Before the Dawn: Recovering the Lost History of Our Ancestors
Page 37
286 Ibid., p. 2.
287 Nicholas Wade, “Joseph Greenberg, 85, Singular Linguist, Dies,” New York Times, May 15, 2001, p. A23; Harold C. Fleming, “Joseph Harold Greenberg: A Tribute and an Appraisal,” Mother Tongue: The Journal VI:9-27(2000-2001).
288 Johanna Nichols, “Modeling Ancient Population Structures and Movement in Linguistics,” Annual Review of Anthropology, 26:359-384 (1979).
289 Mark Pagel, “Maximum-Likelihood Methods for Glottochronology and for Reconstructing Linguistic Phylogenies.”
290 Merritt Ruhlen, The Origin of Language, Wiley, 1994, p. 115.
291 Tatiana Zerjal et al., “The Genetic Legacy of the Mongols,” American Journal of Human Genetics 72:717-721 (2003).
292 ’Ala-ad-Din ’Ata-Malik Juvaini, The History of the World Conqueror, trans. J. A. Boyle, Manchester University Press, 1958, vol. 2, p. 594.
293 Nicholas Wade, “A Prolific Genghis Khan, It Seems, Helped People the World,” New York Times, February 11, 2003, p. F3.
294 Yali Xue et al., “Recent Spread of a Y-Chromosomal Lineage in Northern China and Mongolia,” American Journal of Human Genetics, 77:1112-1116 (2005).
295 George Redmonds, interview, April 5, 2000.
296 Bryan Sykes, Adam’s Curse, W. W. Norton, 2004, p. 7.
297 Bryan Sykes and Catherine Irven, “Surnames and the Y Chromosome,” American Journal of Human Genetics 66:1417-1419 (2000).
298 Nicholas Wade, “If Biology Is Ancestry, Are These People Related?” New York Times, April 9, 2000, Section 4, p. 4.
299 Bryan Sykes, Adam’s Curse, p. 18.
300 Cristian Capelli et al., “AY Chromosome Census of the British Isles,” Current Biology 13:979-984 (2003).
301 Emmeline W. Hill, Mark A. Jobling, and Daniel G. Bradley, “Y-chromosome Variation and Irish Origins,” Nature 404: 351 (2000); Nicholas Wade, “Researchers Trace Roots of Irish and Wind Up in Spain,” New York Times, March 23, 2000, p. A13; Nicholas Wade, “Y Chromosomes Sketch New Outline of British History,” New York Times, May 27, 2003, p. F2.
302 James F. Wilson et al., “Genetic Evidence for Different Male and Female Roles During Cultural Transitions in the British Isles,” Proceedings of the National Academy of Sciences 98:5078-5083 (2001).
303 Norman Davies, The Isles, Oxford University Press, 1999, p. 3.
304 Benedikt Hallgrimsson et al., “Composition of the Founding Population of Iceland: Biological Distance and Morphological Variation in Early Historic Atlantic Europe,” American Journal of Physical Anthropology 124:257-274 (2004).
305 Agnar Helgason et al., “Estimating Scandinavian and Gaelic Ancestry in the Male Settlers of Iceland,” American Journal of Human Genetics 67:697-717 (2000).
306 Agnar Helgason et al., “mtDNA and the Origin of the Icelanders: Deciphering Signals of Recent Population History,” American Journal of Human Genetics 66:999-1016 (2000).
307 Benedikt Hallgrimsson et al., “Composition of the Founding Population of Iceland.”
308 Nicholas Wade, “A Genomic Treasure Hunt May Be Striking Gold,” New York Times, June 18, 2002, p. F1.
309 Agnar Helgason et al., “A Population-wide Coalescent Analysis of Icelandic Matrilineal and Patrilineal Genealogies: Evidence for a Faster Evolutionary Rate of mtDNA Lineages than Y Chromosomes,” American Journal of Human Genetics 72:1370-1388 (2003).
310 M. F. Hammer et al., “Jewish and Middle Eastern Non-Jewish Populations Share a Common Pool of Y-chromosome Biallelic Haplotypes,” Proceedings of the National Academy of Sciences 97:6769-6774 (2000).
311 Mark G. Thomas et al., “Founding Mothers of Jewish Communities: Geographically Separated Jewish Groups Were Independently Founded by Very Few Female Ancestors,” American Journal of Human Genetics 70:1411-1420 (2002).
