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February 14, 2019

The Vedic People: Their History and Geography

Filed under: History — Razib Khan @ 4:15 am

My boss leant me is copy of Rajesh Kochhar’s The Vedic People: Their History and Geography. It’s a short and dense book that covers many fields. I highly recommend it. As usual, don’t take it as gospel, but as a starting point. The author’s command of the scholarship so is impressive.

Love, oxytocin and evolution

Filed under: Evolution,love,oxytocin,science,valentines-day — Razib Khan @ 1:52 am
Gibbons form pair-bonds

On some level, most scientists would say that everything is reducible to material and mechanism. But to say that “everything is due to the swerve of atoms” doesn’t get us much further than the ancient Greeks, who were the first to elaborate on such materialist ideas philosophically.

At the other extreme from scientists are those humanists who assert that concepts such as “love” or “hate” are not reducible to scientific analysis and decomposition. In this framework, love and hate are both emotions which exist in a particular social and cultural context, and general systematic analysis may miss the forest from the trees.

But if physics does not offer answers beyond the trivial, a better understanding of behavior or mental characteristics can be obtained by looking at sciences such as cognitive neuroscience and evolutionary biology, which exist at a higher level of phenomenological complexity. Behavior comes from the mind, and the mind is an expression of the brain, which itself is shaped by evolutionary pressures.

Romantic love as an emotion then exists in the context of our evolutionary history, and that history likely has something to do with mating and pair-bonding. Our “reproductive fitness” is conditional on the very act of mating, and often survival is dependent on aid and help from others. For birds, monogamy is so common because both parents are often required to warm and tend to eggs. In mammals, in contrast, males tend to be less involved in provisioning for offspring. But there are exceptions.

An “alpha couple” among wolves

Wolves, and some primates such as gibbons and humans, tend to be monogamous. This is evident in the minimal difference in the size between the two sexes, as well as genetic data which shows that the “effective population size” of males and females over time has been in the same order of magnitude. That is, a reasonable proportion of both males and females contribute genes to the next generation.

Humans have extended childhoods

One reason that humans have elaborate emotions related to bonding seems to be that our childhoods are extremely long. This means that parents, and in particular the mother, develops a strong bond to their offspring, which is reciprocated. In the complex social systems of our species feelings of connectedness extend to kinship, and the bond between mates is solidified with romantic love and companionship. Love comes in many forms in our lineage, but it is clearly a feature and not a bug.

This is ultimately a consequence of genetics. The tendency toward prosociality and empathy seem to be heritable. That is, some of the variation of the characteristics within a population is due to variation in genes. This is clearest in prairie voles, where different species exhibit radically different behaviors in relation to bonding and mating, and also different genetic profiles.

Individuals with more “G” allele have more empathy

In humans, the neuropeptide oxytocin has been implicated in variation in characteristics such as empathy and bonding. This research began with relatively small samples, but a recent study with 1,830 individuals reports a single mutation with the OXTR locus is associated with variation in empathy. This is not entirely unreasonable in light of the fact that in the modern human population there are differences in personality, and dispositions, including empathy. The persistence of various personality types indicates that there’s no singular way in which one maximizes long-term fitness, but many alternative strategies (within limits).

Romantic love in terms of its biological basis may have a fundamentally material and evolutionary origin: a tight bond between parents results in a greater likelihood that offspring grow up to adulthood. It emerges from a complex set of neurobiological pathways, which themselves vary due to genetic factors from person to person.

But just as sugar is a molecule we understand but find still delicious, so the sweetness of love remains even after unmasking the underlying science.

Interested in learning where your ancestors came from? Check out Regional Ancestry by Insitome to discover various regional migration stories and more!

Love, oxytocin and evolution was originally published in Insitome on Medium, where people are continuing the conversation by highlighting and responding to this story.

February 13, 2019

The Insight Show Notes — Season 2, Episode 14: Love & biology

Filed under: Evolution,love,valentines-day — Razib Khan @ 6:51 pm

The Insight Show Notes — Season 2, Episode 14: Love & biology

This week on The Insight (Apple Podcasts, Stitcher and Google Podcasts)we discuss “love” from the perspective of an evolutionary biologist. More specifically, we had a wide-ranging discussion with Steve Phelps, a professor at the University of Texas in Austin. He studies the intersection of behavior, evolution, and neuroscience, with genetic tools.

