Bava Basra 110a ~ Uncles and Nephews

בבא בתרא קי, א

אמר רבא הנושא אשה צריך שיבדוק באחיה ... תנא רוב בנים דומין לאחי האם

Ravah said: If a man wants to marry a women he should examine the character of her brothers...It was taught in a Baraita: Most sons resemble their maternal uncles.

In today's page of Talmud we continue a discussion of the rights of inheritance, which evolves into a discussion of the influence that ancestors have over their descendents.  The Baraita (a collection of teachings from the era of the Mishnah)  cited in support of Ravah's advice notes that not all sons resemble their maternal uncles, but most do.

Shared Genetic Material

The amount of material we share with our relatives varies by the relationship.  Only identical twins share all of their genetic material.  We share 50% of our genes with each of our parents, and 50% with each of our siblings.  But as you can see below, we share only 25% of our genetic material with our uncles or aunts - the same amount we share with our grandparents.

Image from here.

The amount of genetic material we share with our uncles or aunts does not vary with whether they are on our maternal or paternal side. A boy will no more genetically resemble his maternal uncle than they will his paternal uncle.  And for girls, the rule is the same regarding their aunts.

We find this statement repeated in the Jerusalem Talmud, where it appears as part of a lengthy list originally stated by Abba Shaul:

תלמוד ירושלמי קידושין פרק ד

אבא אוריין איש צדיין אומר משום אבא שאול כו'. רוב חמרים רשעים. רוב גמלין כשירין. רוב ספנים חסידים. רוב ממזירין פקחין. רוב עבדים נאים. רוב בני אבות בויישנים. רוב בנים דומין לאחי האם כשר שברופאים לגיהנם. הכשר שבטבחין שותף עמלק

Most donkey drivers are evildoers, most camel drivers are upright, most sailors are pious, most Mamzerim are cunning, most slaves are haughty, most people of fine genealogy are embarrassed [to take from the public charity fund], most sons are like their uncles [i.e. their mother's brothers], the best doctors go to hell; the best butcher is a partner of Amalek... 

When understood in this context, the connection between uncles and nephews is nothing more than a pithy generalization, and about as likely to be correct as the others on the list.  Like all talmudic aphorisms, it was uttered in a different time and place from our own. If you really want to know who your child will resemble, you should look no further than you and your spouse.  That will be the most likely predictor of your child's character, whether genetically encoded or socially constructed.  

Yoma 20b ~ From The Talmudology Yom Kippur Archives: Sound Propagation at Night

Tomorrow evening (or in a few hours if you are in Australia) we observe Yom Kippur, the Day of Atonement. So we will reach into the Talmudology archives to a post that discussed the propagation of sound at night.

In discussing the service on Yom Kippur, the holiest day of the Jewish Year, the Talmud notes that the voice of the Cohen Gadol, the High Priest, could be heard from a distance of ten parsangs. In case you were wondering, a parsang is an old Persian measure, and is about 3 miles or almost 5km. This means that the voice of the High Priest could be heard over 30 miles away! The Talmud notes that it could be heard at this distance even during the day, when sound does not travel as far as it does at night. Here it is, in the original:

שקלים כ,א

דְּאָמַר מָר: וּכְבָר אָמַר ״אָנָא הַשֵּׁם״ וְנִשְׁמַע קוֹלוֹ בִּירִיחוֹ. וְאָמַר רַבָּה בַּר בַּר חָנָה אָמַר רַבִּי יוֹחָנָן: מִירוּשָׁלַיִם לִירִיחוֹ עֲשַׂר פַּרְסֵי

וְאַף עַל גַּב דְּהָכָא אִיכָּא חוּלְשָׁא, וְהָכָא לֵיכָּא חוּלְשָׁא. וְהָכָא יְמָמָא, וְהָתָם לֵילְיָא

דְּאָמַר רַבִּי לֵוִי: מִפְּנֵי מָה אֵין קוֹלוֹ שֶׁל אָדָם נִשְׁמָע בַּיּוֹם כְּדֶרֶךְ שֶׁנִּשְׁמָע בַּלַּיְלָה? מִפְּנֵי גַּלְגַּל חַמָּה שֶׁמְּנַסֵּר בָּרָקִיעַ כְּחָרָשׁ הַמְנַסֵּר בַּאֲרָזִים

There already was an incident where the High Priest recited, in his confession that accompanied the placing of hands on his bull on Yom Kippur: Please God, and his voice was heard in Jericho. And Rabba bar bar Chana said that Rabbi Yochanan said: The distance from Jerusalem to Jericho is ten parasangs.

