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The story of us: The journey of man by karobi moitra

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The story of us: The journey of man by karobi moitra

  1. 1. The story of us: the journey of man Lecture 12 Biol 241 Dr. karobi moitra
  2. 2. 3 questions: Why are we here? Where are we going? Where did we come from?
  3. 3. Ò  San Bushmen live in Botswana. Ò  They have some of the oldest human genes carried in their DNA. The beginning…………
  4. 4. Ò  San Bushmen are expert trackers and hunters Ò  They hunt different kinds of animals. Ò  San Bushman have an unique language- the click language Ò  And weapons that gave them a hunting advantage 50,000 years ago The amazing story of the san bushmen
  5. 5. Now we will watch this You Tube video clip to learn more about the San (pronounced Saan)
  6. 6. But how do we know That this Journey started in africa? ?
  7. 7. We know because we can trace certain Dna markers from human populations Y-chromosome markers take us ~59,000 Years back into history These markers lead us straight back To the san bushmen M168, m130
  8. 8. Markers on dna A marker on DNA is a landmark that tells you where you are in the genome
  9. 9. Mitochondrial eve and female Mitochondrial markers
  10. 10. Ó  Mitochondria -- the tiny organelles that serve as energy factories inside all human cells -- have their own genome. Besides containing 37 genes that rarely change, they contain a "hypervariable” (HVR) region, which changes fast enough to provide a molecular clock calibrated to times comparable to the age of modern humanity. Ó  Because each person's mitochondrial genome is inherited from his or her mother, all mitochondrial lineages are maternal. Ó  To infer mt Eve's age, scientists must convert the measures of relatedness between random blood donors into a measure of time to translate the differences between gene sequences into how they evolved in time Mitochondrial dna
  11. 11. Mitochondrial haplogroups A mtDNA haplogroup is defined as all of the female descendants of the single person who first showed a particular polymorphism, or SNP. SNP: Single nucleotide polymorphism- change in a single base of DNA mtDNA SNP identifies a group who share a common ancestor far back in time. SNP markers are found in all 3 regions of the mtDNA: HVR-1, HVR-2 and coding region
  12. 12. Mapping snp’s on mt dna A SNP is like a landmark or marker on DNA which you can follow to find the same marker (or sets of markers) in other individuals. Mitochondria eve had all the human sets of markers indicating the root of humans
  13. 13. Mapping snp’s on mt dna A SNP is like a landmark or marker on DNA
  14. 14. SNPs have reference numbers: rs267601453 - rs stands for reference SNP dataBase SNP
  15. 15. Mapping snp’s on mt dna
  16. 16. Mitochondrial eve
  17. 17. Mitochondrial eve
  18. 18. Mitochondrial eve ~ 150,ooo years ago
  19. 19. Mitochondrial haplogroups mtDNA analyses provided our first genetic window into the past, detailing the history of maternal lineages across human populations. The oldest mtDNA haplogroups are found in Africa (L1, L2 and L3; see figure). The pan-African haplogroup L3 radiated to form MACROHAPLOGROUPS M and N. Macro-haplogroups M and N arose in North Eastern Africa, and individuals that had M and N mtDNA subsequently left Africa to colonize Europe and Asia approx60,000–80,000 years ago
  20. 20. Mitochondrial haplogroups Haplogroups H, I, J, N1b, T, U, V, W and X are mainly derived from macrohaplogroup N and make up almost all of the mtDNA types found in Europe. In Asia, macrohaplogroups N and M radiated to generate mtDNA lineages A, B, C, D, F and G. Native Americans are known to have Asian ancestry because only five haplogroups (A, B, C, D and X) encompass all of the mtDNA variation in the New World, four of which came from Asia67.
  21. 21. Africa: the cradle of life We can also map markers on the Y - chromosome Both The mitochondrial dna and Y-chromosomal dna has less dna To deal with hence they were Initially chosen Now we can sequence entire genomes In the space of a single day
  22. 22. Africa: the cradle of life We can also map markers on the Y - chromosome Which still takes us back to Africa but only about 59,000 years ago
  23. 23. Technique of Mapping Y chromosome Markers Y-DNA testing involves looking at STR segments of DNA on the Y chromosome. The STR segments which are examined are referred to as genetic markers and occur in what is considered "junk" DNA. STR markers A Y-chromosome contains sequences of repeating nucleotides known as short tandem repeats (STRs)/ microsatellites. The number of repetitions varies from one person to another and a particular number of repetitions is known as an allele of the marker. Individual Y-DNA sequences or STRs which have proved useful in genealogical DNA work are called markers, and each has a name, such as DYS393 in the following example. This example states that the DYS393 marker is 12, also called the marker's "value". The value 12 means the DYS393 sequence of nucleotides is repeated 12 times—with a DNA sequence of (AGAT)12. Y-DNA tests generally examine 10-67 STR markers on the Y chromosome, but over 100 markers are available.
  24. 24. An example of a genealogical test: STR mapping on Y chr
  25. 25. Mitochondrial eve ~ 150,ooo years ago Y chromosome markers ~ 59,000 years ago
  26. 26. So did adam and eve never meet?