312 Harry Ostrer, “A Genetic Profile of Contemporary Jewish Populations,” Nature Review Genetics 2:891-898 (2001).
313 Shaye J. D. Cohen, The Beginnings of Jewishness, University of California Press, 1999, p. 303.
314 Denise Grady, “Father Doesn’t Always Know Best,” New York Times, July 7, 1988, Section 4, p. 4.
315 Yaakov Kleiman, “The DNA Chain of Tradition,” www.cohen-levi.org
316 Karl Skorecki et al., “Y Chromosomes of Jewish Priests,” Nature 385:32 (1997).
317 Israel Finkelstein and Neil Asher Silberman, The Bible Unearthed, Free Press, 2001, p. 98.
318 Mark G. Thomas et al., “Origins of Old Testament Priests,” Nature 394:138-139 (1998).
319 James S. Boster, Richard R. Hudson, and Steven J. C. Gaulin, “High Paternity Certainties of Jewish Priests,” American Anthropologist 111(4):967-971 (1999).
320 Doron M. Behar et al., “Multiple Origins of Ashkenazi Levites: Y Chromosome Evidence for Both Near Eastern and European Ancestries,” American Journal of Human Genetics 73:768-779 (2003).
321 Nicholas Wade, “Geneticists Report Finding Central Asian Link to Levites,” New York Times, September 27, 2003, p. A2.
322 Harry Ostrer, “A Genetic Profile of Contemporary Jewish Populations.”
323 Jared M. Diamond, “Jewish Lysosomes,” Nature 368:291-292 (1994).
324 Neil Risch et al., “Geographic Distribution of Disease Mutations in the Ashkenazi Jewish Population Supports Genetic Drift over Selection,” American Journal of Human Genetics 72:812-822 (2003).
325 Montgomery Slatkin, “A Population-Genetic Test of Founder Effects and Implications for Ashkenazi Jewish Diseases,” American Journal of Human Genetics 75:282-293 (2004).
326 Gregory Cochran, Jason Hardy, and Henry Harpending, “Natural History of Ashkenazi Intelligence,” Journal of Biosocial Science, in press (2005).
327 Melvin Konner, Unsettled: An Anthropology of the Jews, Viking Compass, 2003, p. 198.
328 Merrill D. Peterson, The Jefferson Image in the American Mind, Oxford University Press, 1960, p. 187.
329 Joseph J. Ellis, American Sphinx: The Character of Thomas Jefferson, Knopf, 1997.
330 Annette Gordon-Reed, Thomas Jefferson and Sally Hemings: An American Controversy, University of Virginia Press, 1997, p. 224.
331 Eugene A. Foster et al., “Jefferson Fathered Slave’s Last Child,” Nature 396:27-28 (1998).
332 Nicholas Wade, “Defenders of Jefferson Renew Attack on DNA Data Linking Him to Slave Child,” New York Times, January 7, 1999, p. A20.
333 Edward O. Wilson, Consilience, Alfred A. Knopf 1998, p. 286.
334 The Chimpanzee Sequencing and Analysis Consortium, “Initial Sequence of the Chimpanzee Genome and Comparison with the Human Genome,” Nature 436:69-87 (2005). The 99 percent agreement rests on a comparison of the human and chimp DNA sequences that directly correspond with one another. The human-chimp genome similarity falls to 96 percent after taking into account the insertions and deletions, i.e., stretches of DNA in one genome that have no counterpart in the other.
335 Louise Barrett, Robin Dunbar, and John Lycett, Human Evolutionary Psychology, Princeton University Press, 2002, p. 12.
336 Mark Pagel, in Encyclopedia of Evolution, p. 330.
337 Sarah A. Tishkoff et al., “Haplotype Diversity and Linkage Disequilibrium at Human G6PD: Recent Origin of Alleles That Confer Malarial Resistance,” Science 293: 455-462 (2001).
338 J. Claiborne Stephens et al., “Dating the Origin of the CCR5-∆32 AIDS-Resistance Allele by the Coalescence of Haplotypes,” American Journal of Human Genetics 62:1507-1515 (1998).
339 Alison P. Galvani and Montgomery Slatkin, “Evaluating Plague and Smallpox as Historical Selective Pressures for the CCR5-∆32 HIV-Resistance Allele,” Proceedings of the National Academy of Sciences, 100:15276-15279 (2003).
340 Hreinn Stefansson et al., “A Common Inversion under Selection in Europeans,” Nature Genetics 37:129-137 (2005); Nicholas Wade, “Scientists Find DNA Region That Affects Europeans’ Fertility,” New York Times, January 17, 2005, p. A12.
