Debates of the Sykes Y-STR results--论文代写范文精选

计算表明,对于一个简单的模型,它不会被不合理的假设所误导,只有家庭幸存下来,并达到相当数量。典型的发展是几个家庭共用相同的姓氏。此外,根据斯特奇模拟的数据,主要赛克斯的家庭数量存在异常。下面的essay代写范文进行详述。

The Sykes study led to some debate as to whether its Y-clustered result might imply that even the initial bearers of the surname could have had a single origin. Addressing this, Redmonds commented, ‘It is the number of potential origins [as judged by linguistic considerations] that explains the reluctance of some surname experts to think of Sykes as a possible single origin surname, and the [DNA] results were bound to lead to debate’.22 The DBS23 lists occurrences of some similar by-names, including de Sich (Norfolk, 1166); del Sikes (Yorkshire, 1309); in le Syche (Staffordshire, 1332); and, Reaney associates these with residence near streams or gullies. Rather than a single origin, many origins might be expected for the initial bearers of a topographical name such as this. Leaving aside by-names, a single origin is possible; but, it is not necessary to explain the Y-STR result of a single ancestor featured surname. Some further insight can be gained by considering some theoretical modelling. 

Monte Carlo computer simulations do not rule out plural origins for this surname which then led on to just one family dominating the Y-STR results. For a simple model, 24 the computations suggest that it would not be unreasonable to suppose that the Sykes surname had originated with eight different forefathers, instead of just one; and, that the families from only two of them had survived, with only one family having reached significant numbers.25 Still fewer families survive in a computer simulation that begins before the mid-fourteenth century Black Death.26 Families can be expected to have become extinct in the typical development of several families sharing the same surname. 

Moreover, on the basis of the Sturgess and Haggett simulations (Appendix B), the main Sykes family has proliferated abnormally to dominate the Y-STR results. This leaves further room for there perhaps having been initially many families called Sykes of which most have now died out or have been swamped in the Y-DNA results by the preponderant evidence for the unusually large main Sykes family. Rather than a ‘single origin’ for all of the initial bearers of this surname, a somewhat less bold hypothesis can be considered: to wit, that the surname may have had several origins but that the modern, prolific Sykes family has long been dominant. 

Such a proposition is not new. McKinley favoured that common surnames had an early populous showing;27 and, as Hanks puts it in the DAFN, ‘in standard statistical textbooks … (broadly) … frequent [sur]names [or families] tend to become more frequent, while infrequent [sur]names [or families] tend to become less frequent’.28 One might hence consider a scenario in which the main Sykes family could have been frequent amongst the early, recorded instances of this name. Even so, some of the early records could have been for other less-populous Sykes families before they became extinct or drifted to relative rarity. Accordingly, there remains room for scepticism about a proposition that separate, early documentary records for the name can be considered to belong to a single family. 

Nonetheless, taking all the evidence together and referring to comments by Redmonds,29 Hanks30 offered the hedge ‘probably’ when supposing that the main Sykes family could have developed early in Flockton, before being found about twelve miles away in Slaithwaite.31 The Sykes Y-STR results shifted the balance of opinion for a populous surname. Redmonds32 commented, ‘When I suggested in 1973 that Brook was principally a Huddersfield surname, with a very restricted number of family origins, it was not a popular view, but recent research into the Sykes Y chromosome has made the idea far more acceptable’. The seminal Sykes result had made it more acceptable to consider that a single family could grow to the extent of a populous surname. However, though there is yet no result for Brook, more recent Y-STR evidence is now suggesting that a single ancestor featured result might not arise for many common surnames in England.

Some more recent Y-STR results for Ireland 
A particularly common Y-STR signature, found in north-west Ireland,33 has been attributed to the hegemony of the mythical Uí Néill (308-405AD). A likely time scale has been estimated from early, northern Irish, genealogical records and also the genetic diversity of the matching males;34 and, this suggests proliferating origins around the times of Uí Néill and gives rise to an overall, estimated growth rate for his family of 21% per generation.35 This single-family feature has not been found for other Irish tribes.36 McEvoy and Bradley37 considered several Irish surnames and they found that Ryan and O’Sullivan, for example, displayed a high fraction of Y-STR matches at about half, in the manner of the Sykes result, whereas Kelly and Murphy for example displayed few matches. 