  27. 27. On Losing the evolutionary signal………
  28. 28. • 2000 generations ago (50-60 Kya) behaviorally advanced Homo sapiens - the direct ancestors of San and Hadzabe Bushmen were driven by drought to follow their quarry searching for grasslands out of Africa. EVIDENCE: • The click language of the San and Hadzabe does not exist elsewhere in the world • DNA Marker- M168 The journey out of africa
  29. 29. All modern humans were in Africa Until around ~60,000 years ago You were here!
  30. 30. On with the journey………. And so the journey continued through asia along the coastal route and to the continent of australasia
  31. 31. Ò  Before a group of the descendents of the San Bushmen entered Australia they passed through India Ò  Spencer Wells took DNA samples and found a marker that traces back to the San Bushmen tribe. Tracing a route through india
  32. 32. This African haplogroup marker takes us to the temple city of Madurai in the Tamil Nadu district in southern India where genomic screening from a man shows a single nucleotide ancient bloodmarker in his Y chromosome leading back to the San. This is also the site where the earliest archaeological evidence of behaviorally modern Homo sapiens has been found. Tracing a route through india
  33. 33. Ò  Open water along the route was crossed by simple rafts made of logs Ò  The route out of Africa is hypothesized to lead to Southern India then on to Sri Lanka and then Indonesia On to australia
  34. 34. The next genetic evidence for descendants out of Africa shows up at a 45 Kya site in Lake Mungo at Laura in Queensland, Australia. Somehow the aboriginal's ancestors were able to complete the journey (the drop in sea level that provided a continuous land route through Indonesia but still left a 150 mile wide stretch of open sea to reach the continent.) Africa to australia in 20-15000 years Following the m130
  35. 35. Y chromosome haplogroups: Following the M130, haplogroup C The M130 marker
  36. 36. The gateway for migration
  37. 37. The grand central of human migration
  38. 38. The gateway for migration: Central asia
  39. 39. Ò  A group of people from Africa went North to Kazakhstan. Ò  Spencer Wells found a man here with a genetic marker from the people of the San Bushmen tribe To kazakhstan………
  40. 40. Ò  From Kazakhstan people migrated to all parts of Asia and started to multiply. Ò  From here a group of people went North to Siberia and adapted to live in cold climates. Central asia: the M45 marker
  41. 41. About 40,000 years ago sapiens have spread to central asia following the grasslands resulting from cooling climate. An episode of migrations begins that moves people from central Asia - two groups moved east to China's north and south and another group moves down to India. It will take another five thousand years before the first people from central Asia migrate to Europe Wells' earlier expedition in 1998 had provided blood samples from Uzbekistan, Kyrgyzstan, and Kazakhstan and he reconnects with a man named Niyazov -a Kazakh Turk who lives in Kazakhstan near the border of Kirgyzistan. Niyazov has African markers that go back 2000 generations and also has an important Y chromosome marker called M45. That indicates Central Asia is where M45 originated and where both Europeans and Native Americans were descendant from. 40,000 years ago - we reach central asia
  42. 42. The Hub for migration: into europe 35,000 ya 40,000 ya
  43. 43. That marker (M45) is carried by people migrating to the Siberian arctic - ancestors of the contemporary Chukchi- nomadic reindeer herders whose entire sustenance is derived from lichen growing on the permafrost. The expedition goes to town of Ague in Siberia and travels via helicopter and converted Russian tank to Chukchi encampment 200 mi north of the arctic circle. Following the m45
  44. 44. Ò  These people live in the Arctic Circle. Ò  They herd reindeer The chukchi
  45. 45. Ò  They have smaller limbs and a shorter trunk. Ò  This structure retains heat the best. Ò  These people adapted to the extreme environment. The chukchi USARussia: home of the chukchi
  46. 46. 20,000 ya 13,000 ya 10-12,000 ya 20,000 ya, a group of their ancestors, an original tribe of perhaps 20-30 individuals journeyed across Beringia to N Alaska at the height of the ice age when temperatures got as cold (-60 below) as at any time in the human odessey. Here they settled for thousands of years trapped from further migration south by Alaskan glaciers. Around 13,000 ya as the ice age waned, a corridor opened up that allowed a small band consisting of as few as 2 males in a group of a dozen individuals to migrate south. In less than 1000 years, all of N and S America were populated by their descendants - from Inuit to Inca - with the Chukchi haplogroup marker. Into the americas
  47. 47. Ò  These people have their own stories of creation Ò  They believe that they came from the Earth Ò  They are descendents of the Chukchi people The Navajo
  48. 48. Ò  People then traveled and populated from North America all the way down to the south peak of South America. The longest journey: 50,000 years and we reach south america
  49. 49. The ~50,000 year journey to reach south america 40,000 ya 60,000 ya 20,000 ya 13,000 ya 10-12,000 ya
  50. 50. The journey 40,000 ya 60,000 ya 20,000 ya 13,000 ya 10-12,000 ya 35,000ya 40,000 ya
  51. 51. The journey
  52. 52. The journey of the ‘y’ chromosome
  53. 53. What did you learn?
  54. 54. Ò  People look different because of isolation and adaptations to different environments Ò  Underneath all of that we are the same we are all connected We are the same
  55. 55. Never forget that we share 99.9% of Our Dna with every single person On this earth
  56. 56. The Journey of Man by Spencer Wells References
  57. 57. Thank you!