Guess values, Priors and Science

Wikipedia defines Guess value as

“In mathematical modeling, a guess value is more commonly called a starting value or initial value. These are necessary for most optimization problems which use search algorithms, because those algorithms are  mainly deterministic and iterative, and they need to start somewhere.”

I am not an intuitive mathematician (nor an unintuitive one for that matter), but I have appreciated the importance of good guess value or nominal value developing software that uses computational geometry.

Yesterday I read this excellent long piece- The 60-Year-Old Scientific Screwup That Helped Covid Kill . Personally, I had been convinced by the Aerosol spread theory since I read these two pieces back in the Summer of 2020.

How Coronavirus Infected Some, but Not All, in a Restaurant

How coronavirus spread from one member to 87% of the singers at a Washington choir practice

As a result, I have spent the better part of the previous 14 months wondering “why is the scientific community so slow in accepting potential aerosol dispersion of coronaviruses”. They say science progresses one funeral at a time, but since Jan 2020 we have had far too many funerals that should have sped up the progress. Ever since I read this piece – The “noble lie” on masks probably wasn’t a lie I had been spending limited time I had, browsing through old papers on the spread of respiratory illnesses to disappointing results. The wired piece helped deepen my understanding of how we may have got here. Where the 5-micron boundary for aerosols came from is an extremely fascinating story. Maybe we can expect some Netflix documentary or a long-form book on this issue in the near future.

This entire episode appears exceedingly similar to the Dietary Fat is the villain dogma. Gary Taubes in his books – Good Calories, Bad calories and A Case against Sugar, has described this debate extremely well. As a video suggestion, I would recommend the youtube channel – What I have learned. In retrospect what seems appalling is how the scientific community basically accepted the faulty and weak fundamentals of the Fat theory – as initiated by Ancel Keys and propagated by hundreds after that. Ditto for the demonization of cholesterol and numerous other food items – including milk.

7 country study of Ancel Keys.

From these two examples at the very least, I would conclude the disproportionate importance of Priors and the outsized impact they have on the journey of academic and peer-reviewed science. Hopefully, the pandemic will correct some bugs in this mechanism, though this is by all accounts a slow and arduous process.

Incidentally, I was chatting with Kushal Mehra about his latest discussion with Shrikant Talageri and Kushal pointed out that he thinks the 1500 BCE dating of Rgveda is also one such Prior which has had an outsized impact on the journey of the Aryan Debate. Prima facie I found this point fair – thought I must say, the 1500BCE date has held up quite well over the centuries (especially since the recent genetic results). But has the date 1500 BCE anchored the research around it, making 1500 BCE appear the best fit for composition of Rgveda and the beginning of consolidation of the Arya into the Indian palimpsest ?

Post script:

I know this place has had a lot of AIT/OIT pieces including this one by me and lot of readers might be fed up by it (even I am to an extent). This isn’t aimed at AIT/OIT but is merely a passing reference to it.

I don’t know how Max Mueller and others came up with the date myself – but it would be an interesting story to research notwithstanding the current research. I would also highly recommend Razib’s podcast with Mallory which delves into the history of the larger indo european question.


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30 thoughts on “Guess values, Priors and Science”

  1. Gaurav, just one question for you: Can you in 1-2 sentences define the Aryan Invasion (Migration) Theory?

    1. The one I subscribe to is – That Vedic culture developed in situ from recent migrants from the Central Asian Steppe who spoke Indo European (old Indic) languages. These migrants shared millennia old ties/culture with other speakers of Indo-European languages (Slavic, Germanic and esp Iranic). And that the ancestors of these migrants – coalesced into a coherent culture somewhere in the Pontic caspian steppe around 2500-3500 BCE. Urheimat doesnt necessarily need to be Pontic steppe.

      1. \These migrants shared millennia old ties/culture with other speakers of Indo-European languages\
        I think the word ‘share’ is not felicitous here. Verb ‘share’ implies some voluntariness and awareness of sharing. e.g. the US and UK share a common language. or Pakistan and India share mountain ranges.
        The word ‘ties’ is wrong- Ties implies some kind of mutual ‘intercourse’ .
        Cognitively both tie and share are wrong here
        Neither is proven/possible in the case of Vedic speakers with gatha speakers or Baltic/Germanic speakers. Vedic speakers show no awareness of non-Indian people or places or languages

        By using wrong words unwittingly, we slide into positions and preconceptions

        1. U r being pedantic here.
          I meant ties/culture.
          Ties is case of two known branches of Arya – Indic and Iranic. Culture for rest.

