Tag Archives: Human Evolution

Nepal in 1950s


Nepal is a small but ethno-linguistically rich Himalayan country that consists of eight of the world’s tallest mountains. Despite being small, Nepal is home to over one hundred languages. Where did these people originate? What are their histories? Unfortunately, due to scanty archeological and historical data, we do not know much about the Nepali linguistic communities.

Understanding population distribution i.e., where people live may tell us important things about origins and histories of a particular population. Basically, dense localization of a population in a particular area may suggest the population’s historical territory. Similarly, population spread may indicate migratory patterns of certain populations. If multiple populations harbor the same area, it is likely that gene flow between such populations may have occurred in the past.

Thus, to learn about the histories of different Nepali language communities, I looked at the census data from 1952-54, which is the first reliable census of Nepal. I obtained the data, formatted it, and cleaned it up a little bit.For this census, Nepal was divided into 9 census regions and 67 census districts (Fig.1). Although data for district level is available, I will focus on the regional data for this article.


Figure 1: Nine census regions in first Nepali census (1952-54 A.D.)

According to the census data, there were 8,473,478 people native to the 28,770 villages and cities in Nepal. Only five cities had more than 5000 inhabitants: Kathmandu (107K), Lalitpur (42K), Bhaktapur (32K), Nepalganj (11K), and Birganj (10K). Interestingly, Thimi, a town between Lalitpur, Kathmandu, and Bhaktapur also had 8.7K people. Migration rate, defined as people not present in their ancestral homes for six months or more, was negligible: 2.6% for the entire country and between 0.06-4.3% for the nine census regions. This makes sense because Nepal was very remote until recently. The first highway was constructed in 1960s before which traveling was probably very difficult, therefore rare. Closed to the western world until 1950, first available reports have also described Nepal as remote and rural and difficult to travel.

The negligible migration rates indicate that most Nepalis lived in their ancestral villages. Therefore, this census data may be useful in understanding the historical population structures within Nepal. Hence, I first looked at population density in each census region (Fig, 2).


Figure 2: Population density in the nine census regions in 1952-54

In the first glance, most populous region in Nepal was Western Hills and the least populous was Western Inner Terai. However, after accounting for geographical area, Kathmandu valley, which consists of three towns: Kathmandu, Bhaktapur, and Lalitpur, was remarkably the most populous region within Nepal consisting of 5% of the entire population. Around 45% Nepalis lived east of Kathmandu valley, Western Hills comprised of 40% of the population, and 61% of the Nepali populations lived in the Hills (Eastern and Western Hills combined). The least populated region in the country was Far-Western Terai, likely because it was covered with dense malaria infested jungles.



Figure 3: Population size of different ethnolinguistic communities within Nepal in 1950s

From the data, major language groups appear to be Nepali, Maithili, Tamang (Lama), Newari, Tharu, Magar, Rai, and Limbu. Although currently over 100 languages are recognized in Nepal, in the 1950 Census reported around 36 language groups (Fig.3), probably in an effort to not contradict Prithvi Narayan Shah’s Divyopadesh  in which he has proclaimed that Nepal is a common ground of 4 varnas and 36 jaats. Many of the smaller language groups in Terai have been lumped into “Pradesh dialects.” Also, several of the High Himalayan languages recognized today are missing. Because the census was conducted by traditional revenue collectors, known as  jimmewals and patwaris, perhaps the Rana government thought that the burden of visiting the remote High Himalaya was not worth the negligible revenues it would extract from its inhabitants. Therefore, it is reasonable to assume that these populations were not included in the first Nepali census of 1952-54.

My ultimate goal was to find clues about population histories of different ethnolinguistic groups within Nepal. Therefore, I used the “mother tongue” data to first see if I can learn anything about where different language communities lived in 1950s.



Figure 4: Ethnolinguistic diversity within Nepal in 1950

Figure 4 shows what proportion of population in each census region is contributed by which language community. For example, about 55% of population in Kathmandu were Newar, 40% were Nepali speakers, and the remaining 5% were Tamang. Although considered natives of Kathmandy valley, appreciable proportions of Newars were present outside of Kathmandu valley in Central Terai (5%) and Eastern Hills (4%). Newars were absent in all Terai regions.

