Download Lecture 31 (4-25-11)

Recent genetic evidence on the Neandertal/modern human
relationship
The Neandertal Genome
• Reported in journal: Science, May 2010
• Modern human/Neandertal divergence c. 440,000 ybp.
• Modern humans arrived in the Middle East c. 100,000 ybp
and there were Neandertals there until c. 60,000 ybp.
• Last of the Neandertals in Europe c. 30,000 ybp.
• Vindija Cave site, Croatia (close to Shanidar Cave)
• Bone fragments from three different Neandertal females
provided nuclear DNA fragments for sequencing.
• Bone dates: 38,000 ybp and 44,000 ybp.
• Challenges:
• 97% of the DNA in the bones was fungal & bacterial.
– Had to be identified and removed.
• Many Neandertal DNA fragments were only 40-50 base pairs
in length.
– Had to be aligned
• > 4 billion nucleotides sequenced from fragmentary DNA
– (c. 60% of the genome).
• Compared to the genomeS of five contemporary humans
• South Africa (San), West Africa (Yoruba) , China (Han), New
Guinea (Papuan), and France (European).
• Of these five individuals, non-Africans had 1-4% Neandertal
DNA markers.
• None of the two Africans had Neandertal DNA.
• An enigma! Not only was Neandertal DNA in the
European, it was in the individuals from China and
New Guinea as well.
• Therefore, Chinese and Papuans are as closely
related to Neandertals as Europeans.
• Neandertal fossils have never been found in either
eastern Asia or New Guinea.
• Therefore, interbreeding must have taken place in
the Middle-East region before modern humans
expanded their range and diverged in other areas.
• None of the three Neandertals had genetic markers
of modern humans.
• Gene flow was unidirectional: from Neandertals into
modern humans.
• Follows a general pattern of colonization between
closely related populations.
• Gene flow movement most often from the resident
population into the colonizing population, not the
reverse.
• Resident population: Neandertals
• Colonizing population: anatomically modern humans
Sophistication of recent stone tool manufacture
Discovered in 1957
Two amateur archeologists
Olsen-Chubbuck site
C. 140 mi. SE Denver
Wind erosion had exposed
A bone bed in an ancient
Arroyo.
c. 1/3 excavated by Olsen
and Chubbuck, then they
Notified C.U. archeologists
Excavation in 1958 and
1959.
Cross-section of the
arroyo
Buried by wind-borne
deposits.
A bison trap.
Part of the excavated
arroyo.
Arroyo was 170 feet long
Remains of 193 bison
Bison occidentalis
not Bison bison
Bones in three layers:
Bottom: complete
skeletons of 13 individuals
Middle: bones of partially
butchered individuals
Top layer: individual bones
and partially articulated
bones in similar piles.
Dated at 6,500 ybp
Dispelling the idea
1. that stone tools
were easily
manufactured.
2. that tool types
defined different
groups of people
(typology)
Material culture
Scottsbluff points:
Scottsbluff tradition
Eden points:
Eden tradition
Milnesand points:
Milnesand tradition
A few of the
projectile points
associated with
the bison bones.
Reconstruction of events
1. Time of year.
2. Wind direction
3. The stampede.
Social structure
75% of the bison were
completely butchered.
Based on numbers in various age
classes, the number of butchered
bison would have produced
56,640 pounds of fresh meat
4,000 pounds of edible internal
organs
5,400 pounds of fat.
100 people could have completed
the butchering in half a day.
Enough meat, internal organs,
and fat to feed a group of 150 for
23 days.