…here it was during the day, when sound does not travel as well, that the High Priest recited his confession… As Rabbi Levi said: Why is a person’s voice not heard during the day in the manner that it is during the night? It is due to the fact that the sound of the sphere of the sun traversing the sky generates noise like the noise generated by a carpenter sawing cedars, and that noise drowns out other sounds…

As we approach Yom Kippur, we might ask if this is true? Does sound really travel further at night? And if so, why?

Yes. It is true

Rabbi Levi is correct. Sound does indeed travel further at night, as you can see below in this helpful graphic. (For the man with the trumpet, think Cohen Gadol. For the dog, think Jericho.)

From here.

The first thing to know is that the speed of sound is dependent on the temperature of the air. Sound moves quicker in warm air and slower in cold air. During the day the sun heats up the earth’s surface, and in particular it heats up the air that is closest to the ground, which is where the sound travels the fastest. But a heat gradient bends the sound waves upwards, much in the same way that a lens bends light rays. (The gradient in which atmospheric temperature decreases with elevation by an amount known as the adiabatic lapse rate.) As a result, the sound waves travels up and away from the listener, and the sounds are quieter.

The reverse happens at night. At night the ground cools quickly. The higher air is warmer than the air close to the ground. The sound further from the ground travels faster at night causing the sound wave to refract back towards the earth. The listener now hears them as louder than they were during the day. It’s physics! (Though it should be noted that some physicists dispute this explanation.)

It’s not just sound waves

Why radio waves travel further at night. From here.

Here’s a fact that Rabbi Levi did not know. It’s not just sound that is heard better at night. Radio waves are heard better at night too, though for an entirely different reason. To be precise, this does not happen with all radio waves, but just those on the AM and short wave frequencies. Because radio waves only travel in straight lines, they do not follow the curvature of the earth’s surface, and so have a natural range of only 30-40 miles. But they can be transmitted up to the ionosphere, where they bounce off of it and down, back to earth. At night, that ionosphere is protected from the electromagnetic radiation that streams from the sun and tends to distort it. And so the radio waves are reflected back down with less interference, which means they travel further and are easier to detect. As a result, some distant AM radio stations (remember those?) can only be heard at night, though the whole thing becomes rather a moot point since nearly everything broadcast can now be found on the internet, for which the ionosphere is not needed.

Noise pollution

We have demonstrated that sound travels further at night, using our knowledge of the properties of sound waves and the phenomenon of refraction. Rabbi Levi knew none of this, but he had something that very few of us today have: a quiet natural environment. What many of us never experience thanks to noise pollution, he experienced each and every night. He, together with the other sages of the Talmud lived in a world that had no noise other than the sound of human voices around a crackling fire and the background music of the natural world. It was an utterly different experience. Our modern world has given us many things to be grateful for, but noise is not one of them.

May you be blessed for a quiet and peaceful year ahead.

גמר טוב

{Want more Talmudology about Yom Kippur? Click here and here.]

Bava Basra 97b ~ Wine and Snake Venom

In today’s page of Talmud there is brief reference to uncovered wine that is left overnight.  This wine should not be drunk because "סכנה היא" – it is dangerous to do so. Shmuel ben Meir, known as the Rashbam (d. ~1158) outlines the cause of this danger: ואיכא למיחש שמא שתה הימנו נחש - "we should be concerned that a snake may have drank from the wine."  The Rashbam, usually known for his lengthy commentaries, left out the most important part of the explanation. While drinking from the water, perhaps the snake expelled some of its venom into the wine, which would then become dangerous to drink.

Don't touch that wine

The rabbis of the Talmud were very worried indeed about the health effects of water - and wine - that had been left uncovered.  This concern was codified by Maimonides, and later by Ya'akov ben Asher (d. 1340) in his famous halakhic work called the Arba'ah Turim. 