The census clearly shows that Terai was populated by various non-Nepali speakers. Even in 1950s, it is clear that Nepali speakers were widespread in Nepali Hills and Inner Terai, but were also virtually absent (<5%) from all of the Terai (Fig.4). Given the low migration rates, it is likely that the populations that lived in certain parts of Terai in 1950 were native to that region. For example, the majority of populations in West-Inner Terai (57%) and Far-Western Terai (60%) were Tharu, a tribe that is indigenous to dense, malaria-infested, impenetrable jungles, also known as chaar-kose jaadi that decorated Terai until very recently. Indeed,  Danagaura Tharu (Banke, Bardiya, Dang, Surkhet), Kathariya Tharu (Kailali), and Rana Tharu (Kailali and Kanchanpur) are indigenous to FW Terai. Tharu presence is also strong in  Mid-Western Terai (20%) and Central Inner Terai (12%). Indeed, Chitawania Tharu are known to be indigenous to Chitwan, Bara, Persa in Center Inner Terai. The presence of Tharu is appreciable as well in East Inner Terai (6% of the population in Sindhuli and Udayapur), perhaps due to large populations of Kochila Tharu in this region. They are virtually absent in Kathmandu valley and in the Hills but interestingly, also in the Eastern Terai, which was mostly populated by Maithili speakers, perhaps because this region was once the capital of an ancient Maithili kingdom of Videha.

Tamang and Magar communities were widespread in Eastern as well as Central Nepal. Surprisingly, 33% of Nepalis in Central Inner Terai (Chitawan, Chisapani Garhi, and Nawalpur) were Tamang, although Tamangs were also present in Eastern hills and perhaps even in the high-altitude regions in the East. After Nepali and Tamang speakers, Rai (13%) and Limbu (8%) were the most populous groups in the Eastern Hills whereas  Magar were the third most populous in East-Inner Terai (12%).

Although this data indicates that Eastern Nepal was more diverse than Western Nepal, it is biased against the smaller language communities. For example, almost all of the 14,261 Chepang lived in the Central Inner Terai but they only comprised 6% of the population. Many other language communities have much smaller population sizes (Fig.3). Hence, to know the whereabouts of smaller language communities, I asked what proportions of speakers lived in each census region. In other words, I asked how each language group was distributed across different census regions (Fig.5).


Fig 5: Distribution of language families within Nepal in 1950

This figure clearly shows that many smaller language communities are localized to a particular region, especially in the Hills and Terai of the East. About 60% of Nepali speakers were present in Western Hills, indicating that Nepali speakers were originally residents of Western Hills and later spread rapidly to comprise the majority of populations in many other census regions (Fig 3). Although this is consistent with previous reports of rapid Khas migrations within Nepal, it is important to realize that this migration must have happened steadily over several generations because migration rate throughout the country was very low.

Eastern Hills appear to be very diverse along with Eastern Terai.  Many smaller language communities such as Jirel, Thami, and Sunuwar appear to be residents of Eastern Hills. Although Maithili is the dominant population in Eastern Inner Terai, Jhangar, Dhimal, Bhojpuri, Rajbanshi, and Satar also appear to be restricted to this region. It would be interesting to see when different populations arrived in this region of Nepal and whether any gene flow among these populations have occurred.

Also interesting is the Majwari population, which is present discontinuously in Eastern Terai and  Mid-Western Terai. Who are the Majwari peoples? How and why they moved within Nepal remains to be understood. Similarly, Sherpa seem to have two distinct populations: a strong presence in Eastern Hills and a moderate one in Western Hills. Danuwar also appear to have spread from Eastern to Central Nepal.

This data has shown that smaller language communities in Nepal have historically localized to particular regions whereas larger populations have moved around. However, there are certain populations that present in Eastern and Western Nepal but not in the middle. When did these populations migrate into separate regions? Given migration was negligible in 1950s, did these populations migrated in ancient times? Did they originate from the same ancestral population? How long ago they split? These are some interesting questions that need further work.



