Tag Archives: genetics

Pathological Science and mtEve

While reading The Disappearing Spoon by Sam Kean, the author discussed the concept of ‘pathological science.’  ‘Pathological science’ results from scientists who cling to their ideas even when there is plenty of evidence against them.  For instance, Kean discusses the idea that megalodon sharks might still be circling the deep oceans even though there is no evidence for this, while there is evidence that those sharks died out at least one million years ago.  Yet, some scientists are pathologically attached to the idea that the megalodon lives.

I realized that ‘pathological science’ was the perfect term to describe what happened over the past 25 years with the rise of mtEve and the demotion of Neanderthals to non-H. sapiens status.  There was/is little evidence to support mtEve as a concept, but it so excited many otherwise respectable scientists, not to mention the media and the general public, that mtEve swept away anyone who disagreed that she was the mother of all modern humans.  This was a pathological science creation event par excellence. If this non-existent entity had been named mtMable, the rush to embrace her probably would not have occurred.

The name ‘mtEve’ fed into the creation stories many scientists were raised with; even if they no longer believed the stories, the concepts still manifested at an unconscious level. For the media and the general public who did/do still believe these creation stories, mtEve provided immediate validation that humans were special.  Humans were not just another animal; not just another result of evolution.  Pathological scientists also want ‘modern’ humans to be viewed as special, distinct, better than any preceding humans who were ‘archaic’ and different, more like an animal, less intelligent.  Given the location of mtEve (Africa) and the poorly-derived date of mtEve (it varies a great deal, but many use 250,000 years ago), Neanderthals were relegated to the ‘archaic’ heap.

I have spent the past two-plus decades fighting against this pathological science, only to see it become accepted dogma even in textbooks. This is disturbing. If scientists can be so swept away by their emotions that they totally ignore evidence, is it any wonder that respect for science is softening?  Fortunately, science is eventually self-correcting. It’s taken too long, but it is finally becoming clear that Neanderthals were no less ‘modern’ than so-called ‘moderns.’  There was no creation event 250,000 years ago in which mtEve popped into being and begat the first modern human.  For 25 years, I asked for evidence of how speciation occurred between ‘archaics’ and ‘moderns’ and was shown no evidence.  I was not surprised since there was and is no such evidence: mtEve was a creation of pathological science.

Robert G. Bednarik’s chapter, “The Expulsion of Eve” in his book The Human Condition, is a precise and detailed refutation of mtEve and the concept of ‘modern’ and ‘archaic’ humans. He slices and dices the ‘evidence’ (morphological, genetic, lithic, and cultural) until there is nothing left but hot air.  While Bednarik does not use the term ‘pathological science’, it is clear from his analysis that mtEve proponents were and are acting pathologically.  “…the Eve supporters have led the study of hominin origins on a monumental wild-goose chase.”


	

DNA and Race

I just finished reading DNA USA: A Genetic Portrait of America by Bryan Sykes.  This is a very odd book.  I was expecting to read a major genetic analysis of population diversity in the US.  Instead, it is more a travel log of Sykes’ tour of American landmarks with a few, essentially random, meetings with individuals where their DNA was collected for analysis. This analysis is discussed in one, relatively brief, concluding chapter. The topic of the book was more genealogical than genetic.

It seems that Sykes may have been hoping to write a book about the US similar to those Bill Bryson has written about Britain and Australia.  DNA USA somewhat resembles Bryson’s book on Australia: In a Sunburned Country, but Sykes does not have Bryson’s comedic flare nor verbal virtuosity.

Having said that, once I got past the fact that the book was not what I expected, I did enjoy reading it, perhaps because I have been to most of the places Sykes visited. In addition, I am interested in the ways in which genetics can inform, but also misinform (or, more precisely, under-inform) genealogy.

Sykes is a geneticist who uses mtDNA (passed through the maternal line) and Y chromosome (passed through the paternal line) to tie genetic information to the past. Soon after he began this research, he began to be inundated with requests from the general public to have their DNA analyzed.  Sykes made the decision to create a business, Oxford Ancestors, designed to meet this need. A similar business model, African Ancestry, was set up in the US by Rick Kittles and Gina Paige.