341 Yoav Gilad et al., “Human Specific Loss of Olfactory Receptor Genes,” Proceedings of the National Academy of Sci
ences 100:3324-3327 (2003).
342 Patrick D. Evans et al., “Microcephalin, a Gene Regulating Brain Size, Continues to Evolve Adaptively in Humans,” Science 309:1717-1720 (2005).
343 Nitzan Mekel-Bobrov et al., “Ongoing Adaptive Evolution of ASPM, a Brain Size Determinant in Homo sapiens,” Science 309:1720-1722 (2005).
344 Li Zhisui, The Private Life of Chairman Mao, Random House, 1994.
345 Quoted in Bobbi S. Low, Why Sex Matters, Princeton University Press, 2000, p. 57.
346 Elizabeth A. D. Hammock and Larry J. Young, “Microsatellite Instability Generates Diversity in Brain and Sociobehavioral Traits,” Science 308:1630-1634 (2005).
347 Richard E. Nisbett, The Geography of Thought, Free Press (2003).
348 Victor Davis Hanson, Carnage and Culture, Doubleday, 2001, p. 54.
349 Nicholas Wade, “Can It Be? The End of Evolution?” New York Times, August 24, 2003, Section 4, p. 1.
350 Bobbi S. Low, Sex, Wealth, and Fertility, in Adaptation and Human Behavior, edited by Lee Cronk, Napeoleon Chagnon and William Irons, Walter de Gruyter, 2000, p. 340.
351 The reason is that before the generation of eggs or sperm, the chromosome inherited from the mother must align itself with the counterpart chromosome inherited from the father. For the alignment to take place successfully, the DNA of the two chromosomes must match fairly well throughout their length. If the chromosomes are too diverse, with too many different DNA units, they will not pair up correctly; viable sperm or eggs will not be created and the individual will be infertile. M. A. Jobling et al., Human Evolutionary Genetics, Garland, 2004, p. 434.
352 “Harmless” is one interpretation of the Ju|’hosansi’s name for themselves, as Elizabeth Marshall Thomas notes in a new book, The Old Way. Thomas argues that their way of life was “the most successful culture that our kind has ever known,” as judged by its ecological stability and its endurance for at least 35,000 years. Her book’s vivid personal account of the !Kung’s hunter-gatherer lifestyle complements the anthropological study by Richard Borsay Lee. Elizabeth Marshall Thomas, The Old Way—A Story of the First People, Farrar Strauss Giroux, 2006.
353 Argument about which species the little Floresians should be assigned to has continued to seethe, with several researchers suggesting the skull is a pathologically small modern human. A new position, developed by researchers at the Australian National University and the University of Sydney, is that that Floresians are neither a pathological version of Homo sapiens nor a downsized version of Homeo erectus, but stem from an independent and much earlier migration out of Africa, perhaps before the island of Flores separated from the mainland. The argument is based on the skull’s similarity in brain size and other features to Homo ergaster, the predecessor of erectus. Debbie Argue, Denise Donlon, Colin Groves, and Richard Wright, “Homo floresiensis: Microcephalic, pygmoid, Australopithecus, or Homo?,” Journal of Human Evolution 51, 360-374 (2006).
354 The roots of the Aurignacian culture are still obscure. If modern humans reached Europe from India, as seems likely from the genetic evidence, signs of predecessor culture might be expected in the Indian subcontinent. But so far the archaeological evidence from India shows little evidence of the sophisticated behaviors possessed by the Aurignacians. (Hannah V. A. James and Michael D. Petraglia, “Modern Human Origins and the Evolution of Behavior in the Later Pleistocence Record of South Asia,” Current Anthropology; 46 [Supplement]: 3-27 [2005].) Possibly the elements of the Aurignacian culture were formed at some point during the migration from India to Europe, as the first modern humans adapted from a subtropical climate to that of the European ice age.
355 An important revision in radiocarbon dating indicates an earlier and much compressed time scale for the Aurignacians’ spread across Europe. The revision was prompted by a) a new method of filtering out contaminants that have made ancient carbon sources seem younger than they were, and b) a new estimate of the amount of carbon-14 in the atmosphere in the distant part. With these two refinements, Paul Mellars has now revised his timetable for the arrival of modern humans in Europe. He estimates that they had arrived west of the Black Sea by 46,000 years ago, not 40,000-44,000 years ago as shown in Fig. 5.2, and had reached northern Spain by 41,000 years ago, not 36,000 years ago. Mellars argues that the Neanderthal fossils from the Zafarraya cave in Spain and Vindija in Croatia, both at present dated to about 30,000 years ago, will turn out to be much older. If so, the new timetable indicates that the Neanderthals succumbed much more quickly than had been supposed, perhaps in a mere 5,000 years. The moderns’ rapid advance may have been helped by an improvement in climatic conditions that occurred between 43,000 and 41,000 years ago. Paul Mellars, “A New Radiocarbon Revolution and the Dispersal of Modern Humans in Eurasia,” Nature 439:931-935, 2006.