טור יורה דעה הלכות מאכלי עובדי כוכבים סימן קטז 

דברים האסורים משום סכנה
  יש דברים שאסרום חכמים משום סכנה כגון משקין שנתגלו שיש לחוש שמא שתה מהן נחש והטיל בהן ארס אפי' אם שתו מהן אחרים ולא הוזקו אין לשתות מהן  שיש נחש שהארס צף למעלה ויש שארס שלו מפעפע עד אמצעית המשקה  ויש שהארס שלו שוקע לשולי הכלי לפיכך אפי' שתו ממנו אחרים ולא הוזקו אין לשתות מהן דשמא ארס של הנחש ששתה מהן שוקע ואלו המשקין שיש בהן משום גילוי מים יין חלב ודבש ושום כתוש 

Tur, Yoreh De'ah 116. Things that are Prohibited Because they are Dangerous

There are things that the rabbis of the Talmud prohibited because they are dangerous. For example, liquids that were left uncovered, because of the possibility that a snake drank from the water and expelled some of its poison into them. Even if others had drunk from the liquid, and not been injured, one should not drink from them.  For some snake venom floats on the surface, and some sinks to the middle and some moves to the edges of the vessel. Therefore, even if others had drunk and had suffered no harm, one should not drink from them, for perhaps the venom from the snake that had drunk the water had sunk to the bottom. The following liquids should not be drunk if they were left overnight in an uncovered vessel: water, wine, milk, honey, and crushed garlic...

The normative Code of Jewish Law, the שולחן ערוך agreed, but added an important caveat:

שולחן ערוך יורה דעה הלכות מאכלי עובדי כוכבים סימן קטז סעיף א 

משקים שנתגלו, אסרום חכמים דחיישינן שמא שתה נחש מהם והטיל בהם ארס. ועכשיו שאין נחשים מצויים בינינו, מותר

The rabbis forbade drinking from liquids that were left uncovered,. They were concerned that a snake may have drunk from them and expelled some of its poison into them. But now that snakes are not commonly encountered, this is permitted. (Shulchan Aruch Yoreh De'ah 116:1)

So today it is permitted for us to drink from an uncovered pot, but only in a place that does not have a problem with poisonous snakes.  Which is not helpful. There are poisonous snakes in nearly every state in the US, resulting in about 2,000 human envenomations each year, and we have noted before that Israel has its own problem with snakes, including the Palestinian Viper.  The World Health Organization estimates that snakes kill between 20,000 and 94,000 people per year. So exactly where this leniency of the Shulchan Aruch might apply is not clear.

But is drinking snake venom indeed dangerous? Maybe not. In 2012 India Today reported that police in New Delhi had seized about half a liter of snake venom to be used "in high-end raves planned for Valentine's Day in and around the national capital." Apparently the venom, when ingested, produces a euphoric state. Who knew?

VIDEO EVIDENCE - DRINKING COBRA VENOM

It is really hard to find any peer-reviewed scientific studies about people drinking snake venom, because, um, it's a silly thing to do.  But that doesn't mean it hasn't been done. So where could we turn to find people doing silly things? YouTube of course.(The real action begins at 10:13).

Want more? Ok then. Here's another one. This time it involves drinking the venom directly from spitting snake. Apparently, these kind of human interest stories are popular in India. 

WHY IT IS SAFE TO DRINK SNAKE VENOM

If you are a diabetic and take insulin, or know someone who does, you may have wondered why the drug has to be injected. It would, after all, be much less bothersome to swallow an insulin pill than to inject insulin several times a day.  The reason is that insulin is a protein, and like all proteins, it is easily broken down by heat and, more importantly, by the acid environment in the stomach.  Our gastrointestinal tracts evolved to break down proteins into their building blocks - and they perform a wonderful job doing precisely that.

Like insulin, snake venom is a complex protein. And so, like insulin, it too is easily broken down in the very acidic environment of your stomach.  Of course, if intact venom gets into your bloodstream, it could kill you. But if you drink venom, then the intact protein never does get into your bloodstream. You don't need to be an Indian snake charmer to safely drink snake venom. You just need a working digestive system.

How snakes drink

In case you were wondering how we know how snakes drink, here is a diagrammatic view of the apparatus used to record the kinematics and water transport during drinking. The video camera was placed to the left. LED, light-emitting diode. From Cundall, D. Drinking in snakes: kinematic cycling and water transport. The Journal of Experimental Biology. 2000; 203, 2171–2185.