While some interesting genetic information can be obtained from these methods, vast amounts of information are unavailable.  To simplify this, think about a woman who has one or more sons, but no daughters.  Her mtDNA will not show up in her grandchildren since the only material passed from the sperm to the egg is the nuclear DNA (nDNA), not any mtDNA.  If her granddaughter has her mtDNA analyzed, the granddaughter will learn about her mother’s genetic line, but nothing about her paternal grandmother’s line.  The grandson can learn about his paternal grandfather’s line (along with his maternal line), but, again, nothing about his paternal grandmother’s line.  A huge chunk of genetic knowledge is unavailable by these methods. Not to mention that the actual amount of genetic information in mtDNA and the Y chromosome is extremely tiny compared to nDNA. Making broad statements about anyone’s ancestry when so much information is missing is, at the least, highly problematic.  Yet, that is exactly what genetics researchers using these two methods claim.  These claims even extend to human origins. I don’t wish to get into that topic more deeply in this blog post.  However, given what I’ve just written, I hope readers will apply great caution towards accepting claims about human origins made on such limited mtDNA and Y chromosome data.

For his American odyssey, Sykes decided to use a new, more informative genetic analysis developed by the company 23andMe. As described by Sykes, 23andMe uses nDNA and creates a colored portrait of an individual’s 22 autosomal chromosomes.  Prior nDNA researchers who analyzed the DNA of individuals from many different countries found genetic variants that are associated with particular groups.  For ease of analysis, these variants were lumped into three continental groups: Asian, European, and African.  For the purposes of analysis in the US, Asian is a proxy for Native American since genetic research has shown that these groups have a common origin. This method accesses information from both parents while also giving information on specific genes that have been identified on each chromosome.  In these respects, tying genetics to genealogy is more effective and complete than is the case with mtDNA or Y chromosome analyses. However, it is still incomplete.

The image below shows the process of genetic recombination during meiosis.  The orange and green represent one chromosome pair from the man while the pink and blue represent the same chromosome pair from the woman.  During meiosis, the chromosomes make a copy of themselves.  These copies line up close enough that chunks of DNA can be exchanged between the chromosomes.  Upon completion of meiosis, one chromosome each ends up in the sperm and egg.  These chromosomes passed on to their child represent only a small fraction of the DNA diversity in the parents.  As this process occurs in each generation, huge amounts of genetic information are lost over the generations.  If solid-color chromosomes were the ones in the egg and sperm, all genetic information for that chromosome from one paternal and one maternal grandparent would be lost in the child. Therefore, while nDNA is better for analyzing genetic history, it is by no means a complete picture of an individual’s genealogy.

Given these caveats, the method used by 23andMe does provide a great deal of useful information that is presented in the visually appealing format of chromosome painting. It is in the final chapter describing the genetic ‘portraits’ of the few individuals from whom Sykes obtained DNA that he makes observations that are particularly relevant to the subject of whether or not race is biological.  You might think that Sykes would support the idea of biological races given that these genetic methods divide the world into three groups: Asian/Native American, European, and African.  But Sykes recognizes that these are over-simplifications of actual diversity and views them more as geographical, rather than biological entities.

Americans are especially revealing in that most of them display genetic diversity rather than uniformity.  The only individuals Sykes analyzed that did not display diversity were the members of a genealogical society in Boston who could trace their ancestry in America back to the 17th and 18th centuries.  He found this quite surprising and concluded that any of their ancestors who inter-married with Native Americans became part of those cultural groups rather than the European-descent cultural group.  This is supported by the genetic analysis of individuals of Northeast Native American ancestry whose chromosome analyses show their genes to be almost entirely European derived.  European Americans with Southern ancestry showed some genetic evidence of African ancestry, while all African Americans showed European and Native American ancestry, although the percentages differed widely.  Sykes concluded that “…many whites with deep roots in the South have some black ancestors.” (p.313)  He mentions that he would like to have analyzed the DNA of a Ku Klux Klan member because he is pretty sure it would have sections indicating genes with African ancestry.  It would have been interesting to find out how that individual reacted to this knowledge.

Sykes notes that assuming because of someone’s appearance and/or culture that you can draw any conclusions about their genetics and health concerns demonstrates a lack of knowledge of the complexity of genetic inheritance.  As an example, Sykes points out that he has African ancestry for the tip of chromosome 11 while one of the African-American men he analyzed has European ancestry for that same region.  As this region includes the genes for beta-globin, Sykes states, contrary to what most physicians would conclude, that he, Sykes, could be a carrier for sickle cell anemia while the other man could not.

Another gene that showed diversity was P450 cytochromes found on chromosome 10.  This gene produces proteins which help to clear drugs and toxins from the liver.  Medical researchers have found that an African-derived form of the gene is less effective.  This led to different, lower dosing recommendations of drugs such as beta-blockers for African Americans.  However, since Americans have diverse genetic ancestry, simply assuming an individual African American should have a lower dose than an individual European American can lead to major errors.  Sykes states, “…that of my nine African American volunteers, only three have both copies of their P450 gene from African ancestors, three have one European and one African copy, and the genes of the remaining three are completely European.”  On the other hand, one of his southern European-American volunteers had the African form of the gene.  Racially categorizing these individuals would lead to medical errors.

