Race and Human Evolution:
A Fatal Attraction
by Milford H. Wolpoff
and Rachel CaspariRace and Human Evolution:
A Fatal Attraction
by Milford H. Wolpoff
and Rachel Caspari
Posted on 09/05/2001 5:05:20 PM PDT by sarcasm
Part 1: The debate
Over recent years, there has been a loud debate within palaeoanthropology over the origins of anatomically modern humans, or AMH. Opinions have polarized into two camps: Multiregional Evolution, or MRE, and Out-of-Africa, or OOA.
The former group of anthropologists, including Milford Wolpoff and Loring Brace, argue that ever since members of the genus Homo first spread out of Africa, probably before 1 million years ago (mya), we have all been members of one species. The many different populations of humans were all subject to natural selection, and gradually evolved along similar lines.
These different populations may have passed through different grades, so that at 1.0 mya they were all Homo erectus, while at 0.5 mya they were all Homo sapiens. But they never divided into two or more species because there was always sufficient gene flow across Eurasia to maintain genetic continuity.
The latter group, including vocal proponents Chris Stringer and Ian Tattersall, argue that all living humans are descended from an African population that lived within the last 200 thousand years (kya). They argue that earlier, non-African hominids belong to distinct species, such as Homo neanderthalensis, and that they have left no trace in the modern gene pool.
In Europe, in particular, OOA supporters see a strong discontinuity between Neanderthals and AMH. They believe that the physical and cultural differences between the two, and their apparent coexistence for several millennia, are evidence for a species-level distinction. Neanderthals were out-competed and replaced by moderns. Some even believe that there may have been genocidal warfare between the two.
In both Europe and Asia, MRE supporters point to evidence for continuity in particular morphological traits from earlier populations to later ones. They agree that modern Europeans do not look particularly similar to Neanderthals, but believe that they appear more so than non-Europeans do. Similarly, they see persistence of other skeletal traits from Javan Homo erectus through modern Australian Aborigines.
Some anthropologists take an intermediate position, arguing that there was a population movement out of Africa but that these migrants interbred with older local populations. They see the intermediate morphology of skeletons such as Lagar Velho 1 as a sign of hybridization.
Single origin supporters see the same remains (primarily skulls) differently. They argue that there are no clear regional continuities, and that any that do exist can be explained by parallel adaptation to the same environment. Instead, they see all AMH skeletal remains as fundamentally similar to those found in sub-Saharan Africa at sites such as Klasies River Mouth at 120 kya.
Genetic evidence has slowly mounted to support the OOA case. Humans exhibit far less genetic variation than any of our cousins do, despite our visible differences in phenotype. This indicates shared recent ancestry, and many estimates have placed that ancestry after 200 kya. But any reconstruction based purely on modern genetic variation is just that, a reconstruction, and does not prove that all of our common ancestry is that recent.
Recently, mitochondrial DNA from three Neanderthal specimens has been analyzed. The three individuals were all quite distinct from all known modern sequences, which provided support for their non-ancestral status. Judging from the popular press, these studies were the final nail in MRE's coffin.
That tone changed dramatically last week, when news stories appeared about two different studies that counter the genetic and skeletal evidence for OOA. While neither of these studies proves MRE to be true, they suggest that the actual picture is far more complicated than many OOA supporters admit.
Part 2: New evidence
The first study appears this week in the Proceedings of the National Academy of Sciences. Gregory Adcock and colleagues present mtDNA sequences from ten ancient Australian skeletons. Six of these individuals are very robust morphologically and come from Kow Swamp, dating to 8-15 kya, and three are more gracile and date to sometime after 10 kya. The tenth, Lake Mungo 3, is also gracile, and is significantly older than the others. The authors accept a date that has been proposed elsewhere of 62,000 kya; others argue that 20 kya is more accurate.
The gracile skeletons are well within the range of variation of contemporary Australian Aborigines. The robust individuals are not, and some anthropologists have previously argued that the two groups represent two different ancient migrations to the continent, whose descendants fused into modern Aborigines. Others have disputed this model, arguing that the apparent variation is the result of sexual dimorphism, poor preservation, pathology, and inadequate dating. The mtDNA samples from the two groups could not be distinguished from each other or from modern Aboriginal samples, which supports either argument. All samples fit within the broader pattern of modern mtDNA variation that has been taken to support the OOA model.
All, that is, save Lake Mungo 3, the oldest of the skeletons (whether or not one accepts 60 kya). The mtDNA from this individual is distinct from that of all living humans. It is not as distinct as the three Neanderthal sequences, but it clearly can trace its ancestry back well beyond the other known modern haplotypes. Genetically, it is highly unlikely that the maternal ancestry of this individual can be traced back to Africa within the past 200,000 years.
