Another look at South Asian aDNA

With Narasimhan et al (2018), we got our first look at Central, South Central, and South Asian aDNA. Not only did we get to see new steppe samples throughout the Bronze Age, but even from the Chalcolithic, through the Bronze Age in the Turan region, including BMAC. While there certainly looks to be steppe ancestry in South Asia, it has likely been highly inflated with previously available aDNA, and those that did not account for ANE that was already present in the region. The anticipation of the soon to be released Harappan sample(s), the models will only improve further.

This post will be constantly evolving as I add new outputs from qpAdm and qpGraph, so keep checking back in.

What I have noticed using qpAdm is that South Asian Dravidians do wonders as stand-ins for Harappan ancestry. So, we may see that some group greatly resembles them. I have seen that using the Palliyar and Paniya does work well, but the Irula does seem to work best. I don’t know whether that really means anything or the fact that they have more coverage.

The first thing I did was to look for populations to occupy the right pops, or populations which create the most significant D-stats between my left populations, or those set as the populations used in the mixture. Aside from using an African, Mbuti_DG, I found that using Ust-Ishim, Onge, Ami, EHG, Iron_Gates, Anatolia_N, Ganj_Dareh_N, and Karitiana. Kostenki14 is a hit and miss, as it doesn’t always have significant stats involved comparing two populations. This could be due to the age of the sample and not really developing any significant drift that can help differentiate populations in the test. This can lead higher chi-squares and lower tail-probabilities.

For the following, Brahmin_SGDP and Brahmin_Tiwari did have good marker counts, ranging from 170-200K, but the Brahmin_TN and Brahmin_UP sit around 50K, so they should be taken with a grain of salt.

SIS1= Shahr_I_Sokhta_BA1

Arm_EBA= Armenia_EBA

 

SGDP chisq tail prob SIS1 Irula Sintashta Dali_EBA Arm_EBA
w Kostenki 2.872 0.82475 0.208 0.623 0.1 0.069 NA
std error 0.038 0.035 0.036 0.035 NA
w/o Kostenki 2.031 0.844866 0.212 0.62 0.103 0.065 NA
std error 0.037 0.034 0.036 0.035 NA
w Kostenki 1.868 0.760109 0.167 0.609 0.065 0.097 0.063
std error 0.071 0.034 0.063 0.051 0.08
w/o Kostenki 2.599 0.761475 0.178 0.61 0.057 0.097 0.058
std error 0.063 0.035 0.065 0.046 0.081
Tiwari chisq tail prob SIS1 Irula Sintashta Dali_EBA Arm_EBA
w Kostenki 8.292 0.217452 0.138 0.583 0.208 0.071 NA
std error 0.025 0.021 0.023 0.02 NA
w/o Kostenki 7.332 0.19711 0.139 0.577 0.211 0.073 NA
std error 0.025 0.02 0.023 0.02 NA
w Kostenki 5.855 0.320606 0.089 0.579 0.154 0.099 0.08
std error 0.04 0.021 0.039 0.026 0.049
w/o Kostenki 5.351 0.253112 0.096 0.574 0.162 0.097 0.071
std error 0.039 0.02 0.039 0.026 0.049
TN chisq tail prob SIS1 Irula Sintashta Dali_EBA Arm_EBA
w Kostenki 0.925 0.988309 0.156 0.656 0.113 0.074 NA
std error 0.043 0.039 0.04 0.04 NA
w/o Kostenki 0.557 0.989882 0.168 0.643 0.117 0.072 NA
std error 0.042 0.037 0.038 0.039 NA
w Kostenki 0.861 0.973004 0.145 0.653 0.097 0.086 0.019
std error 0.079 0.039 0.073 0.049 0.095
w/o Kostenki 0.0624 0.960366 0.191 0.638 0.13 0.068 -0.027
std error 0.079 0.038 0.072 0.049 0.093
UP chisq tail prob SIS1 Irula Sintashta Dali_EBA Arm_EBA
w Kostenki 7.561 0.272087 0.147 0.598 0.181 0.075 NA
std error 0.032 0.028 0.031 0.031 NA
w/o Kostenki 5.636 0.343262 0.151 0.59 0.188 0.071 NA
std error 0.031 0.027 0.029 0.029 NA
w Kostenki 7.338 0.196693 0.11 0.599 0.144 0.094 0.054
std error 0.066 0.028 0.059 0.039 0.081
w/o Kostenki 5.866 0.209375 0.136 0.59 0.171 0.08 0.022
std error 0.061 0.027 0.054 0.037 0.073

NEW-8-9-18

Dzh1 = Dzharkutan1_BA, Late BMAC

Steppe_E = Steppe_MLBA_East

SGDP chisq tail prob Irula Dzh1 Sintashta Steppe_E Dali_EBA
w Kostenki 6.954 0.433685 0.681 0.203 0.116 NA NA
std error 0.023 0.034 0.028 NA NA
6.294 0.505837 0.678 0.198 NA 0.124 NA
std error 0.023 0.034 NA 0.028 NA
3.787 0.705485 0.629 0.225 NA 0.075 0.07
std error 0.029 0.036 NA 0.037 0.033

The above is interesting in that there are whole graves spread around from India to West Asia that are completely late BMAC in character. There seems no possible way for there to not be detectable BMAC ancestry in South Asia, considering the amount of cemeteries and remains. I think the Harappan sample(s) will show that BMAC ancestry is indeed important in South Asia.

