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Gene surfing is a process in population expansion whereby certain variations become prominent and dominant in a short time, appearing to skip the slow, steady, uniform accumulation of variegation and diversification. According to a study of the population structure and genealogies of Saguenay Lac-Saint-Jean in Quebec, this type of drastic change accompanied the immigrant wave front that spread over the area in the 17th century. "Deep Human Genealogies Reveal a Selective Advantage to Be on an Expanding Wave Front" in Science magazine describes the resulting demographics.

Abstract
Since their origin, human populations have colonized the whole planet, but the demographic processes governing range expansions are mostly unknown. We analyzed the genealogy of more than one million individuals resulting from a range expansion in Quebec between 1686 and 1960 and reconstructed the spatial dynamics of the expansion. We find that a majority of the present Saguenay Lac-Saint-Jean population can be traced back to ancestors having lived directly on or close to the wave front. Ancestors located on the front contributed significantly more to the current gene pool than those from the range core, likely due to a 20% larger effective fertility of women on the wave front. This fitness component is heritable on the wave front and not in the core, implying that this life-history trait evolves during range expansions.

So gene surfing in an expanding colonization phase can produce a genetic revolution whose effects will be felt for hundreds or thousands of years downstream in history.

We wonder if the same wave front demographics might explain some of the following population phenomena:

• Large scale triumph of Norman male lineages following the conquest of England in 1066.
• Selective expansion of Middle Eastern genes in Tennessee (including Cherokee families, Jewish male and female lines and Melungeons)
• Relatedness among Jews and "Jewish diseases"
• Diversity-within-uniformity of Polynesians
• Population replacement of Old European (U, N) by Middle Eastern genes (T, J)  in Europe as a result of the Neolithic Agricultural Revolution

Many students of history are puzzled why old populations have the allele frequencies and heterozygosity clines they have. Genetic drift is only part of the answer. Gene surfing and selection in deep history are the rest of it.

More information about Melungeons
Toward a Genetic Profile of Melungeons in Southern Appalachia
Melungeon Studies
Melungeon Match

A Missing Link from Kent's Cavern in Devonshire

A prehistoric maxilla (upper jawbone) fragment was discovered in the cavern during a 1927 excavation by the Torquay Natural History Society, and named Kents Cavern 4. The specimen is on display at the Torquay Museum.

Although previous radiocarbon dating suggested the bone was about 35,000 years old, a new study in Nature redates it securely to 44.2-41.5 kyr. The article by Tom Higham et al., "The Earliest Evidence for Anatomically Modern Humans in Northwestern Europe," also claims that on the basis of dental comparisons it is "human" rather than "Neanderthal."

The Kent's Cavern fragment "therefore represents the oldest known anatomically modern human fossil in northwestern Europe, fills a key gap between the earliest dated Aurignacian remains and the earliest human skeletal remains, and demonstrates the wide and rapid dispersal of early modern humans across Europe more than 40 kyr ago."

A related article in the same issue of Nature is "Early Dispersal of Modern Humans in Europe and Implications for Neanderthal Behavior," by Stefano Benazzi et al. It attempts to place the so-called Cavallo fossil from southern Italy in a timeframe of about 44,000 years ago, thus suggesting a "rapid dispersal of modern humans across the continent before the Aurignacian and the disappearance of Neanderthals."

Neither study considers that the evidence they are examining may be the result of hybridization between "humans" and "Neanderthals." Like most geneticists the authors have rigid categories and do not consider that our definitions of species and sub-species and transitions in technocomplexes and traits are in flux as new discoveries are made.

One man's Mede may be another man's Persian, and we note that the "fossil race" is not devoid of scientific jingoism pitting one country's news-making finds against another's. So far England seems to be winning.

However, the British still have to live down Piltdown Man, a fraud of biblical proportions that fooled the world for almost half a century until the 1950s. The Piltdown hoax is perhaps the most famous paleontological hoax ever. It has been prominent for two reasons: the attention paid to the issue of human evolution, and the length of time that elapsed from its discovery to its full exposure as a forgery combining the lower jawbone of an orangutan with the skull of a fully developed modern human.

The editors sum up the two new studies by writing, "The reanalysis of findings from two archaeological sites calls for a reassessment of when modern humans settled in Europe, and of Neanderthal cultural achievements." We wish that the paleontological community would think more out of the box and reassess how, when and where "humans" and "Neanderthals" interbred. 


Location of Kent's Caverns in Devon.

At a time when it seemed that American science had bitten off more than it could chew with the Human Genome Project, Craig Venter and his innovative company published "A New Strategy for Genome Sequencing." Appearing in the journal Nature in 1996, the Venter multi-center approach bypassed laborious gene mapping and allowed the HGP to meet its goal of full sequence information on the human genome in 2000.

"In the race to sequence the human genome," write the editors of Nature's DNA Technologies Milestones, "research groups had to choose between the random whole genome shotgun sequencing approach or the more ordered map-based sequencing approach." The choice of randomness versus order was present from 1982, but the Venter strategy was resisted for many years. Finally, in 1996 it was accepted and given an equal emphasis with the more orthodox approach.

After a standoff between the two groups of scientists, "a showdown ensued, with the biotechnology firm Celera Genomics wielding whole-genome shotgun sequencing and the International Human Genome Sequencing Consortium wielding map-based sequencing. Yet when the dust settled, it was a draw -- both groups published their initial drafts of the human genome concurrently in 2001."

The maverick technology helped make high throughput genomic sequencing at commercial labs an economy reality and gave birth to a range of new DNA tests within the reach of ordinary consumers like you and me. Today, fifteen years later, those interested in autosomal ancestry testing and personal genomics have biologist and entrepreneur Craig Venter and his irascible persistence as a scientific pioneer to thank.

A mental foramen is a small hole in the mandible whose purpose is to allow passage of nerves and vessels to the brain and probably also to relieve tension during chewing and gnawing. It has been identified as a sign of archaic humans, including Neanderthals. Do you have one?

I asked my dentist to look at my X rays on file and he confirmed I have a mental foramen. He has often told me I have "powerful" jaws. It is unclear whether there are normally two of them and what their typical positions are.

In a previous blog post, "Neanderthals in America," we discussed mental foramina (the plural of foramen), occipital bulges or bumps and other archaic skeletal traits. Melungeons seem to have many of these ancestral marks.

Do you? You might want to check with your dentist.

Studies show that Europeans have, on average, between 1 and 4 percent Neanderthal genes from an early out-of-Africa interbreeding period in the Middle East. Science has not decided to consider Neanderthals a separate species or sub-species in relation to H. sapiens sapiens (humans).

DNA Consultants offers an estimate of Neanderthal ancestry based on matches with other archaic humans called Neanderthal Index.

Line drawing of Neanderthal male ©DNA Consultants.



More information about Melungeons
Toward a Genetic Profile of Melungeons in Southern Appalachia
Melungeon Studies
Melungeon Match