First, we addressed whether love is a cultural invention of the last few thousand years. Particularly, of the West.

The reality is that love, and in particular romantic love, is a primal urge that likely existed in the environment of our “evolutionary adaptedness.” But its particularities are cultural. There is a lot of diversity “on top” of the basic source code. But there is a human universal we recognize.

We talked about inclusive fitness and the origins of love as an emotion in socialization. In particular, the common neurological and evolutionary origins of love in the context of parent-child, family, and partners.

A debate emerged about whether humans are ancestrally “monogamous” or “polygamous.” The terms differ in definition across discipline (genetics, behavior, anthropology), but the consensus seemed to be that we’re more monogamous than gorillas or chimpanzees.

There was much discussion of the literature on the association between empathy at the OXTR locus. Mostly commonly studied in voles, there are also suggestive results in humans. But much work needs to be done!

We talked Helen Fisher’s work in the neurobiology of love and attachment, and her excellent books such as Anatomy of Love.

Steve finished with a discussion on frequency-dependent selection, and how a diversity of behavior and disposition might be maintained.

Interested in learning where your ancestors came from? Check out Regional Ancestry by Insitome to discover various regional migration stories and more!

The Insight Show Notes — Season 2, Episode 14: Love & biology was originally published in Insitome on Medium, where people are continuing the conversation by highlighting and responding to this story.

A brain warped by reading

Filed under: medium,Podcast,podcasting,Writing — Razib Khan @ 1:05 am
Stanislas Dehaene’s Reading in the Brain: The New Science of How We Read is an excellent book because it shows how we reuse preexistent cognitive architecture to extend our capacities through cultural creativity. There is, for example, a part of the brain that is localized toward recognizing the shapes of letters to allow immediate “sight […]

February 12, 2019

Why Charles Darwin matters

Filed under: darwin,Evolution,science — Razib Khan @ 2:11 am

Charles Robert Darwin was born on February 12th, 1809. He was the son of a prosperous and prominent lineage. His grandfather, Erasmus Darwin, was a physician and public intellectual. Like his more famous grandson, the elder Darwin was a natural philosopher who propounded theories of evolution. On his mother’s side, Charles Darwin was the grandson of the manufacturer Josiah Wedgewood. If Erasmus Darwin reflected the intellectual currents of England during the late 18th century, Wedgewood illustrated the rise of the merchant class with the industrialization of Britain.

Growing up in comfortable circumstances, Charles Darwin had many opportunities to succeed, or fail. His university career was checkered at best. At one point it seemed likely that he would become a clergyman in the Church of England, satisfying his interest in the natural world as an avocation.

Life had different plans for him. He famously went on a voyage around the world, and his observations of the geology, flora, and fauna, fed into his later theories. But the truth is that the immediate consequence of Darwin’s travels was a book, The Voyage of the Beagle, which made him something of a minor celebrity in Victorian England. Even without The Voyage of the Beagle his name would likely have been noted in the pedigree of the prominent Darwin-Wedgewood family.

If Charles Darwin had never published The Origin of Species, history would have remembered him, albeit as a minor figure of the 19th century.

But Darwin did publish The Origin of Species. And after this, he published other books, most famously The Descent of Man. But Charles Darwin’s fame rests primarily on a single book published in 1859, whose full title was On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life.

Charles Darwin the man led a fascinating and full life. His lineage was colorful, his times were exciting, while his marriage was loving and passionate. Charles Darwin had enough texture and tension within his life that feature films can easily revolve around him as a character. He was a man in full.

But we are talking about Charles Darwin today because of the science which he assembled and presented within The Origin of Species. Though evolutionary ideas had been around since the time of the ancient Greeks, it was Charles Darwin who brought the idea to life through a plausible, compelling, and ubiquitous dynamic and underlying mechanism in the form of adaptation through natural selection. There were earlier evolutionary thinkers in the 19th century, but the reason that we use the term “Darwinism” interchangeably with evolutionary biology is that the model presented in The Origin of Species laid the foundation for the whole scientific discipline.

Science is not a single idea. It is not a hunch. It is the assembling of observations, the construction of theory, and the generation of predictions. With Alfred Wallace, Charles Darwin presented to his contemporaries the hypothesis that natural selection was the motor which drove the riotous diversification of form and function around us in the living world.