What does this mean? Despite some press reports, it does not mean that we are all descended from Australians. It does mean that not all anatomically modern humans can trace their ancestry to a recent African origin. If an individual who is morpologically indistinguishable from modern Australians has an extinct mtDNA haplotype, other individuals with extinct haplotypes, like the Neanderthals, cannot be excluded from modern human ancestry on mtDNA grounds alone.
On a broader scale, it suggests that the limited variation in modern human mtDNA may be the result of either genetic drift, which over time has caused other mtDNA lineages to go extinct, or natural selection in favor of one particular type of mtDNA for some unknown reason. In either case, modern mtDNA variation does not necessarily tell us a thing about ancient population history.
The second study appeared last Friday in Science. In it, Milford Wolpoff and colleages examined the morphology of one early skull from Australia, Willandra Lakes 50, and two from Mladec, Czech Republic. These are some of the earliest and most complete skulls that everyone agrees are anatomically modern.
They compared these skulls to those which MRE and OOA supporters might consider ancestral to them: The Australian skull to crania from Ngandong, Java, and a variety of sites in the Near East and Africa, and the Mladec skulls to European Neanderthals as well as male crania from Qafzeh and Skhul in Israel. If the replacement model is true, then WLH-50 should be more similar to the Levantine and African specimens than to those from Ngandong, while the Mladec crania should be more similar to Skhul and Qafzeh than to classic Neanderthals.
To perform these comparisons they scored 16 non-metric traits on WLH-50 and 30 on Mladec, and compared presence/absence of each trait to each other skull. They found that WLH-50 was more similar to 6 of the 7 Ngandong skulls than it was to any from Africa or the Near East. Mladec 5 was most similar to three Near Eastern skulls, but Mladec 6 was more akin to the Neanderthals.
Although the sample sizes of both individuals and traits were small, statistical tests indicated that the recent African origin hypothesis was not proven. That is, from this data the more recent anatomically modern humans were no more closely related to earlier "AMH" specimens than they were to "archaic" specimens, whether Neanderthal or Javan.
The conclusion that these two studies most clearly point to is that the complete replacement theory is probably an overstatement. Reality was a bit messier. Yes, there may have been extensive gene flow out of Africa within the past 100,000 years. But this was not the expansion of a genocidal new species. Different regions had their own population histories: In some areas, earlier populations may well have left no descendants, while in other places, resident and immigrant populations did mix.
They also highlight how little we still know about the process. Morphological and genetic studies of more well dated fossils from throughout the Old World are needed before we can pin down the details of the transformation to modernity.
The Highlander's (im)mortal enemy was a kurgan...
The truth hurts, IF you are an evolutionist!
The only problem is that non-evolutionists always confuse "more-evolved" with "better". Suppose it can be demonstrated through mtDNA that a typical Eskimo is more "evolved" than a typical Ethiopian. Only an idiot would conclude that an Eskimo is "better" than an Ethiopian when placed side-by-side, away from either one's natural habitat - say, in New Jersey. The Ethiopian is superior to the Eskimo in dealing with the dry North African climate, and the Eskimo is clearly superior in dealing with the Arctic chill.
Evolved/Better...don't confuse the two, and don't forget Environmental Context - in evolutionary circles, it's the main point.
Please FREEPMAIL me if you want on, off, or alter the "Gods, Graves, Glyphs" PING list --
Archaeology/Anthropology/Ancient Cultures/Artifacts/Antiquities, etc.
The GGG Digest -- Gods, Graves, Glyphs (alpha order)
I researched this whole argument extensively as preparation for my Masters thesis regarding the origins of language in hominids. I can argue this point AT LENGTH -- in fact, at such a length that you will just want me to go away, OKAY?
But I would just like to state that Wolpoff has been thoroughly discredited amongst his peer community, and that there is nothing new about this. Wolpoff has been getting discredited for the past couple of decades, yet he persists. Ain't tenure wonderful?
The books I've read on the subject suggest that the genetic evidence is overwhelming for OOA and morphology is proving to be weaker evidence than claimed, the Lagar Velho 1 child has been identified as modern human.
Unless Wolpoff et al have something stronger, it seems they're spitting into the wind.
dang blam
you cut off the article you posted just as they were about to post the words with the commen meaning and pronunciation that date to early iron age in the indo european language.
please post the url for that so I can read the rest of the story.
my guess for proto european words? "cat" and "hat" but not "the" "came" or "back"
Sorry, I don't know where I got this from.
Race and Human Evolution:
A Fatal Attraction
by Milford H. Wolpoff
and Rachel CaspariRace and Human Evolution:
A Fatal Attraction
by Milford H. Wolpoff
and Rachel Caspari
|
|
|||
Gods |
Just updating the GGG info, not sending a general distribution. |
||
|
· Discover · Nat Geographic · Texas AM Anthro News · Yahoo Anthro & Archaeo · Google · · The Archaeology Channel · Excerpt, or Link only? · cgk's list of ping lists · |
|||
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.