      2. @Gaurav, to clarify, in a chronological manner, please confirm below. Not asking for proof, still clarifying definition in simple language, with critical elaborations. Please indulge me and confirm 1 to 3, and not just 4.

        1. Somewhere in the Pontic Caspian Steppes in the period 3500-2500 BCE, a “coherent culture” existed.
        Q: Presumably “coherent” means same language, which was an IE language (Old Indic, or PIE itself?). Any other cultural traits of relevance?

        2. The descendants of this “coherent culture,” now speak “Old Indic.” They still live in the Pontic Caspian Steppes, but shared ties with Iranian people especially, but also Slavic, Germanic people.
        Q: Presumably “shared ties” means common language family of IE, or is there anything else relevant? Slavic = eastern European, Germanic = norther/western Europeans, Iranian = present day Iran, or Turan or both?

        3. Some of these descendants of Pontic Caspian Steppes’ “coherent in culture” invaded (the “I” from AIT) to present day India/Pakistan. The movement thus had to be generally from north of the Caspian, west towards Kazakhstan, south towards Turan, south through Afghanistan, and south east to the final destination of present day Pakistan / India. “Invasion” in this case means forceful takeover of land, and a necessary massacre of domestic people.
        Then they composed the RgVeda in India/Pakistan and this became the Vedic Culture. An imposition of their language thus is necessary part of this invasion.
        Q: Timeline for the invasion is 1500 BCE? Was the migration on foot or on horse (presumably a large horde of horses)?

        4. The Aryan Invasion Theory thus means that descendants of a Proto-Indo-European language (the “A” of AIT), who lived in Pontic Caspian Steppes, although the homeland of their ancestors who spoke PIE is unknown (Urheimat unknown), migrated to Pakistan/India in 1500 BCE (?) and composed the RgVeda after migration in Old Indic. Hence, they brought a new language into this region for the first time from the IE family, which became Sanskrit, various Prakrit, and the present day IE languages in India / Pak. The history of IE in India / Pakistan / Bangladesh and Sri Lanka is thus post 1500 BCE.

        PS – I’ll probably stop after your next response, so hopefully it clarifies.

        1. 1. Not PIE – bcoz that doesn’t account for Anatolian branch – but the last major common language.
          Some sort of religious cultural package – guest-host relations, Sacrifices including Horse, Patriarchy, Potentially 3 classes.

          2. Ties in case of Indic and Iranic/Mitanni. Maybe some ties with eastern IE – slavic. Culture with the rest.
          Iranic – Iran + Turan plus lot more regions of Central Asia – up to Mongolia I presume.

          3. Word Invasion is misleading. These were primitive tribal people who did not think up invasions as Alexander/or Kajuda Kadpises did. So migration with some conflict/collaboration makes sense. You can search Razibs piece on Aryan integration theory.
          Presumably with horse drawn carts and chariots and on foot.

          4. Not pontic steppe – Arya is self designation applicable to only Indo-Iranians and not all INdo europeans and is pegged to Sintashta culture in South Ukraine -North Kazakstan.

          1. Thanks for the response. If you’re ever in my neck of the woods, I’ll show you some good steak spots.

  2. Thanks for alerting me to the Kushal-Talageri podcast, Gaurav! Didn’t know that was happening….

    Another good example of history prior is the work of James Prinsep and William Jones. In trying to figure out a sheet anchor for joining Greek and Indian history. So far the dates of Buddha, Alexander’s campaign and Ashoka’s reign – they have held good – archaeologically.

    1. The dates of Alexander’s campaign and Ashoka’s reign have held up well. The date of the Buddha is a much thornier issue – recent Buddhist scholars have been trying to push the date of his death to after 400 BC (when the true date is probably around 486 BC).

      Frankly, the dating of of pre-Mauryan elements in India with the exception of the IVC is somewhat murky. Right wingers will push dates back to fantastical times several thousand years ago based on astronomical arguments or internal literary evidence. At the same time, many western and Indian leftist scholars will assume a rather late date for various cultural developments, then point to archeology as evidence for this comparatively late date. The issue is that much of the dating of archeological evidence is circularly dependent on their dating of various cultural developments. To the extent that carbon dating is actually done, it consistently shows that the archeological developments occurred a few centuries earlier than would be assumed based on the standard scholarly timeline.