The Talmud was concerned that snakes leave venom in the water from which they drank, and that a person drinking from that water would then suffer from envenomation. As we have seen, this concern has no biological basis, although theoretically, if there was an open cut or ulcer in the mouth, ingested venom could get into the bloodstream and then cause its havoc.  But there is another reason why the talmudic concern is overstated.  Snakes, you see, don't leave any venom when they drink water.  As you may have noted from watching the first video, it takes a lot to get a snake to expel its venom - like sticking a blue pen in its mouth.  Venom is a snake's most precious commodity, and it has evolved to protect that commodity. Snakes only release venom when they are in danger, or ready to strike their prey, and not otherwise. Want a great example? The venomous rattlesnake. That species has evolved a warning rattle to tell would-be predators that if they get any closer, they will be bitten. This only makes evolutionary sense if it was in the snake's best interest to do everything possible to conserve its venom.

In a fascinating article on how snakes drink published in The Journal of Experimental Biology, David Cundall notes that a snake's tongue does not carry or move water, and that "in many snakes, the tongue does not visibly move during drinking." That leads to the conclusion that snakes are suction drinkers. And that makes them even less likely to leave any venom behind in the water.

So let's put this all together:

1. Snakes don't release their venom unless they are threatened or hunting. 

2. Snakes use suction when they drink water. Their mouths are not open, which is needed when they are expelling venom.

3. Snake venom is not dangerous when drunk.

4. (If somehow venom did get into the water, it would be greatly diluted.)

So there is no danger if you were to drink from wine from which a venomous snake had drunk. None. But this was not known to the rabbis of the Talmud, for whom the advice to stay away from all things snake made for a very good public health message.

[Repost in part from Bava Kamma 115.]

Bava Basra 95 ~ The Smallest Ramanujan Taxicab Number

This post is for tomorrow’s page of Talmud to be studied, which is page 1,729 of the Babylonian Talmud. Print it up now and enjoy, and Shabbat Shalom from Talmudology.

The number of tomorrow’s daf, (Bava Basra) 95, has some special mathematical properties. For example, it is a Thabit number, (also called a 3-2-1 number) which is an integer that is of the form 3 · 2ⁿ - 1. But there is another mathematical curiosity about tomorrow’s page number. Starting from the beginning, it is page number 1,729 of the Babylonian Talmud. And 1,729 is the smallest Ramanujan Taxicab Number, a number that can be written as the sum of two cubes: (1³ + 12³=1729.) In two different ways: (9³ + 10³=1729).*

[*These numbers are also known as Hardy-Ramanujan numbers. Also, to be precise, they are numbers that can be can be written as the sum of two cubes using positive integers. Let’s keep going.]

Here is one version of the story of how these numbers were discovered:

Curious properties sometimes lurk within seemingly undistinguished numbers. 1729 sparked one of maths most famous anecdotes: a young Indian, Srinivasa Ramanujan, lay dying of TB in a London hospital. G.H. Hardy, the leading mathematician in England, visited him there. 'I came over in cab number 1729,' Hardy told Ramanujan. 'That seems a rather dull number to me.'

'Oh, no!' Ramanujan exclaimed. '1729 is the smallest number you can write as the sum of two cubes, in two different ways.' Most of us would use a computer to figure out that 1³ + 12³ = 9³ + 10³ = 1729. Ramanujan did it from his sickbed without blinking.

Mathematicians have mined his theorems ever since. ..Far more than just another number theory, 1729 is the first of the 'Ramanujan numbers' or taxicab numbers. Mathematicians are competing to search for more of them (with higher powers) and testing the strength of new computing technology. The search is seen as mathematics' current greatest challenge. Only recently, a lost bundle of Ramanujan's notebooks turned up in a Cambridge library setting maths off on a new voyage of discovery.

“Ramanujan, a largely self-taught mathematician, seemed to solve problems instinctively and said his formulas came to him in the form of visions from a Hindu goddess. During the height of British colonialism, he left his native India to become a protégé of mathematician G.H. Hardy at Cambridge University in England.”

— Emory University News Center, October 22, 2015.

In case you are wondering, this is the only page of the Talmud that is a taxi-cab number. (There is a machloket achronim [debate] as to whether 2 is a taxicab number. Some lists include it. Others don’t. Personally, I don’t think it counts, but my opinion on the matter is of zero mathematical importance.) The next one is 87,539,319.