Maciamo
03-07-09, 00:10
Dienekes posted a new article about the genetic discontinuities between Etruscans and modern Tuscans (http://dienekes.blogspot.com/2009/07/genetic-discontinuities-between.html). He also notes the great variance in ancient and modern mtDNA haplogroups in Britain (http://dienekes.blogspot.com/2005/09/ancient-british-mtdna.html) and Central Europe (http://dienekes.blogspot.com/2005/11/mtdna-of-early-central-european.html), among others.
I was wondering what could be the reason for this radical change in haplogroup distribution over time. I have come up with the following hypothesis. As is often the case hypothesis are not necessarily exclusive but could very well be complementary.
1) some haplogroups confer a physical advantage, such as increased fitness or resistance to diseases, or increased fertility for women. If this is the case, then the same disadvantageous haplogroups should be declining in every region, regardless of the local geography, culture, wars or migrations.
2) some haplogroups are better adapted to some specific climates than others. There is already some evidence of this, for example with hg J, which is associated with a higher production of body heat (hence beneficial in colder climates like Norway).
3) The Indo-European migrations (and other migrations) have partly (and possibly massively) replaced indigenous haplogroups, both for Y-DNA and mtDNA. I see increasing evidence for this, especially since the evolution between ancient and medieval populations is much more dramatic than between medieval and modern.
Of particular interest is the sharp decline in haplogroup N1a in Central Europe since the Neolithic period.
In Scandinavia, it is especially haplogroups I and X that have experienced the biggest drop. In Britain, U5a1, T, W and X have all fallen considerably in frequency, while H and K have augmented.
Overall, it seems from the data I have observed that H and K are generally on the rise, and also happen to have the most favourable medical associations. The widespread distribution of N1a, I, W and X seem to indicate that they have been once been common all over Europe, but are now disappearing.
I have noted a similitude in the distribution between mtDNA hg X and Y-DNA hg G, as well as between mtdna I and Y-DNA hg I1. N1a might be related to Y-DNA I2a. If that is so, the Indo-Europeans could have been responsible for the demise of these haplogroups, to the profit K and some branches of H and U (U3, U4, but not U5a1). Combined with a physiological advantage, the new haplogroups would have continued to progressively replaced the older ones well after the presumed period of violent invasion. Of course this is nothing more than a wild personal guess at the moment.
I was wondering what could be the reason for this radical change in haplogroup distribution over time. I have come up with the following hypothesis. As is often the case hypothesis are not necessarily exclusive but could very well be complementary.
1) some haplogroups confer a physical advantage, such as increased fitness or resistance to diseases, or increased fertility for women. If this is the case, then the same disadvantageous haplogroups should be declining in every region, regardless of the local geography, culture, wars or migrations.
2) some haplogroups are better adapted to some specific climates than others. There is already some evidence of this, for example with hg J, which is associated with a higher production of body heat (hence beneficial in colder climates like Norway).
3) The Indo-European migrations (and other migrations) have partly (and possibly massively) replaced indigenous haplogroups, both for Y-DNA and mtDNA. I see increasing evidence for this, especially since the evolution between ancient and medieval populations is much more dramatic than between medieval and modern.
Of particular interest is the sharp decline in haplogroup N1a in Central Europe since the Neolithic period.
In Scandinavia, it is especially haplogroups I and X that have experienced the biggest drop. In Britain, U5a1, T, W and X have all fallen considerably in frequency, while H and K have augmented.
Overall, it seems from the data I have observed that H and K are generally on the rise, and also happen to have the most favourable medical associations. The widespread distribution of N1a, I, W and X seem to indicate that they have been once been common all over Europe, but are now disappearing.
I have noted a similitude in the distribution between mtDNA hg X and Y-DNA hg G, as well as between mtdna I and Y-DNA hg I1. N1a might be related to Y-DNA I2a. If that is so, the Indo-Europeans could have been responsible for the demise of these haplogroups, to the profit K and some branches of H and U (U3, U4, but not U5a1). Combined with a physiological advantage, the new haplogroups would have continued to progressively replaced the older ones well after the presumed period of violent invasion. Of course this is nothing more than a wild personal guess at the moment.