The discovery of the similarity of Sanskrit with European languages by Sir William Jones led to the theory of that there was originally a Proto-Indo-European language (PIE) from which all the related languages evolved. The Proto-Indo-European linguistic problem then became the Proto-Indo-European biological problem and it morphed into the Aryan Invasion Theory with Aryans invading and displacing Dravidian speakers from the Punjab region. For linguists, one important question is in finding the time frame of this hypothetical language. There must have been a time when PIE originated, stayed alive and then ceased to exist. It is believed by some linguists PIE originated between 4000 – 3500 BCE and died by the start of the Mature Harappan Period (2600 BCE).
Now a new paper suggests that there was an older common ancestor which existed around 15,000 years back. Some of the words used from the ice age have been retained in related forms since that period. The paper uses a genetic study which claims that Dravidians expanded from Central Asia to South Asia much before the migration of the Indo-Europeans and uses that to set a much older date for Proto-Dravidian. The map below show the migration of Dravidians and the arrow seems to point to

This seems like a Dravidian nationalist dream come true. But all is not well with this theory. If you notice the map, you will find that the Dravidian speakers ending up in the Brahui region of Balochistan. While it was believed that they were the remnants of the Dravidian speakers who did not migrate to the South following the arrival of the Indo-European speakers, it is now believed that they migrated from Central India in 1000 CE.
There are other serious issues as well.

There are many variables in the reconstructions, and many the forms themselves often bear little resemblance to mainstream Indo-Europeanists’ reconstructions. The semantic looseness is often extreme. For instance, the database glosses a reconstructed form *(a)den@gh- (where @ = schwa) as `to reach, to seize, to have time’. Among the proposed descendants of this form are a Tocharian B form meaning `rise, raise oneself up’, an “Old Indian” (Sanskrit?!) form meaning `reach, strike’, an “Old Greek” (Ancient Greek?!) form meaning `with the teeth, biting together’, and an Old Irish form meaning `repress, oppress, suppress, crush, put down’. This is typical of the semantic latitude. Formally, too, there are problems. The proposed “Old Indian” descendant of this proto-word is given as daghnoti, possibly on the assumption that the nasal of the reconstructed root metathesized with the gh; but the nasal of the Sanskrit form is a present tense suffix, not part of the root at all. So Sanskrit (by whatever name) doesn’t match the database’s proto-word phonetically.
If the reconstructions used by Pagel et al. for their statistical analyses are not reliable in either form or meaning, then the statistical results of comparing these reconstructions cannot provide any evidence for distant relationships among the seven groups they compare. If the selection procedure for choosing among several candidate proto-words to use for the statistical analysis is flawed, then there may be problems with the statistics as well. But even if there are no statistical flaws, the Pagel et al. paper is yet another sad example of major scientific publications accepting and publishing articles on historical linguistics without bothering to ask any competent historical linguists to review the papers in advance.[Ultraconserved words? Really??]

Here is another criticism of the paper

Pagel and Atkinson’s search for family relationships among languages is set off course at the onset by looking in the wrong place. It has been understood at least since Antoine Meillet’s work a hundred years ago that grammatical properties are more reliable than words as indicators of familial relationships. As Meillet (1908: 126) noted “Les coincidences de vocabulaire n’ont en general qu’une très petite valeur probante” (“Coincidences of vocabulary are in general of very little probative value”). In recent years, the searchlight has been focused—by bone fide linguists, not evolutionary biologists—on abstract syntactic properties, establishing formal grammar as a population science; see, for example, the work of Giuseppe Longobardi and Cristina Guardiano (e.g. Longobardi & Guardiano 2009). Just as the biological classification of species, originally based on externally accessible characteristics, underwent a revolution on the grounds of progress in theoretical biology, namely the rise of molecular genetics, so too progress in the phylogenetic classification of languages must be based on progress in theoretical linguistics. In order to push the research frontier, we linguists need to identify the basic building blocks of language, its “atoms”, in Mark Baker’s memorable metaphor, and examine carefully how they play out in linguistic evolution. Looking for “words that survived since the last Ice Age”, in contrast, is a seductive but ultimately a futile enterprise. [Do “Ultraconserved Words” Reveal Linguistic Macro-Families?]

And finally

In short, “Ultraconserved words point to deep language ancestry across Eurasia” is premised on the notion that cutting-edge research in historical linguistics requires little knowledge of linguistic geography, linguistic history, or even linguistics itself. It is hardly surprising that such a research program would yield inadequate results. [Do “Ultraconserved Words” Reveal Linguistic Macro-Families?]

References:

1. Anthony, David W. The Horse, the Wheel, and Language: How Bronze-Age Riders from the Eurasian Steppes Shaped the Modern World. Reprint. Princeton University Press, 2010.
2. Bryant, Edwin. The Quest for the Origins of Vedic Culture: The Indo-Aryan Migration Debate. Oxford University Press, USA, 2004.
3. Pagel, Mark, Quentin D. Atkinson, Andreea S. Calude, and Andrew Meade. “Ultraconserved Words Point to Deep Language Ancestry Across Eurasia.” Proceedings of the National Academy of Sciences (May 6, 2013). doi:10.1073/pnas.1218726110.