Recent genetic evidence on the Neandertal/modern human relationship

1. Recent genetic evidence on the Neandertal/modern human relationship

2. 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.

3. 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.

4. 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.

5. 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

6. 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.

7. Cross-section of the arroyo Buried by wind-borne deposits. A bison trap.

8. 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

9. A few of the projectile points associated with the bison bones. 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

10. Reconstruction of events 1. Time of year. 2. Wind direction 3. The stampede.

11. 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.