2. Human Evolution
The fossil record is incomplete but provides evidence to the events in human evolution
DNA analysis provides additional information
Species with common DNA sequences are more likely to have arisen from a common ancestor

3. Homo sapiens “The wise human”
Probably first appeared about 200,000 years ago
60 million years ago an ancestral rodentlike insect eater flourished
Chapter opener

4. Aegyptopithecus 30-40 million years ago (MYA)
Monkeylike animal, size of a cat
Found in tropical forests of Africa, tree dweller
Social
Possible ancestors of gibbons, apes, and humans

5. Dryopithecus 22-32 MYA Oak ape Found in SW and central Europe
One of first hominoids
Ancestor to apes and humans
Lived in trees but could walk
Size of a 7 year old, small brains, and pointed snout
Figure 16.1

6. Hominin Ancestor to humans Fossils from 4-19 MYA scarce
6 MYA hominin line broke off from apes
At least three candidates for first hominin
Ardipithecus kadabba (from Ethiopia)
Sahelanthropus tchadensis (from Chad)
Orrorin tugenensis (from Kenya)

7. Figure 16.2

8. Australopithecus 2-4 MYA Bipedal, not a tree dweller Several species
Flat skull bases
Stood 4 to 5 feet tall
Humanlike teeth
Brain size of a gorilla’s
Hunter-gatherer lifestyle

9. Australopithecus 4.1 MYA A. anamensis 3.6 MYA A. afarensis (Lucy)
- Larger brain, more humanlike skull
- Less prominent face
2.5 MYA A. garhi
- Hunted and butchered meat
- 4.5 feet tall, long arms like ape
- Small cranium, large teeth, apelike face
- Fossils from Afar region

10. A. afarensis “Lucy”
Figure 16.3

11. Homo habilis 2.3 MYA Humanlike cave-dweller Cared intensely for young
First to use tools extensively (habilis means handy)
Coexisted with and was followed by Homo erectus

12. Table 16.1

13. Homo erectus
1 MYA
Shallow forehead, massive brow ridges, brain about 1/3 the size of modern humans
Angled skull-base, possible speech
Social, cooperative, used fire
Male-female pairs
Found in China, Java, Africa, Europe, and SE Asia
Pockets may have persisted until about 35,000 years ago
Figure 16.4

14. Homo sapiens idaltu Lived about 156,000 years ago
Physically similar to modern humans
Probably resembled an Australian aborigine
Figure 16.5

15. Homo neanderthalensis
Split from the human lineage about 516,000 years ago
Lived all over Europe
Reconstructions of skeletons indicates major differences from us
- Larger brains; prominent brow arches
- Muscular jaws; distinct spacing of teeth
- Large, barrel-shaped chest

16. Homo neanderthalensis
Neanderthals coexisted with the lighter-weight, finer-boned Cro-Magnons from 30,000-40,000 years ago
Cro-Magnons had signs of cultures, including: - Communal graves, jewelry, and intricate cave art
For reasons unknown, by 28,000 years ago Neanderthals disappeared

17. Modern Humans
Cave art from about 14,000 years ago indicates that by that time our ancestors had achieved milestones in cultural evolution
- Fine hand coordination; use of symbols
A preserved man, frozen in ice from about 5,200 years ago, is genetically like us
- Ötzi, the Ice Man

18. Molecular Evolution The study of evolution through comparison of:
- DNA and protein sequences
- Chromosome banding
- Genome structure
Mutations occur in DNA over time
Comparing two DNA sequences
- Fewer changes indicate closer relation and more recent divergence
- More changes, more ancient divergence

19. Comparing Chimps and Humans
We have more in common with chimpanzees than any other animal
DNA hybridization and protein comparisons reveal that chimps and humans share 98.7% of their gene-encoding proteins
Comparison of insertions and deletions (indels) suggests that our similarity is only about 96.6%!

20. What Makes Us Human Traits defining “humanness” may be rare
Keratin gene
- Affects hair coverage
- Expressed in chimps and gorillas
- Nonsense mutation in humans
Speech – FOXP2 gene
Hemoglobin genes
- Humans switch from embryonic to fetal versions of hemoglobin
- Longer fetal period, increased brain growth

21. What Makes Us Different
Underlying difference that makes us humans may be in gene expression not the genome sequence
Our genome is like that of the pufferfish, minus many of the DNA repeats and introns
Overall, the human genome has a more complex organization of the same basic parts than simpler animals
- Contains many more duplicated genes

22. Ancient DNA DNA has been isolated from a few well preserved fossils
- 17 million-year-old magnolia leaf in amber
- 4-5 million-year-old insects in amber
Researchers at Penn State University have sequenced nearly all of the mammoth genome from specimens that were flash-frozen at high altitudes

23. Comparing Chromosomes
Karyotypes among great apes differ mostly by inversions
Karyotypes between apes and more primitive primates differ predominantly by translocations
All mammals share identical X-chromosome banding
Synteny is the correspondence of gene order preserved between two species

24. Table 16.2

25. More Genetic Markers Mitochondrial DNA (mtDNA)
- Used to trace maternal lineage
- Lack of DNA repair in mitochondria leads to a faster mutation rate
Y chromosome
- Sons inherit it from their fathers
- Used to trace male lineage

26. Mitochondrial “Eve”
mtDNA sequences of indigenous peoples worldwide were compared to determine the common ancestral mtDNA sequence
Hypothesized ancestral woman lived approximately 170, ,000 years ago in Africa
This is remarkably close to the date of the Homo sapiens idaltu fossils

27. Populating the New World
People spread across Eurasia and elsewhere by 40,000 years ago, and lastly through Siberia
During the last Ice Age (23,000 to 18,000 years ago), people entered the Americas by crossing the Bering Strait from Siberia
Today, Native Americans carry a very distinctive genetic nametag: Five mtDNA and two Y chromosome haplogroups

28. Populating the New World
By 14,000 years ago, Native Americans had arrived inland
- Genetic evidence also suggests that some populations died out
The earliest Eskimos came from a different migration than the one that was ancestral to Native Americans and modern Eskimos
- The left no present-day descendants

29. Figure 16.18