356 Lahn’s two microcephalin genes did not show up in a genomewide search for recently selected genes performed by Jonathan Pritchard and colleagues (see note 363). That may reflect limitations of the Pritchard test, no test for selection being perfect. Pritchard did detect signals of selection in two other genes involved in microcephaly, and in several other types of brain gene. Some of these brain genes were under selection in Africans, some in Asians, and some in Europeans, confirming Lahn’s view that cognitive evolution may have proceeded independently in the three populations. Many of the genetic changes occurring independently in the major continental races are likely to have been convergent, meaning that evolution was using the different mutations available to it in each population to bring about the same adaptation.
357 A new refinement of the radiocarbon dating method (see note 355 above) indicates the drawings of the Chauvet cave as much older than supposed. The first occupation can now be dated to 36,000 years ago.
358 Increasing evidence suggests that pale skin, a variation on the dark skin of the ancestral human population, arose independently in the populations of west and east Eurasia, even though the cause—adapting to the reduced sunlight of northern latitudes—was presumably the same in both cases. Five genes affecting skin color show signs of recent selection in Europeans but not in East Asians. (See notes 230 and 363.) This implies either that East Asians acquired their pale skin through changes in a different set of genes or that their skins became pale considerably earlier than did those of Europeans. In the latter case, the signs of selection would have faded and the genes in East Asians would not have been flagged by Pritchard’s test.
359 Most people in Africa and Europe have wet earwax. But dry earwax is the rule among East Asians. A team of Japanese researchers has traced the difference to a mutation in a gene called ABCC11. (Koh-ichiro Yoshiura et al., “A SNP in the ABCC11 Gene Is the Determinant of Human Earwax Type,” Nature Genetics, 38:324-330 [2006].) The mutation seems to have arisen in the northern part of east Asia and to have become common very quickly—it is almost universal in northern Han Chinese and in Koreans. What selection pressure made the new version of the gene spread so rapidly? Earwax serves the very humble role of biological flypaper—it stops insects and dirt from getting into the ear—and a change in earwax consistency seems unlikely to have been much of an advantage. The new gene was probably selected because it seems also to reduce the amount of sweating, and hence of body odor. One or the other quality, or both, may have given the gene its decisive advantage.
360 However, the horse Y chromosome is telling a possibly different story. Unlike the mitochondrial DNA, samples of a small region of the Y chromosome from 15 different breeds of European and Asian horses proved to be identical. Gabriella Lindgren et al., “Limited Number of Patrilines in Horse Domestication,” Nature Genetics, 36:335-336 (2004). This indicates that ancient horse breeders, like modern ones, often let a single stallion cover many females. It could also allow for the possibility that independent do mestications of the horse were not as common as the mitochondrial DNA evidence suggests.
361 This assumption has been confirmed by a direct study of the first Neolithic farmers to settle in Europe.
Mitochondrial DNA was extracted from bones taken from archaeological sites of the earliest farming communities of 7,500 years ago in Germany, Austria, and Hungary. A quarter of the sample belonged to the N1a subbranch of the mitochondrial tree, a type that is now very rare among Europeans. This implies that though Neolithic farming techniques spread rapidly, the farmers themselves did not make much of a genetic impact. The authors favor the possibility “that small pioneer groups carried farming into new areas of Europe, and that once the technique had taken root, the surrounding hunter-gatherers adopted the new culture and then outnumbered the original farmers, diluting their N1a frequency to the low modern value.” Wolfgang Haak et al., “Ancient DNA from the First European Farmers in 7500-Year-Old Neolithic Sites,” Science, 310: 1016-1018 (2005).
362 I thank a reader, the food writer Anne Mendelson, for pointing out that in many parts of the world milk is consumed only in sour form, such as yoghurt, after its lactose has been converted by bacteria into lactic acid. In such conditions there would be no pressure for lactose tolerance to evolve. Nonetheless, lactose tolerance did arise, so presumably the people of the Funnel Beaker culture must have consumed milk in raw form, perhaps not knowing how to ferment it.