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Mahammad Pur Umri is small enclaved village located near Allahabad. It possesses an unusually high rate of identical twinning. We first traveled there in December 2008 to investigate the origin of this singular phenomenon. We returned with National Geographics in 2011.
Mahammad Pur Umri is small enclaved village located near Allahabad. It possesses an unusually high rate of identical twinning. We first traveled there in December 2008 to investigate the origin of this singular phenomenon. We returned with National Geographics in 2011.
Three hypotheses can be formulated:
Three hypotheses can be formulated:
1) The twinning rate is not as elevated as believed
1) The twinning rate is not as elevated as believed
Taking into account, the current population of the village (estimated between 2000 and 2500 people), its annual birth rate (estimated between 10 and 15 newborn a year) and the net flux of people settling in or leaving the village, we estimate the monozygotic twinning rate to be at least 3 times higher than of the dizygotic twinning rate. This alone argues that Mohammad Pur Umri indeed affords an unusual number of multiple births. Its DZ to MZ birth ratio is inverted compared to that of the general population, leading to a conservative approximation of 1 in 50 births witnessing a pair of monoclonal humans being born.
Taking into account, the current population of the village (estimated between 2000 and 2500 people), its annual birth rate (estimated between 10 and 15 newborn a year) and the net flux of people settling in or leaving the village, we estimate the monozygotic twinning rate to be at least 3 times higher than of the dizygotic twinning rate. This alone argues that Mohammad Pur Umri indeed affords an unusual number of multiple births. Its DZ to MZ birth ratio is inverted compared to that of the general population, leading to a conservative approximation of 1 in 50 births witnessing a pair of monoclonal humans being born.
2) An environmental factor is responsible for increased MZ twinning
2) An environmental factor is responsible for increased MZ twinning
While this possibility should not be ignored, no reported chemical or particular lifestyle is known to increase the chances of MZ twinning. Villagers have told us that multiple births in water buffaloes have been observed in the village in the past 30 years. 2-yolk eggs have been seen as well. Coincidentally the increase in MZ twinning can be associated with the establishment of an Air-force base some 40 years ago, or it is simply correlated with better medical care and know-how in the last two generations.
While this possibility should not be ignored, no reported chemical or particular lifestyle is known to increase the chances of MZ twinning. Villagers have told us that multiple births in water buffaloes have been observed in the village in the past 30 years. 2-yolk eggs have been seen as well. Coincidentally the increase in MZ twinning can be associated with the establishment of an Air-force base some 40 years ago, or it is simply correlated with better medical care and know-how in the last two generations.
3) An dominant founder effect explains this seemingly inherited familial twinning
3) An dominant founder effect explains this seemingly inherited familial twinning
Marriages between relatives within a relatively ethnically-homogeneous population promotes the idea that a rare haplotype exists whose action leads to the early splitting of the human embryo during development. No such allele is known to exist although another mammal, the nine-banded armadillo, is tangible evidence that monozygotic splitting can have a genetic origin.
Marriages between relatives within a relatively ethnically-homogeneous population promotes the idea that a rare haplotype exists whose action leads to the early splitting of the human embryo during development. No such allele is known to exist although another mammal, the nine-banded armadillo, is tangible evidence that monozygotic splitting can have a genetic origin.
References about Mohammad Pur Umri:
References about Mohammad Pur Umri:
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