PDA

View Full Version : New research paper finds 6000-year-old admixture in Ecuadorians, but then denies it?



lgmayka
11-21-2014, 10:43 AM
Take a look at this research paper abstract (http://www.fsigenetics.com/article/S1872-4973(14)00245-2/abstract). It says:
---
Second, we analysed 207,321 single nucleotide polymorphisms from 16 Ecuadorian individuals, comparing them with populations from the HGDP panel using descriptive and formal tests for admixture. Our simulations revealed good power to detect recent admixture, and that ≥5% admixture 6 Kya ago could be detected. However, in the experimental data we saw no evidence of gene flow from Japan to Ecuador. In summary, we can exclude recent migration and probably admixture 6 Kya as the source of the C3* Y chromosomes in Ecuador, and thus suggest that they represent a rare founding lineage lost by drift elsewhere.
---

This appears to be self-contradictory:

- They found over 5% admixture from 6000 years ago in modern Ecuadorians

- The admixture was not from Japan

- So they have decided to deny that they ever found the admixture at all.

Can someone with access to the full paper determine: Does their data show admixture or not? And if so, from where? Ignore any false denials in their conclusion.

The alleged Ecuador-Japan connection apparently refers to a controversial hypothesis relating the Valdivia and Jomon cultures (http://en.wikipedia.org/wiki/Valdivia_culture).

ArmandoR1b
11-21-2014, 02:06 PM
Take a look at this research paper abstract (http://www.fsigenetics.com/article/S1872-4973(14)00245-2/abstract). It says:
---
Second, we analysed 207,321 single nucleotide polymorphisms from 16 Ecuadorian individuals, comparing them with populations from the HGDP panel using descriptive and formal tests for admixture. Our simulations revealed good power to detect recent admixture, and that ≥5% admixture 6 Kya ago could be detected. However, in the experimental data we saw no evidence of gene flow from Japan to Ecuador. In summary, we can exclude recent migration and probably admixture 6 Kya as the source of the C3* Y chromosomes in Ecuador, and thus suggest that they represent a rare founding lineage lost by drift elsewhere.
---

This appears to be self-contradictory:

- They found over 5% admixture from 6000 years ago in modern Ecuadorians

- The admixture was not from Japan

- So they have decided to deny that they ever found the admixture at all.

Can someone with access to the full paper determine: Does their data show admixture or not? And if so, from where? Ignore any false denials in their conclusion.

The alleged Ecuador-Japan connection apparently refers to a controversial hypothesis relating the Valdivia and Jomon cultures (http://en.wikipedia.org/wiki/Valdivia_culture).

Maybe they could have chosen better wording but what they are saying is that their simulations were shown to have the power to detect ≥5% admixture 6 Kya ago when it exists in other populations. Based on their conclusion they are saying that they did not detect ≥5% admixture 6 Kya ago in the Ecuadorians and therefore it does not exist in the Ecuadorians.

lgmayka
11-21-2014, 03:03 PM
Maybe they could have chosen better wording but what they are saying is that their simulations were shown to have the power to detect ≥5% admixture 6 Kya ago when it exists in other populations. Based on their conclusion they are saying that they did not detect ≥5% admixture 6 Kya ago in the Ecuadorians and therefore it does not exist in the Ecuadorians.
Hmm, your interpretation is probably correct. However, their conclusion then ought to more cautiously state that any such Ecuadorian admixture (if it exists) is below the 5% level.

ArmandoR1b
11-21-2014, 03:23 PM
Hmm, your interpretation is probably correct. However, their conclusion then ought to more cautiously state that any such Ecuadorian admixture (if it exists) is below the 5% level.

They do cautiously state "we can exclude recent migration and probably admixture 6 Kya as the source of the C3* Y chromosomes in Ecuador" They do not state that it is definitive proof. I am sure that once the phylogenetic is better defined that the Japanese and Ecuadorians will not have SNPs in common in at least the last 10,000 years.

Anglecynn
11-21-2014, 06:28 PM
Presumably they say could implying that the technology would be able to detect admixture greater than 5% within a 6000 year timescale, but despite this ability they found no evidence - hence their conclusion. I agree it is worded a bit oddly.