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Bonobo toolmaking hints glimpses of “cutting edge” stone age technology

This is really cool as human ancestors, many millions of years ago, my have started making tools in very similar fashion. Here is the Roffman et al. PNAS paper that describes the findings in detail.

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Genomics for future anthropologists & archeologists

An awesome use of genomics and proteomics in archeology and paleopathogenomics (yes I just invented the word!)

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Visualizing biology: from conception to birth, cell division, and more

Visualization helps in learning anything. In biology visualization has traditionally been done using pictures or posters (right).
From conception to birth. But that is so 1970s. In the technocratic future, where lullabies are delivered via iPod and iPads are norm in kindergarten, figures or posters wond do any good. Kids would hate to learn from static images….they need videos! And if you are making videos, you might as well use real data…and Alexander Tsiaras does exactly that. Using advanced technology on real pregnant women he captures images of life from conception to birth. Mes merizing!

Okay, let’s take it to a molecular level now. Let us look at structure of DNA, cell division, and molecular machinery of cell division:

Cant have enough? Visit Drew Berry’s page.

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Another example of ERV’s role in evolution

To end a royal dynasty, one has to eliminate its generals: this was the lesson of a Chinese movie I once watched in Netflix. Similar strategy is adopted by ERVs.
In a recent Plos Biology article (click here for a good summary for general audience) the authors identify MAVS, a protein produced by mitochondria (the general) that ignites immune response to protect the human cell (the Royalty) from Hepatitis-C virus (HCV). Three unrelated primates have the exact same non-synonymous mutation in the MAVS gene that  potentially alters the protein’s structure making it untouchable by the HCV particles. Unfortunately, humans, the primary host of HCV, do not have that mutation thus are relatively easily conquered by HCV. Sucks!
VERY INTERESTING is the presence of that same mutation in three different species: the authors apparently conclude it is a convergent evolution. However, this finding is in stark contrast with studies in yeast where convergence occurred at genic and network level but not at SNP level. Also, population genetics theories also find it very unlikely. Think about it, what is the probability that exactly same mutation would occur in three species branch AND SNP gets selected in all three branches? MINISCULE.
Could it be more plausible that the particular mutation existed in low frequencies in the common ancestor of all the primates and was readily available in all three branches at the time HCV like virus was active and quickly got fixed in the population? That particular virus probably did not infect humans (and other primates that do not have them) so they lost the mutaiton due to drift. Just a thought…

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Who were the Neanderthals?

Neanderthals, man’s closest relatives have excited many scientists for decades. In the past there have been many hypothesis and myths about Neanderthals by virtue of which, they have been portrayed as barbaric hominins that lacked culture. However, recent reports suggest Neanderthals were culturally sophisticated hominins that interbred with humans outside Africa. Here, I attempt to congregate scientific papers that debunk the myths about Neandethals. This is a work in progress and any additional articles about Neanderthals from the readers is highly appreciated.

Listen to NPR podcast on Neanderthals vs. Humans (7:35 onwards in the podcast) that discusses human brain development.

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Sperm: The Evidence for Evolution?

“This is the first clear evidence that suggests our ability to produce sperm is very ancient, probably originating at the dawn of animal evolution 600 million years ago,” said Eugene Xu, assistant professor of obstetrics and gynecology at Feinberg. “This finding suggests that all animal sperm production likely comes from a common prototype.”

This week’s journal Nature Research Highlight section features an article originally published in PNAS that demonstrates that some species of promiscuous hermaphroditic flatworms have “a variety of sperm shapes”. The ejaculate containing sperms are sucked by these worms after sex and only those sperms that have “pair of long bristles emerging at the mid-point and a tail resembling a paint brush” can anchor themselves in “the female orifice after copulation, preventing the sperm from being sucked out.” This is one example of adaptive evolution in these worms to select for those sperms that can quickly implant themselves in the female reproductive system such that they have higher chances to produce a zygote.
Figure obtained from Nature

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