The conclusion I draw from this book is one I have long held. Racial categories have little meaning whether they are assumed to be cultural or biological because genetics and culture have no necessary overlap.

 

 

Is racism OK if the group is extinct?

Along with some of my physical anthropology students, I attended a public lecture on the Neanderthal genome given by one of the men who worked on the genome.  An issue my students and I hoped the speaker would clarify is whether he considered Neanderthals a different species even though he admitted that EurAsians had some Neanderthal genes.

When one of my students asked about this, he stated that it was obvious they were a different species.  “Look at my graph! It’s obvious!”  However, it was not obvious.  His graph compared the DNA (presumably nDNA rather than mtDNA, but he was unclear on this) of three Neanderthal females from the site of Vindija, Croatia, to the DNA of multiple individuals from different 21st century populations.  There was a bit of a deviation of the Neanderthal lines from the non-Neanderthal lines, but the trend of the lines was the same. To further support his contention of different species, he said it was obvious from a comparison of the skulls of the two “species”.  He then showed a comparison of a La Ferrassie Neanderthal with a current European skull. This same student said that differences were not obvious when comparing skulls from around the same time period that belonged to Neanderthal and so-called moderns.  The speaker then began a jargon-dense explanation of a skull analysis technique that he felt proved his point.  I let this slide because of the type of audience present, but I did e-mail the speaker after the talk.  In that e-mail I noted that I’d been at conferences where one speaker using the technique he described ‘proved’ Neanderthals were a different species based on skull morphology, while the very next speaker, using the same technique and skulls, came to the conclusion that Neanderthals fell within modern human variation, and so were the same species as we are.  He didn’t respond to this.

Back at the talk, another of my students asked the speaker how he could be so sure of his conclusions when he had only three samples and they all came from the same site; and, further, had not been compared to ‘moderns’ from the same time period.  The speaker’s answer to this was not really clear, but seemed to be “Look at my graph! It’s obvious!”   I also asked him about this in my e-mail. He responded that he saw no point in comparing to “moderns.”  His comment: “We know that most of the DNA variation present within currently living humans dates back, on average, hundreds of thousands of years. Therefore, there is little to be learned from sequencing early modern humans. Nevertheless, this is being done anyway. In fact, there was a paper in Science last week
(http://www.sciencemag.org/content/336/6080/466.full) with DNA from several Neolithic humans. Unsurprisingly, they differ little from currently living humans.”

I replied that Neolithic humans lived thousands of years after Neanderthals (the time period in the article was about 5000 years ago) and were in the midst of one of the most severe selection events to affect humans due to the rise of contagious infectious disease among early agricultural populations, along with impaired nutrition due to restricted diets.  As we are still living in this changed environment of infectious disease and poor nutrition, it is not too surprising that “they differ little from currently living humans.”  Nor would it be surprising if they differed somewhat from Neanderthals, although that analysis was not done. However, the article does not really appear to support his point anyway.  Four individuals were tested: three northern European hunter/gatherers and one farmer who appeared related to southern Europeans. What this article points to is that, as with the Neanderthal genome, a tiny sample is used to make huge generalizations.

To enforce his point during his talk that Neanderthals were a different species, he implied that they were stupider than ‘moderns’ by comparing Mousterian tools of 150,000 years ago to cave art of 30,000 years ago.  In my e-mail, I reminded him of that fact that Neanderthals of 40,000 years ago were using Upper Paleolithic tools, and that the 10,000 years from 40,000 to 30,000 years ago is an extremely long time.  My comments were:

“Think how much our culture has changed in the past 10,000 years.  But even if you do not like that comparison, what about the Tasmanians who were isolated from the rest of the world for 10,000 years until found by Captain Tasman in the 1600s?  When found, their material culture was hardly more complex than is true of chimpanzees.  This, of course, says nothing about the complexity of the intangibles of their culture.  Were Tasmanians less than human because they had so little?  Certainly, many Europeans thought so since they willfully destroyed them.  But I think you will agree that racism is not a good way to judge whether a group is truly human or not.”

His response to this: “I think it’s OK to be racist against Neandertals. It’s the least of the offenses we are guilty of committing against them. In seriousness, though, they are extinct.”

My response to him: “So you think it is OK to have racist views about extinct populations?  Since the Tasmanians and Taino (among many other groups) are effectively extinct in the same sense that Neanderthals are extinct (i.e. their genes live on in current individuals, but their culture is gone), were (are) racist attitudes towards them OK?  Isn’t it racism that was key to their extinction?”  He did not respond to that e-mail.  Perhaps he realized he had gone too far.  Perhaps he was annoyed that I refused to accept his “obvious” evidence.