      1. @Ummon

        ….the dates of Alexander’s campaign and Ashoka’s reign…

        Hmm, actually not. We only know that Ashoka’s reign succeeded the Buddha’s death by a certain number of years. Only that data point is known.

        Alexander is not recorded by Indian history, epigraphy or archaeology. Even the name – Sikandar – is the Iranian pronunciation which was popularized by the Persian dynasties after the 10th century.

        William Jones made a connection between Sandracottus and Chandragupta Maurya to make the linking pin. But at that time, he did not know that there was another Chandragupta (Guptas) and Samudragupta almost 700 years later in Indian history.

        For me personally, I have always wondered why the ancient Greek historians – Pyrrho, Strabo, Arrian, Megasthenes, Plutarch – did not mention Buddhism at all in their works?

        They talk about “gymnosophists” – naked wise men. Clearly it is the Jains, not Buddhists. It is somewhat possible that Buddhism was already dead or not popular when Alexander visited India.

        1. So the dating of Ashoka is a rather clear milestone in Indian historiography, and the only assumption that needs to be made to do it is to identify Priyadarshi (the author of all the rock and main pillar edicts) as Ashoka. The Dipavamsa refers to Ashoka as Priyadarshi, so this is a reasonable identification. Even if they were two different people, Ashoka would have ruled just after Priyadarshi.

          The list of Greek rulers’ names in the major rock edicts created during Priyadarshi’s reign (Antiochus, Ptolemy, Antigonus, Magas, and Alexander) provides a clear date for when he had to have ruled, since

          Independently of this, if we assume the Buddhist dotted record is valid and Buddha died in 486 BC, and the Mahavamsa and Dipavamsa are correct, and Ashoka became emperor 218 years later, the chronology works out with Ashoka becoming ruler in 268 BC, comporting well with the timing of Priyadarshi’s edicts.

          Alexander’s invasion is of course well secured in the timeline based on the records of Greek sources, and we don’t need Indian sources to know the timing of events in his life.

          As to the lack of Greek observations of Buddhism, that is to be expected. Buddhism was not dominant in the region until after Ashoka’s conversion, and Megasthenes’ observations obviously predate Ashoka. (the Greek historians you mentioned were really all just adapting Megasthenes’ writings).

          The much later Greek writer, Clement of Alexandria, clearly mentions Buddhists in India in his Stromata, though.

          As to the Guptas, the general time of their reign is clearly in the 4th century AD onwards (not the time of Alexander’s invasion), given the start of the Gupta Era as well as the close parallels of Gupta culture with Sassanid culture as well as the fact that they dealt with Hun invaders.

          1. @Ummon

            I am not denying the viability of Alexander’s timeline or the calculation of the gap between the Buddha and Ashoka.

            The intersection of two parallel worlds – Chandragupta Maurya and Alexander – was decided by William Jones with the help of a prior (Sandracottus).

            The rock edicts and pillars of Ashoka cannot be dated with precision – they are stone.

            By the way, Buddha’s birth is consistently sliding to an earlier and earlier date. The latest scientific dating of the shrine at Lumbini is now 550 BC.


            @Saurav and @Ummon- Please read this paper. You will see what I mean. Because this also means Ashoka’s coronation should have been earlier. In fact this means Ashoka was ruling at the time of Alexander’s invasion – makes no sense at all!!

          2. I think you are making a circular argument in the third paragraph. There is no Buddhist record about the exact time of Buddha’s death, but they talk about Ashoka and mention the gap between Buddha’s death and his coronation.The time of of Buddha’s death is calculated by assuming that Devanampiya Piyadasi, the author of major rock and pillar edicts whose coronation can be accurately dated, is same as Ashoka. So Buddhist records do not provide an independent confirmation.

          3. @Ugra

            Did you not read what I said? The pillar can be dated by the names of Greek kings mentioned in it. And I’m well aware of the carbon dating of the tree shrine at Lumbini. The range of dates there is compatible with the dating of Buddha I’ve mentioned, but more importantly, there is no reason to believe a structure didn’t already exist around the tree there before Buddha’s birth.

            @Ace of Spades

            Nope, there is an independent dating for Buddha’s death from the dotted record, which showed 975 dots in 489 AD, resulting in Buddha’s death having been around 486 BC.

          4. The dotted record is not a real physical record. The source is a 6th century Chinese story about a record where people added a dot every year since Buddha’s death. It became famous only because the time of Buddha’s death calculated from this story (486 BCE) is very close to to what you get from the Long Chronology (483 BCE). But it does not mean much once you consider the fact that there are dozens of such stories, most of them placing Buddha within a century of 500 BCE. People who support the Short Chronology also have many such legends to back up their theory.