They suggested, for O’Sullivan, a historical rate of false paternity events (i.e. male introgressions) of 1.6% per generation by assuming n=35 generations of 30 years since c950AD (Appendix A). Ryan and O’Sullivan each have as many as 38,000 bearers in Ireland; and, it can be concluded, for these populous surnames, that at least a significant fraction of their living bearers belong to their respective main families. This finding of a large, main family holds irrespective of a debate as to whether the Y-mismatches should be attributed solely to male introgressions into a single origin surname, or partly instead to extant descent from plural origins. The main Ryan and O’Sullivan families, as well as some others, have proliferated more than the Sturges and Haggett computer simulations predicted (Appendix B). 

These simulations are for monogamous families with mid-fourteenth century origins and they foretell a maximum size of no more than several hundred for a single family. However, Sturges and Haggett added that a surname could have had several members already by the mid-fourteenth century; and, there is a general point: early conditions are important to the eventual, expected family size. Though a fortuitous combination of other factors could lead to high growth (Appendix B), a particular explanation for a single family’s large size is that it set off to a fast start. This could happen most dramatically if it began with many bastards.38 This would avoid the limitation that the wife of a monogamous man can bear only a restricted number of children. Also, beginning with sufficiently many bastards would avoid the erratic vicissitudes of initial family growth39 and apply a large multiplier to the whole of the subsequent population of the family.40 However, it needs to be assumed that the bastards shared the same surname, for such an explanation to hold for a large, single surname family.

A populous, single ancestor featured surname: Plant 
The case study of the Plant surname serves to illustrate some debate about polygyny and the development of a large, single ancestor featured surname. It seems that a sizeable fraction, at least, of the Plant surname derives from a single family (Appendix C) and that this family has grown abnormally (Appendix B). If the population of this populous, English surname had grown at the rate of the general population, that is 14% per generation, there would have needed to have been 591 Plants by 1360 to account for the 12,034 Plants in England and Wales by now.41 However, some surnames grow faster than others: Plant grew in the UK at about 26% per generation between 1881 and 1981.42 Though precise past rates of growth for particular families remain uncertain, extrapolating back the high 26% rate reduces the estimated Plant family size in 1360 to 59.43 Variations to this estimate are possible. 

For example, the number would be rather fewer if not all of the modern Plant population were taken to represent the size of the main single family.44 On the other hand, it would be several times higher if one were to take account of early growth normally being slower in early, less favourable times than that between 1881 and 1981.45 On balance, despite the uncertainties, this estimation of perhaps around 60 Plants in the mid-fourteenth century is adequate to illustrate that the Plants could have been numerous since early times. Further debate is controversial. One possible explanation of the populous Plants is that they were polygynous offspring; but, it can be questioned whether all such children would inherit the same surname. Though Welsh Law was favourable towards those whom the English would call ‘illegitimate’, a bastard had no right to inherit a surname in English Law.46 

Though there is an intimation of bastardy in the Plant blazon47 and though the main homeland of the Plants was in the Marches bordering Wales, it is open to debate whether a Welsh influence could have allowed inheritance of the name through polygyny. It is no better than contentious for one to venture to suggest, for the main Plant homeland, that the name might have been coined for the ‘many children’ of a single family, albeit that the Welsh meaning ‘children’ of plant seems less likely to have been prevalent in SE England and France, where there are other early instances of the name. Certainly, it should be stressed that there are other possible meanings for this name (Appendix C).

Some recent Y-STR results for English surnames 
A recent scientific study highlights a complication that is more likely to arise for nonpopulous surnames. The progress of such a surname might have been erratic for a long time before attaining more steady growth only recently. Such recent proliferation might give rise to many nominal close relatives amongst the Y-DNA tested men sharing a surname. A most recent common ancestor (MRCA) can be considered, before whom the paternal lines of a set of Y-matching men coincide. Genealogical information can often indicate a minimum time depth during which the paternal lines for single ancestor men did not coincide (Appendix C). In the absence of documentary evidence however, a different approach is needed.（essay代写)

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