24. Monogenesis Hypothesis
Proposes that H. sapiens evolved only in Africa and the migrated to other continents
Displaced the Neanderthal and other descendants of earlier H. erectus populations
Regional genetic differences in humans evolved with the past 80,000 to 100,000 years, since H. sapiens left Africa
Supported by molecular evidence (DNA)