      2. Isnt there a tooth of Buddha or something in Sri Lanka from where carbon dating of Buddha’s age can be done.

        1. There are so many teeth and other body parts of Buddha scattered across many temples in Buddhist countries that one could construct 100 dead bodies from them.

  3. date of birth of shankaracharya?? i have seen that temples in joshi mutt (north) and govardhan mutt ( puri, east) say that they were established by shankaracharya almost 2500 years ago. kanchi mutt also claims origins before 2500 years. only sringeri mutt in south sticks to his birth in 8th century.
    one of the modern day astrologers (Dr.Pandith) sticks to the 500BC era of his birth based on his birthchart.
    by the time of 7th century buddhism was in decline, but shankaracharya’s teacher kumarila bhatta was taught by a Buddhist.
    other question, if christianity existed in kerala from 1 a d as claimed by the kerala christians, are there any cross references in shankara’s works and christian literature?

  4. @GauravL
    Are you not aware of the following facts:

    1. India’s Iron age started in 16th century BC. How can the date of Rig Veda’s composition be 16th century BC?
    2. Genetics — which you believe is true as if genes speak — shows that migration happened from India to Central Asia; and not the opposite way.

    Or do you willfully neglect them as you believe in something; and it has to be true?

    1. I assume u have been commenting on this blog for atleast an year – especially in light of that your comments are exceedingly ignorant.

    2. Sure, do tell which part is wrong? I hope you clear my ignorance. There is no “Central Asia” that is involved you know if you believe AIT. Did you bother to read Narsimhan? He tells migration from Europe bypassed “Central Asia”.

      1. It mentions BMAC inhabitants did not mate with incoming Indo Aryans but that’s modern day Tajikistan, Afghanistan. Also it doesn’t imply Bypass merely about genetic contribution. Last time I checked Krgystan, Kazakstan is Central Asia too.

      2. You are right that North Central Asia was involved. But that was just for crossing. Around ~2100 BC or so, steppe pastoralists came and then used IAMC to arrive in India. There was no time for settlement or cultural exchange. They more or less moved laterally. This again shows that they bypassed Central Asia, i.e., no Central Asian route was taken. Therefore, no possibility of “culture” being formed in situ or whatever. The arrival date itself is ~2100 BC.

      3. Steppe Pastoralists after mixing with Central Asians did not come. It was Steppe pastoralists that came directly. They did not cross Central Asia; they used IAMC and “bypassed Central Asia”. This is where your misunderstanding lies.

  5. What Narasimhan states with regards to India:
    1. Steppe people came directly by using IAMC route.
    2. No Central Asian/their mixture with Steppe pastoralists came.

    It is obvious Central Asia was not involved at all.

  6. This post is about priors but the reference to AIT/OIT/Rgveda has pushed it past the “event horizon” into one of the classic black hole debates at Brown Pundits. I will try and list out all the priors in the AIT camp.

    1. Steppes people spoke IE languages (or PIE) in the Bronze Age – this is the great-grandfather of all priors. No empirical evidence exists – script evidence or surviving textual tradition. This prior is so good 🙂 that people forget to ask for evidence.

    2. Long before the archaeological ruins of Harappa/IVC were discovered in the 1920s, British and German Indologists fully wrote down the narrative of AIT. Max Mueller (Rgveda@1500 BC!!) died in 1900 – he did not even know that massive Bronze Age cities would be found on the banks of the Sapta Sindhu rivers. This was the beginning of a classic “grandfather prior – father prior”.

    3. The next prior was invented by other Indologists in order to keep AIT a legitimate narrative – that the IVC people must have been non-Aryan.

    4. The Narasimhan interpretation was the long-awaited grandson to that family of priors. By noting the lack of a intrusive genetic component in the Rakhigarhi IVC cline (stable for at least 5000 years), he interpreted that the IE languages could only have arrived in India via the Steppes component after the Mature Harappan.

    This is what happens when four priors are stacked on top of each other – they reinforce each other and seem to be solid.

    FWIW, OIT camp also has a few priors – but I will leave it to the Dasas to articulate them.

  7. Mueller simply back dated 2C for each Veda from the Buddha Ji who he put at 2C b4 Alexander.

    He also thought the world was 5/6000 years old or w/e the Christian belief is/was.`

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