The development of genetics as field after 1900 revived Darwinian evolutionary biology as the study of the process of natural selection became a core element of the field of evolutionary genetics. Though others had proposed the tree of life and common descent, it was Darwins’ ideas of how that tree diversified which transformed what had been a stale description into a dynamic representation of what we now call evolutionary process.

It is true that despite the fertility of his mind many scientists today within biology do not read Darwin’s original works. But that is because his conjectures and certainties are laced through fields, part, and parcel of the axioms which are taken for granted by working researchers.

Today all biologists implicit stand on Darwin’s shoulders to see further and more clearly.

Interested in learning where your ancestors came from? Check out Regional Ancestry by Insitome to discover various regional migration stories and more!

Why Charles Darwin matters was originally published in Insitome on Medium, where people are continuing the conversation by highlighting and responding to this story.

February 11, 2019

What to read if you don’t want to read Guha

Filed under: History — Razib Khan @ 8:17 pm

In the podcast with Kushal Mehra he made an offhand comment that it was strange that conservative American intellectual Ben Shapiro was reading India After Gandhi to understand his country. Mehra’s confusion is simply that Shapiro is on the Right, but he is reading from the perspective of Indian Left to understand India. Though probably hyperbolic, perhaps it would be like a Hindu nationalist reading Howard Zinn’s A Peoples History of the United States to understand America.

I know there are issues India After Gandhi. My friend Reihan Salam thought that Amardeep Singh was entirely too uncritical when he blogged the book many years ago. Since I have no read the book I will not hazard to offer an opinion.

But, the question then remains: what books on Indian history should an American read to offer up some balance? This is a live issue, as an American conservative friend was himself considering reading  India After Gandhi before being taken aback by Mehra’s comment about Shapiro and his reading habits.

Please leave book recommendations!

Open Thread – Brown Pundits

Filed under: Open Thread — Razib Khan @ 7:03 pm

Please keep the other posts on topic. Use this for talking about whatever you want to talk about.

On the difficulties of cross-cultural communication

Filed under: Blog,Comments — Razib Khan @ 3:34 am

I speak English. But I speak a certain type of American English. I’m brown. But my culture is American.

On a blog like this, these structural problems give rise to particular issues. I actually saw it on the old Sepia Mutiny blog first. Indian English is a distinct dialect not only in accent and lexicon but also in idiosyncrasies in its idioms.

When we speak and write to the audience of this weblog, Indian and American (or British) audiences may actually infer different implications of the things we say. The easiest way to illustrate this is the use of the word “secularist.” The word is rich and pregnant with connotation and association for the Indian audience, but not so much for the American one, where it denotes something clear, distinct, and delimited. For the Indian audience, I avoid using the word “secularist” and “secular”, because I don’t want to get involved in a stupid argument that I have a marginal investment in.

I really can’t fix this issue of semiotics and linguistics. Sometimes confusions will ensue, and I will point out the reason.

But, there are two problems with some Indian commenters of this weblog that I want to highlight:

  1. Throwing up a “wall of text” in lieu of a concise argument.
  2. Obvious bad-faith posturing.

On my posts, if you engage in this behavior I may just delete your comments without warning. Those of you who have engaged in #2, I know exactly who you are, and I may delete your comments without warning too. Talking with a friend who is Indian but not raised in the United States, it could simply be that this behavior is taken for granted as normal by Indians (Hindu nationalist repurposing of SJW talking points without any shame suggests to me that this may be the case). That’s fine. But not on my posts.

I am not going to manage the posts of others. So perhaps my posts will become deserts of commentary. I am at peace with that.

Open Thread, 02/11/2019

Filed under: Open Thread — Razib Khan @ 2:57 am
Rereading Nature’s Metropolis: Chicago and the Great West, and it’s striking how different Americans today are in relation to development and economic growth. Yes, we want to be richer, but in large parts of the country, there is a strong tendency to want to bake incumbency advantages into the cake. Texas and Florida still retain […]

February 9, 2019

BrownCast Podcast episode 14: conversation with a Carvaka

Filed under: Open Thread — Razib Khan @ 8:49 pm

Another BP Podcast is up. You can listen on LibsyniTunes and Stitcher. Probably the easiest way to keep up the podcast since we don’t have a regular schedule is to subscribe at one of the links above. You can also support the podcast as a patron (the primary benefit now is that you get the podcasts considerably earlier than everyone else…this podcast has been up for nearly a week on the patron page).

