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to prove； or disprove； from fossils。 in 1999； archeologists in portugal found theskeleton of a child about four years old that died 24；500 years ago。 the skeleton was modernoverall； but with certain archaic； possibly neandertal； characteristics： unusually sturdy legbones； teeth bearing a distinctive “shoveling” pattern； and （though not everyone agrees on it）an indentation at the back of the skull called a suprainiac fossa； a feature exclusive toneandertals。 erik trinkaus of washington university in st。 louis； the leading authority onneandertals； announced the child to be a hybrid： proof that modern humans and neandertalsinterbred。 others； however； were troubled that the neandertal and modern features weren’tmore blended。 as one critic put it： “if you look at a mule； you don’t have the front endlooking like a donkey and the back end looking like a horse。”
ian tattersall declared it to be nothing more than “a chunky modern child。” he accepts thatthere may well have been some “hanky…panky” between neandertals and moderns； butdoesn’t believe it could have resulted in reproductively successful offspring。
1“i don’t knowof any two organisms from any realm of biology that are that different and still in the samespecies；” he says。
with the fossil record so unhelpful； scientists have turned increasingly to genetic studies；in particular the part known as mitochondrial dna。 mitochondrial dna was only discoveredin 1964； but by the 1980s some ingenious souls at the university of california at berkeley hadrealized that it has two features that lend it a particular convenience as a kind of molecularclock： it is passed on only through the female line； so it doesn’t bee scrambled withpaternal dna with each new generation； and it mutates about twenty times faster than normalnuclear dna； making it easier to detect and follow genetic patterns over time。 by tracking therates of mutation they could work out the genetic history and relationships of whole groups ofpeople。
in 1987； the berkeley team； led by the late allan wilson； did an analysis of mitochondrialdna from 147 individuals and declared that the rise of anatomically modern humansoccurred in africa within the last 140；000 years and that “all present…day humans aredescended from that population。” it was a serious blow to the multiregionalists。 but thenpeople began to look a little more closely at the data。 one of the most extraordinary points—almost too extraordinary to credit really—was that the “africans” used in the study wereactually african…americans； whose genes had obviously been subjected to considerablemediation in the past few hundred years。 doubts also soon emerged about the assumed ratesof mutations。
by 1992； the study was largely discredited。 but the techniques of genetic analysiscontinued to be refined； and in 1997 scientists from the university of munich managed toextract and analyze some dna from the arm bone of the original neandertal man； and thistime the evidence stood up。 the munich study found that the neandertal dna was unlike anydna found on earth now； strongly indicating that there was no genetic connection betweenneandertals and modern humans。 now this really was a blow to multiregionalism。
1one possibility is that neandertals and cro…magnons had different numbers of chromosomes； a plicationthat monly arises when species that are close but not quite identical conjoin。 in the equine world； forexample； horses have 64 chromosomes and donkeys 62。 mate the two and you get an offspring with areproductively useless number of chromosomes； 63。 you have； in short； a sterile mule。
then in late 2000 nature and other publications reported on a swedish study of themitochondrial dna of fifty…three people； which suggested that all modern humans emergedfrom africa within the past 100；000 years and came from a breeding stock of no more than10；000 individuals。 soon afterward； eric lander； director of the whiteheadinstitute/massachusetts institute of technology center for genome research； announced thatmodern europeans； and perhaps people farther afield； are descended from “no more than afew hundred africans who left their homeland as recently as 25；000 years ago。”
as we have noted elsewhere in the book； modern human beings show remarkably littlegenetic variability—“there’s more diversity in one social group of fifty…five chimps than inthe entire human population；” as one authority has put it—and this would explain why。
because we are recently descended from a small founding population； there hasn’t been timeenough or people enough to provide a source of great variability。 it seemed a pretty severeblow to multiregionalism。 “after this；” a penn state academic told the washington post；“people won’t be too concerned about the multiregional theory； which has very littleevidence。”
but all of this overlooked the more or less infinite capacity for surprise offered by theancient mungo people of western new south wales。 in early 2001； thorne and his colleaguesat the australian national university reported that they had recovered dna from the oldest ofthe mungo specimens—now dated at 62；000 years—and that this dna proved to be“genetically distinct。”
the mungo man； according to these findings； was anatomically modern—just like you andme—but carried an extinct genetic lineage。 his mitochondrial dna is no longer found inliving humans； as it should be if； like all other modern people； he was descended from peoplewho left africa in the recent past。
“it turned everything upside down again；” says thorne with undisguised delight。
then other even more curious anomalies began to turn up。 rosalind harding； a populationgeneticist at the institute of biological anthropology in oxford； while studying betaglobingenes in modern people； found two variants that are mon among asians and theindigenous people of australia； but hardly exist in africa。 the variant genes； she is certain；arose more than 200；000 years ago not in africa； but in east asia—long before modern homosapiens reached the region。 the only way to account for them is to say that ancestors ofpeople now living in asia included archaic hominids—java man and the like。 inte