Looking at the Swat Valley samples, it gets even more interesting…

Aligrama chisq tail prob Irula Dzh1 Steppe_E Dali_EBA
12.238 0.0568697 0.49 0.355 0.091 0.063
std error 0.03 0.036 0.034 0.03
Butkara_IA chisq tail prob Irula Dzh1 Steppe_E Dali_EBA
5.148 0.524941 0.404 0.489 0.03 0.077
std error 0.029 0.034 0.034 0.031
Pak_IA_Ali chisq tail prob Irula Dzh1 Steppe_E Dali_EBA
8.014 0.237064 0.431 0.419 0.087 0.063
std error 0.042 0.053 0.05 0.043
S_Sharif_IA chisq tail prob Irula Dzh1 Steppe_E Dali_EBA
8.433 0.208056 0.437 0.364 0.141 0.059
std error 0.018 0.023 0.022 0.018
SPGT chisq tail prob Irula Dzh1 Steppe_E Dali_EBA
11.378 0.0773638 0.316 0.503 0.113 0.069
std error 0.014 0.018 0.018 0.015

Interestingly, there seems to be no need for Andronovo admixture in Butkara, Pakistan_IA_Aligrama, and also the first Aligrama can do okay with just Dali, plus late BMAC. Of course, this all depends on the underlying population being similar to the Irula. Either way though, the Steppe ancestry should really not move. Next, I’ll see how including all BMAC samples affects the output.

Aligrama chisq tail prob Irula BMAC Steppe_East WSiberia_N
15.054 0.0198432 0.5 0.359 0.083 0.058
std error 0.027 0.036 0.034 0.022
Butkara_IA chisq tail prob Irula BMAC Steppe_East WSiberia_N
8.929 0.177591 0.411 0.477 0.052 0.06
std error 0.025 0.033 0.034 0.022
Pak_IA_Ali chisq tail prob Irula BMAC Steppe_East WSiberia_N
6.755 0.344126 0.438 0.402 0.104 0.055
std error 0.037 0.053 0.05 0.032
S_Sharif_IA chisq tail prob Irula BMAC Steppe_East WSiberia_N
10.458 0.106644 0.442 0.368 0.144 0.046
std error 0.015 0.022 0.022 0.013
SPGT chisq tail prob Irula BMAC Steppe_East WSiberia_N
8.626 0.195754 0.313 0.509 0.102 0.076
std error 0.011 0.016 0.015 0.009

 

 

 

 

 

 

8 thoughts on “Another look at South Asian aDNA”

  1. Thanks, I was looking forward to this.
    Have you been able to estimate any steppe admixture in Irula itself? I think it could be around 5%, some the admixture from Irula in the models above hovering around 60% would mean that the steppe admixture might increase some 3%.
    Using Eurogenes’ Global 25 I get around 20% Sintashta in Brahmin_UP and 15% in Bramin_TN, so if that 5% in Irula is real then the results would be very close.

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  2. I think the Irula can have 0% actual steppe. They also lack any R1a, from what I can see, which is not very common. I think that we will see BMAC ancestry starts to peek its head out. We will see those graves weren’t a dead end in South Asia. Turan-like admixture may be higher than steppe ancestry in South Asia.

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  3. Nice work Chad
    It seems that IA Swat samples are predominantly of Irula -type & BMAC ancestry, with anything between 3-14 % of steppe MBA and also some Siberian-type admixture.
    Based on the received narrative, are we to expect that most of the Indus region was still non-IE in the late Iron Age? Perhaps there is an archaeologically invisible steppe – “Hub” in the plains of Punjab

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  4. It’s hard to say and I don’t like getting into linguistics too much, but there are a couple groups from IA Swat that need no Steppe MLBA for a plausible fit. Even Brahmins are comparable to these groups, so I still think Steppe ancestry has been very inflated in South Asia. BMAC is the more visible group archaeologically and would also be genetically speaking here.

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  5. @Al Bundy, sorry about that. If you still can’t access it, could you contact me (alberto6674 at gmail dot com) so I can figure out the problem? Thanks for reporting it.

    @Chad, sorry, as soon as Al sees my message feel free to delete these off topic messages.

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