As far as show notes go, just check out Kushal Mehra’s YouTube page.

February 8, 2019

We are all Aryans now

Filed under: Aryans,Genetics,History — Razib Khan @ 11:59 am

Last year I contributed a chapter to a book soon to be published in India, Which of Us are Aryans? In answer to the question, the straightforward answer is that almost all of us are Aryans. That is, the thin but persistent layer of Indo-Aryan (“steppe”) ancestry is present across the subcontinent. In higher fractions among Brahmins and Kshatriyas than in Dalits, in the northwest than the southeast, and among Indo-European speakers than Dravidians. But this ancestral component and its cultural correlates are found across southern Asia.

Secondarily, there has been some discussion about the negative valence in the West about the term “Aryans.” In particular, its “cultural appropriation” by German Nazis by way of Theosophy and various spiritual and quasi-spiritual movements in the early 20th century.

As an American to see the word “Aryan” bandied about like this is strange and a bit uncomfortable. But there are now more than 1 billion Indians, so I don’t believe we in the West are a position dictate in terms of the lexicon that we borrowed from Indians in the first place, often without clear attribution (most Americans and Europeans would be surprised that “Aryan” is an Indian and Iranian term).

February 7, 2019

BrownCast Podcast episode 13: conversation with a Hindu nationalist

Filed under: Podcast — Razib Khan @ 10:03 pm

Another BP Podcast is up. You can listen on LibsyniTunes and Stitcher. Probably the easiest way to keep up the podcast since we don’t have a regular schedule is to subscribe at one of the links above. You can also support the podcast as a patron (the primary benefit now is that you get the podcasts considerably earlier than everyone else…this podcast has been up for nearly a week on the patron page).

I asked our interlocuter for some reading material. Here’s what he suggested:

Essentials of Hindutva

Hindu Society Under Siege

Who is a Hindu?

– The Sarva-Darsana-Samgraha Review of the Different Systems of Hindu Philosophy

Obviously, there wasn’t going to be any resolution after an hour and a half long conversation. Instead, questions and confusions were clarified. Disagreements were aired. That being said, I did leave the discussion crystal clear about what Pinaka opposed, rather than what he supported. At least in the specifics. I would hold that one reason that this is so is that it is easier to say what Hindu culture and religion is not more than what it is.

The ghost of empire and the origin of all repression

Filed under: Culture,Noble Savage,Sexuality — Razib Khan @ 9:39 am

The New York Times published an op-ed, How British Feminism Became Anti-Trans, where India implicitly makes a showing:

It’s also worth noting that the obsession with supposed “biological realities” of people like Ms. Parker are part of a long tradition of British feminism interacting with colonialism and empire. Imperial Britain imposed policies to enforce heterosexuality and the gender binary, while simultaneously constructing the racial “other” as not only fundamentally different, but freighted with sexual menace; from there, it’s not a big leap to see sexual menace in any sort of “other,” and “biological realities” as essential and immutable….

These views are very common on the cultural Left. When progressive social activists make these assertions, and I argue that they are factually wrong, I’ve often encounter surprise and annoyance. There are two things I suspect going on here:

– These people are not genuine propagandists, they actually believe their own fictions. Faced with facts that are novel to them don’t know how to react. They live in a factual bubble where it is taken for granted that the idea of binary gender as a dominant paradigm was introduced by Westerners to South Asians, whose own conceptions were fluid, open, and tolerant.

– The facts of the history of non-Western cultures are fundamentally irrelevant because they exist only to support narratives relevant within Western cultures. Those narratives and the trajectory of Western culture is their true passion. Their fundamental Eurocentrism means that falsehood about non-Western cultures is not particular of great concern. That is not “their history.” Minor details to be ignored and brushed aside.

Gibbon famously asserted that the Pope, and implicitly the Roman Catholic Church, was the “ghost of the Roman Empire.” A living, breathing, vestige of an institution and society long gone. Much of modern Western Left social progressivism, informed by critical theory and post-colonialism, is a ghost of 19th and 20th-century empire. It is the warped inversion and reflection of Western chauvinism and populism.

It is highly peculiar to me that on the precipice of the 21st Asian age Western intellectuals bask and wallow in the reflected glory of Victorian-era empires as if they are determinative of all the goings on today. Part of this is surely due to the reality that intellectual currents are lagging indicators, and empires always persist longer in memory and self-regard than in reality. And part of it is the human needs for “noble savages” and “pure” Others against which their own sins may be measured and contrasted.

