1。8 liters for neandertals versus 1。4 formodern people； according to one calculation。 this is more than the difference between modern homo sapiens and late homo erectus ； a species we are happy to regard as barelyhuman。 the argument put forward is that although our brains were smaller； they weresomehow more efficient。 i believe i speak the truth when i observe that nowhere else inhuman evolution is such an argument made。
so why then； you may well ask； if the neandertals were so stout and adaptable andcerebrally well endowed； are they no longer with us？ one possible （but much disputed）answer is that perhaps they are。 alan thorne is one of the leading proponents of an alternativetheory； known as the multiregional hypothesis； which holds that human evolution has beencontinuous鈥攖hat just as australopithecines evolved into homo habilis and homoheidelbergensis became over time homo neanderthalensis； so modernhomo sapiens simplyemerged from more ancient homo forms。homo erectus is； on this view； not a separate speciesbut just a transitional phase。 thus modern chinese are descended from ancient homo erectusforebears in china； modern europeans from ancient european homo erectus； and so on。
鈥渆xcept that for me there are no homo erectus；鈥潯ays thorne。 鈥渋 think it鈥檚 a term which hasoutlived its usefulness。 for me； homo erectus is simply an earlier part of us。 i believe onlyone species of humans has ever left africa； and that species ishomo sapiens。鈥�
opponents of the multiregional theory reject it； in the first instance； on the grounds that itrequires an improbable amount of parallel evolution by hominids throughout the old world鈥攊n africa； china； europe； the most distant islands of indonesia； wherever they appeared。 somealso believe that multiregionalism encourages a racist view that anthropology took a very longtime to rid itself of。 in the early 1960s； a famous anthropologist named carleton coon of theuniversity of pennsylvania suggested that some modern races have different sources oforigin； implying that some of us e from more superior stock than others。 this hearkenedback unfortably to earlier beliefs that some modern races such as the african 鈥渂ushmen鈥�
（properly the kalahari san） and australian aborigines were more primitive than others。
whatever coon may personally have felt； the implication for many people was that someraces are inherently more advanced； and that some humans could essentially constitutedifferent species。 the view； so instinctively offensive now； was widely popularized in manyrespectable places until fairly recent times。 i have before me a popular book published bytime…life publications in 1961 called the epic of man based on a series of articles in lifemagazine。 in it you can find such ments as 鈥渞hodesian man 。 。 。 lived as recently as25；000 years ago and may have been an ancestor of the african negroes。 his brain size wasclose to that of homo sapiens。鈥潯n other words black africans were recently descended fromcreatures that were only 鈥渃lose鈥潯o homo sapiens。
thorne emphatically （and i believe sincerely） dismisses the idea that his theory is in anymeasure racist and accounts for the uniformity of human evolution by suggesting that therewas a lot of movement back and forth between cultures and regions。 鈥渢here鈥檚 no reason tosuppose that people only went in one direction；鈥潯e says。 鈥減eople were moving all over theplace； and where they met they almost certainly shared genetic material throughinterbreeding。 new arrivals didn鈥檛 replace the indigenous populations； they joined them。 theybecame them。鈥潯e likens the situation to when explorers like cook or magellan encounteredremote peoples for the first time。 鈥渢hey weren鈥檛 meetings of different species； but of the samespecies with some physical differences。鈥�
what you actually see in the fossil record； thorne insists； is a smooth； continuoustransition。 鈥渢here鈥檚 a famous skull from petralona in greece； dating from about 300；000 yearsago； that has been a matter of contention among traditionalists because it seems in some ways homo erectus but in other ways homo sapiens。 well； what we say is that this is just what youwould expect to find in species that were evolving rather than being displaced。鈥�
one thing that would help to resolve matters would be evidence of interbreeding； but that isnot at all easy 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 鈥渟hoveling鈥潯attern； 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鈥檛more blended。 as one critic put it： 鈥渋f you look at a mule； you don鈥檛 have the front endlooking like a donkey and the back end looking like a horse。鈥�
ian tattersall declared it to be nothing more than 鈥渁 chunky modern child。鈥潯e accepts thatthere may well have been some 鈥渉anky…panky鈥潯etween neandertals and moderns； butdoesn鈥檛 believe it could have resulted in reproductively successful offspring。
1鈥渋 don鈥檛 knowof any two organisms from any realm of biology that are that different and still in the samespecies；鈥潯e 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鈥檛 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 鈥渁ll present…day humans aredescended from that population。鈥潯t 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鈥攁lmost too extraordinary to credit really鈥攚as that the 鈥渁fricans鈥潯sed 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 鈥渘o more than afew hundred africans who left their homeland as recently as 25；000 years ago。鈥�
as we have noted elsewhere in the book； modern human beings show remarkably littlegenetic variability鈥斺�渢here鈥檚 more diversity in one social group of fifty…five chimps than inthe entire human population；鈥潯s one authority has put it鈥攁nd this would explain why。
because we are recently descended from a small founding population； there hasn鈥檛 been timeenough or people enough to provide a source of great variability。 it seemed a pretty severeblow to multiregionalism。 鈥渁fter this；鈥潯 penn state academic told the washington post；鈥減eople won鈥檛 be too concerned about the multiregional theory； which has very littleevidence。鈥�
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鈥攏ow dated at 62；000 years鈥攁nd that this dna proved to be鈥済enetically distinct。鈥�
the mungo man； according to these findings； was anatomically modern鈥攋ust like you andme鈥攂ut 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。
鈥渋t turned everything upside down again；鈥潯ays 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 thei