Saturday, July 30, 2016

New Ancestor Of Man And Other Rants About Media Reports

I am ashamed to admit this, but these days I just shrug away the various instances of poor science reporting I notice in the Indian media. But enough outrage has been building up over a couple of  particularly bad misrepresentations of scientific findings to prompt this rant.

 1) Indian Scientists Find New Ancestor Of Man

One shudders with embarrassment at this jingoistic hyperbole. The study is an international collaboration. Why the chest beating?

The article in Deccan Herald on July 26 by Kalyan Ray completely misrepresents the evolutionary story of Homo sapiens. Here are the sentences which go badly wrong -

"Andaman’s Jarawas and Onges are descendants of a completely new family of early men unknown to science so far"..

"The discovery has the potential to open up a new window in the history of human evolution by suggesting that Homo heidelbergensis—the first group of men who came out of Africa—had given rise to multiple lineages and not just the Neanderthal and the Denisovan—the two known branches from which all modern human beings have evolved".

The writer is suggesting the modern humans evolved entirely from Neanderthals and Denisovans outside Africa and that this new research is showing that the Andamanese are descendants of a yet third branch of humans based outside Africa.

This picture given by Kalyan Ray is false. Take a look at the hominin family tree presented in the research paper.

Source: Genomic analysis of Andamanese provides insights into ancient human migration into Asia and adaptation

It presents our current understanding of human evolution and migration and admixing events between different branches of hominins. Modern humans migrating out of Africa about 60 thousand years ago met and admixed with the Neanderthals and Denisovans who were branches of an earlier wave of human migration out of Africa. This earlier wave of migration may have taken place about half a million years ago. This admixture between archaic and modern humans resulted in all living non -Africans having  2%-4% Neanderthal ancestry with additional Denisovan ancestry more common in Melanesians.  Now, this study is proposing that another unknown extinct hominid, a possible third diverged population from those earlier migrations, contributed a small amount of ancestry to south Asians. The Andamanese may be taken as an approximate proxy of the original modern humans who entered the Indian subcontinent from Africa since after diverging from a common South Asian population they have admixed less with other modern humans.

Another quibble is the sentence "Hominids are ancestors of the great apes and humans". Well, hominids is a grouping that includes both extinct and living great apes and humans. So yes, some extinct hominid would have been our ancestor, but modern humans are hominids too. As an aside, to confuse matters further, Hominin are the group that includes the extinct and living members of only the human family, excluding the chimpanzee, gorilla and orang-utans.

2) Before The Pharoah: Fresh Evidence Should Make Us Question Earlier Views Of Indus Valley Civilization

This piece which appeared in the Times of India on June 6 is referring to a paper about the link between Holocene monsoon record and the evolution of Harappan civilization. The authors also suggest a revision of the chronology of the various Harappan cultural stages.  Here is their proposed chronology.This is based mainly on the chronology proposed earlier by G.L Possehl. The authors of this study augment  that with new dates from two samples.

"The successive cultural levels at Bhirrana, as deciphered from archeological artefacts along with these 14C ages, are Pre-Harappan Hakra phase (~9.5–8 ka BP), Early Harappan (~8–6.5 ka BP), Early mature Harappan (~6.5–5 ka BP) and mature Harappan (~5–2.8 ka BP)"

And here is the conventional chronology

"Conventionally the Harappan cultural levels have been classified into 1) an Early Ravi Phase (~5.7–4.8 ka BP), 2) Transitional Kot Diji phase (~4.8–4.6 ka BP), 3) Mature phase (~4.6–3.9 ka BP) and 4) Late declining (painted Grey Ware) phase (3.9–3.3 ka BP). This chronology is based on more than 100 14C dates from the site of Harappa and nearby localities".

Here is the chronology Mr. Mehta presents:

The first line in the introduction section of the research paper makes it clear that all dates are presented in BP (Before Present). Yet Nalin Mehta in his article bungles up and without applying the necessary correction presents the chronology as representing dates in BC. The difference is 2000 years! For example, 5000 BP is 3000 BC.

Another big error he makes is lumping all the Harappan cultural stages into one mature phase spanning 8000 -2000 BC ! This gives an erroneous view of the evolution of Harappan society. The mature phase represents urbanization. The earlier cultural stages were rural antecedents represented by farming and pastoral communities and even earlier human settlements in this area. By terming the entire time span of Harappan culture as belonging to the mature phase, Mr Mehta gives an impression that Harappan cities were as old as 8000 BC. This is certainly not the case. This new study revises the mature phase of the Harappan culture from the accepted ~2600 BC-2700 BC (4700 BP) to ~ 3000 BC (5000 BP). This proposed revision at one cultural site should not be taken to mean that dates for cities like Harappa, Mohenjodaro, Dholavira will suddenly be changed to 3000 BC. Their chronology needs to be ascertained independently. As of now, large number of C14 and thermoluminescence dates have secured the age of these cities to be around 2700 BC or so.

One has to be careful with terminology. Mr Mehta uses dates as old as 8000 BP (wrongly presenting them as 8000 BC) to imply that the Harappan civilization is older than the Paraoahs of Egypt. Such a comparison is meaningless. These earlier dates represent a rural society. No doubt there was population and cultural continuity of these earlier people with the later urban phase, but you can say the same thing about pre-urban Egyptian and Sumerian cultures evolving into a full fledged urban civilization. There was a long pre-urban phase from 5-6 millenium BC in Eygpt and Sumer (synchronous to the Indus region) with central political consolidation and urbanism by around 3100 BC in Egypt when the first dynastic kings known as the Pharaohs seized power. In Sumer, the transition from rural to urban took place even earlier with cities like Uruk gaining prominence well before 3500 BC.

The differently named cultural stages of the Indus valley carry a specific meaning  in terms of societal complexity and cultural changes. You can't just call everything mature Harappan and then claim that the finding requires some kind of a fundamental rethink of Harappan society. 

As it happens, the dates presented in the paper that Mehta is ga-ga about are not new. Archaeologists have been aware of the alternate chronology presented by G.L Possehl for about 15 years now! In that sense there is nothing revolutionary about the chronology presented in this paper.

..rant over.


  1. The Indian media is not alone in its quest for excellence in garbled reporting of scientific studies. The BBC's reporting of science, especially areas close to linguistics, is legendary:

    1. Anon- thanks for the link.. media disease i guess :)