February 6, 2019

Dreaming of billions of genomes

Filed under: Genetics,Genomics,Privacy — Razib Khan @ 8:43 pm

In the year 2000 scientists finished the draft of the complete human genome. The “reference” for what came after. Even ten years earlier some researchers were questioning the feasibility of any such project! In the early 1990s, many assumed it would be many decades before the first human genome was mapped. What changed?

Technology invaded science. The first human sequence cost three billion dollars. Today one can be had for $1,000. In other words, a genome was three million times more expensive just 20 years ago.

An Illumina sequencer

Instead of the laborious process of tracing inheritance patterns through visible markers, modern genomics utilizes the molecular nature of DNA to enable automation and computation to “read” the full sequence. In less than 20 years we’ve gone from a single human genome sequence to hundreds of thousands of whole genome sequences, and tens of millions of samples which have undergone high-density genotyping using “SNP-array” technology.

Though the human genome is three billion bases, only a small proportion of it codes for genes, and an even smaller proportion holds any variation of interest in a population genetic sense. The millions of genotypes in the databases of private consumer genomic firms may only capture a small number of genetic positions, between 100,000 and one million, but this small number is enough to draw many important conclusions. In particular, what common diseases you are at risk for, and what part of the world your family is likely from, and who your relatives are.

In other words, probably 90% of the things you would want to know about your genetics can be inferred from 0.03% of your whole genome! Today private companies are sitting atop a pot of potential gold because the genome doesn’t change over your lifetime. It is only an appreciating asset as time progresses, as more research unveils details of mechanism and associations.

You are being watched!

Within twenty to thirty years it is likely that a billion human genomes will be sequenced. The field will have fully transitioned from basic science to information technology. And as with any information technology, privacy and data sharing will be important things to consider. It is likely that some governments, like that of China, will have total access to their citizens’ data, while others, such as those of the European Union, will limit access.

But even without top-down invasion of privacy, the proliferation of databases and sequences will mean that one’s genetic information will be shared like credit scores across vendors. And just like with credit scores and histories, there will be data breaches. And while credit scores as ephemeral, your sequence is permanent.

Total strangers may have access to your disease risks, your relatives, and your heritage. Things today which is guarded privately may become totally transparent to anyone who wants to look unless precautions are taken.

The decisions we make today will have consequences for future generations. This applies to individuals, corporations, and the government.

Interested in learning where your ancestors came from? Check out Regional Ancestry by Insitome to discover various regional migration stories and more!

Dreaming of billions of genomes was originally published in Insitome on Medium, where people are continuing the conversation by highlighting and responding to this story.

The Insight Show Notes — Season 2, Episode 13: Is the FBI Watching Your DNA?

Filed under: Genealogy,Genetics,Privacy — Razib Khan @ 2:30 pm

The Insight Show Notes — Season 2, Episode 13: Is the FBI Watching Your DNA?

This week on The Insight (Apple Podcasts, Stitcher and Google Podcasts)we discussed the controversy that has erupted around Family Tree DNA and genetic privacy. We talked to Judy Russell of The Legal Genealogist and genetic genealogist Debbie Kennett, both longtime observers of the industry and science.

BuzzFeed broke the story. Then Bennett Greenspan of Family Tree DNA responded to their customers. Eventually, the story spread to The New York Times.

The CEO of Family Tree DNA, Bennett Greenspan, is a genetic genealogist himself. His company began as a way to pursue his passion after other successes in business. He talks about this video talking about genealogy and DNA.

This episode is a follow-up in many ways to the Golden State Killer incident.

Because of the international scope of this industry, we extensively discussed the GDPR, the European General Data Protection Regulation.

Interested in learning where your ancestors came from? Check out Regional Ancestry by Insitome to discover various regional migration stories and more!

The Insight Show Notes — Season 2, Episode 13: Is the FBI Watching Your DNA? was originally published in Insitome on Medium, where people are continuing the conversation by highlighting and responding to this story.

February 5, 2019

Open Thread – Brown Pundits

Filed under: Open Thread — Razib Khan @ 12:02 pm

Please keep the other posts on topic. Use this for talking about whatever you want to talk about.

