Sunday, April 27, 2008

The Origins of Indians: Version 8.1

Coastal Migration Theory and I:
As I have mentioned before I am skeptical about Coastal Migration Theory. This theory proposes a set of Homo Sapiens after leaving Africa rapidly colonized South Asia, SE Asia and Australia moving rapidly along the coastal regions. Y-Haplogroup C is generally considered as the marker of that coastal migration.

One of the C's in India belong to subclade C5 is distributed across India. However, there are C* in South India that might be the legacy of coastal migration. I compared the tribes and castes that carry this lineage and I observed a strange pattern in its association with other haplogroups.

I make the following assumption before coming to my conclusions.

If a haplogroup is observed in more than one endogamous tribe/caste then its uncharacteristic presence in any group cannot be explained with genetic drift or bottleneck or founder effect.

That haplogroup in the below table is R1a1. As far as I can see C* is observed in conjunction with R1a1.

Tribe/Caste: Observed Haplogroups - Region
Koya Dora/Konda Reddy - F, H, O2a - South - East
Kurumba - F, H, R2, L1 - South - West
Kamar - F, H, L1, O2a - South - East
Yerava - F, H, C*, R1a1 - South - West
Koraga - H, R2, YAP - South - West
Toda - L1, J2a, R1a1, C* - South - West
Pallar - F, H, R1a1, C*, J2b- South - West
L1, R2

Based on the above data I propose the following pre-neolithic migrations.
1. Africa-Middle East-South Asia : F, H
2. ? -> East India : O2a
3. Central Asia - south west coastal India : R1a1, C* (one of the first migrations of R1a1)
4. ? -> south-west India: L1
5. ? -> south-west India: R2

I don't see the possibility of coastal migration with this scenario.

Sources:
1. Cordaux et al. 2004
2. Sengupta et al. 2006

6 comments:

Maju said...

You have F* and C* all around! How come you don't see the possibility of the "coastal" migration model? Admitted that it could have gone as well through the interior of India but that doesn't make much of a difference anyhow.

In any case, early humans must have wandered in small groups that could have left no trace after all these milennia. Founding effects, drift, total displacement of groups from one place to another, possibly total extinction of some bands... all that mounts up against finding "the original thing" still around.

But you seem to have found enough traces of it against all odds, what I understand supports the "coastal" migration model.

Manjunat said...

Admitted that it could have gone as well through the interior of India but that doesn't make much of a difference anyhow.

That's why I have give south-east and south-west orientation of the tribes. It's impossible that C* has moved interior India as south-east tribes do not have it. If at all, it must have moved along the coast.

But you seem to have found enough traces of it against all odds, what I understand supports the "coastal" migration model.

No, check Toda haplogroups. C* appears without F or H. Further R1a1 is the common haplogroup with C* everywhere.

Maju said...

No, check Toda haplogroups. C* appears without F or H. Further R1a1 is the common haplogroup with C* everywhere.

But the other two samples where it's present, it does appear with F and H. Hmmm... I got for a moment attracted by your suggestion of C* and R1a1 migrating together but it doesn't seem so convincing on second sight, IMO. Not impossible anyhow.

How much C* is there in Central Asia (likely origin of Indian R1a1)? Is there a really consistent pattern of C*+R1a1 association all through the subcontinent? As always, context is all.

If the R1a1+C* association is exclusive of Southern India it may be a founder effect internal of the subcontinent (i.e. C* was there somewhere and got associated with R1a1 already in India, as it migrated southwards).

My two cents in any case.

Maju said...

Also...

It's impossible that C* has moved interior India as south-east tribes do not have it. If at all, it must have moved along the coast.

Why does it have to be tribal. On the Paleolithic everybody was tribal but most of their descedants in modern India surely are not anymore.

Also what about NE India (Bengal, Bihar)? the Narmada-Son-Ganges route links Mahrastra with Bengal.

Maju said...

Sorry to insist. The more I look at it the more I see all the elements in SE India: F*, C* and YAP (DE*). Btw, have you edited the post or was I careless skipping some of that info?

You say that:

If a haplogroup is observed in more than one endogamous tribe/caste then its uncharacteristic presence in any group cannot be explained with genetic drift or bottleneck or founder effect.

But C* is not a haplogroup properly speaking but a paragroup. A pragroup that apparently is only observed in South Asia and parts of SE Asia, a totally different distribution than that of R1a1. A distribution that fits well with the coastal migration model.

Manjunat said...

I'll elaborate on this soon.