Just a note, that two future podcast episodes are up in the patron’s page. One of them on Indian military history and another a discussion with a Hindu nationalist. We plan on doing follow-ups to both.

February 4, 2019

Open Thread, 02/04/2019

Filed under: Open Thread — Razib Khan @ 5:18 pm
Most of you know about The Insight, my podcast with Spencer Wells. Some of you may not know about the BrownCast, associated with the Brown Pundits. I’m on about two out of every three podcasts, but it’s a group effort. We cover a diverse array of topics. The latest episode was a conversation between myself […]

February 2, 2019

The religious and genetic structure of Bengal & Partition

Filed under: Genetics,Partition,Religion — Razib Khan @ 2:54 pm

I was emailing with a friend of mine about population genetic history and Southeast Asia. I mentioned offhand that there is an east to west cline of Tibeto-Burman ancestry in Bengal. He expressed surprise, assuming Partition had scrambled everything.

As most readers of this weblog know, Partition was less traumatic for Bengal than it was for Punjab. The violence was less extreme, and the population movement also not as massive. And yet looking at the religious map it is clear that some sorting has occurred. The proportion of Hindus in the region that is now Bangladesh has gone from ~25% to about 10% over the past 70 years, or three generations. Though some of this is due to differences in fertility, the main driver has been migration of Hindus out of East Pakistan, and later Bangladesh. In contrast, there has not been much of a reciprocal migration of Muslims into Bangladesh.

This results in a peculiarity when I receive genotypes from people of Bengali origin: a large minority of people of Hindu background mention that one or both of their parents have origins in eastern Bengal, what is not Bangladesh. In contrast, I have never received a gentoype from someone who tells me that their family migrated from western Bengal into Bangladesh.

The genetic consequence is simple: there is a larger variance of East Asian ancestry in West Bengal than East Bengal because of more mixing in the west than the east. In contrast, one could probably infer the extent of the migration simply by doing genetic analysis and not looking at Census data!

February 1, 2019

BrownCast Episode 12: The global China, with Carl Zha

Filed under: Podcast — Razib Khan @ 12:34 am

Another BP Podcast is up. You can listen on Libsyn, iTunes and Stitcher. Probably the easiest way to keep up the podcast since we don’t have a regular schedule is to subscribe at one of the links above. You can also support the podcast as a patron (the primary benefit now is that you get the podcasts considerably earlier than everyone else).

If you aren’t in a position to be a patron, please give us 5-star ratings and a positive review!

After this podcast was recorded and edited Carl Zha Informed informed me that he is no longer doing CLASH! and rather is starting a new podcast: Silk and Steel. This is actually the first post on Silk and Steel as well. A “cross-over.”

First, Carl and I talked about the problems with the media representation of China. He did offer that The Wall Street Journal, in particular, gets it right more often than not (which made me happy since I’m a subscriber).

We also discussed a bit our disparate backgrounds.  And how Carl’s experience gives him a window onto both America and China. He arrived in the United States in 1990 as a tween.

We also talked about whether China was a colonialist power in places like Africa. Carl objected to the simple analogy, seeing as how China’s relationship with other nations is very economic and pragmatic, rather than rooted in an explicit imperial and supremacist agenda.

I asked Carl about the growth of Christianity within China and in the Diaspora. Carl thinks the Diaspora is different because in many nations Christianity allows the Chinese to cohere and become rooted. It enables the growth of community institutions. In China that is not as necessary, so he believes it will be a small minority religion like in Taiwan.

We talked a lot about Uygurs, Hui, and ethnic relations in China. And the pervasiveness of casual racism among many Asians.

This weekend I will be recording a podcast with someone sympathetic to Hindu nationalism. I don’t have a fixed set of topics. Omar will also be hosting a podcast on military history. And, I have gotten a commitment from a friend who is a screenwriter in Hollywood to talk as well.

January 30, 2019

How ancient DNA illuminated the dark cave

Filed under: Ancient DNA,Paleoanthropology,science — Razib Khan @ 9:23 pm

Unfortunately, we do not have a time machine, nor is there any likely possibility of any such thing in the near future. The laws of physics are what they are. That is why those of us who are interested in the human past must make recourse to disciplines such as history, archaeology, and paleontology.

But all of these have their limits. History’s reliance on the written text means that there is a bias toward the records of the powerful and privileged because for much of history writing was the purview of elites. Archaeology focuses on material remains and artifacts, but there is only so much insight one can squeeze from pottery shards. Finally, paleontology must rely on bones which are very rare and do not provide a fully-fleshed picture of human life (literally!).

Of course, these methods improve over time. The decipherment of cuneiform in the 19th century opened up the pasts of the Babylonians, Akkadians, and Sumerians. In the 1950s the decipherment of Linear B meant that historians could confirm that the Mycenaean peoples of the Bronze Age were Greek-speakers. Radiocarbon dating transformed the ability of archaeologists to produce chronologies of cultural change over time at any given location with incredibility certainty. Finally, paleontologists have been able to utilize modern technology to “scan” fossils and so obtain much more information from any given sample than was possible in the post.

Into this landscape stepped ancient DNA. Analysis of genetic remains and material dates back to the 1990s, pioneered by Swedish paleogeneticist Svante Pääbo. But Pääbo’s work really came to the attention of the mainstream when his team sequenced the whole genome of a Neanderthal in 2010. Consider how amazing this is in light of the fact that the draft of the first human genome was only completed ten years earlier!

And it turned out that the Neanderthal genome had surprises in store for paleoanthropologists which they had not anticipated. For decades the relationship between Neanderthals and modern humans had been debated. The primary question being whether the former were ancestors of the latter. Or not, as was the orthodoxy in 2010 in much of paleoanthropology!

Pääbo himself held to this orthodoxy, and earlier work sequencing the mitochondrial DNA passed from mother to daughter, confirmed that Neanderthals were distinct from modern humans. No modern humans seem to carry a Neanderthal mitochondrial lineage. Case closed.

But the data had other plans. When the researchers compared the genome of the Neanderthal to that of modern humans, they found that modern humans were very different. This was to be expected. But, they noticed a peculiarity in the relatedness: modern humans outside of Africa were all somewhat closer to Neanderthals than modern humans within Africa. Assuming that modern humans descend from a population that expanded out of Africa relatively recently, the most plausible explanation for this pattern is that some of these non-Africans mixed with Neanderthals in their migration outward.

Denisova Cave

The ancient genome changed everything because now there was a definite benchmark for comparison, rather than all the indirect attempts that had been performed in the past. The ancient DNA was a game changer, confirmed by the finding later that year that remains from Denisova cave in Siberia belonged to a previously unknown lineage of human, closer to Neanderthals than modern peoples. It turns out this mysterious population also contributed ancestry to the peoples of Papua New Guinea, far to the south and east. So a single ancient genome transformed our understanding of the past, and shed light on patterns in the present.

Now, it isn’t as if geneticists were not using their techniques to make inferences about the past for decades. The “Out of Africa” model rested on genetic inferences, looking at variation in living people, and concluding from that that the ancestry of modern humans likely derives from an ancient African population. At such a broad level a method which relied on modern variation was sufficient. The results have held up. But when it came to narrower questions the methods which looked at the “tips” of the phylogenetic trees, the extant populations today, have been far less successful.

We know this because ancient DNA from the past 40,000 years has shown that there were massive population turnovers and mixtures all across the world. Using modern DNA to make projections of the past rely on assumptions of geographic stability of human groups…which turn out to be wrong. If one thinks of the human past as a phylogenetic tree, ancient DNA allows one to fill in “nodes” upstream of the “tips” of the tree. This resolves ambiguities, confusions, and corrects for mistakes in assumptions.

Ancient DNA cannot tell researchers “who” a people were. What language they spoke. Or how they lived. What it can tell you without debate is how people were related to each other in the past, and how they are related to people today.

We know, for example, that very few of the ancestors of modern Europeans derive from the people who drew the enigmatic cave paintings of the Upper Paleolithic. We also know that no modern people descend from the Cro-Magnon bands who replaced Neanderthals in Europe. These artistic creations are in some meaningful way the true legacy of these lost peoples.

Humans are one of the most mobile mammals, occupying six of the seven continents by 10,000 years ago. The tools, the technologies, of ancient DNA are another quiver in the arsenal of prehistorians. The migration of peoples is not everything, but it is an essential thing because without migration we wouldn’t be the most successful large mammal of the past 60 million years.

Interested in learning where your ancestors came from? Check out Regional Ancestry by Insitome to discover various regional migration stories and more!

How ancient DNA illuminated the dark cave was originally published in Insitome on Medium, where people are continuing the conversation by highlighting and responding to this story.

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