How the Ju|’hoan Make Poison Arrows

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A modified version of a map in a paper by Caroline S. Chaboo, Megan Biesele, Robert K. Hitchcock, Andrea Weeks

When I was a child, my grandmother taught me how to make arrows from the softwood of a poplar, a tree that was abundant in the woods that we could step into from my backyard. Later in adolescence, biased from the movies that I watched,  I perceived arrows to be “primitive”.

It is another case of truth differing from popular perception.

Human ancestors were hunter-gatherers millions of years ago, but archery appeared relatively late, around 65 000 years ago. To make arrows far more effective hunting weapons, humans have learned to extract poisons from plants, frogs and beetles. Unfortunately, indigenous communities across the planet who hunt with arrows are gradually becoming sedentary and are losing traditional knowledge. They include  some native North American Indians; Paraguay’s Ache; the Pumè in Venezuela; the Hadza in Tanzania and 113 000 people of various San communities (use “click” languages) from Angola to South Africa (see map). Some San groups are the only ones in the world who are known to use beetles to make their poison arrows. Based on their local conditions, these invariably isolated communities have developed their own specialized poison use and preparation.

Authors of a 2016 study, focused on two San groups from Namibia: the Ju|’hoan and Hai||om. The former who live near Nyae Nyae told researchers that, thanks to older hunters, they had learnt to locate plants of the genus Commiphora, which are host to the larvae of two beetle species shown below.

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At margin of the shrub, using either a metal stick or a traditional wooden one, the hunter either digs a new 1 meter ditch encircling the plant or extends that of a preexisting one. ( (1) in picture set below)  The hunter uses his finger to sift the loosened sand with his fingers, straining out the beetles’ oval-shaped cocoons . When enough cocoons have been collected into an ostrich egg shell or plastic container (2), the hunter heads home.  The hunter makes sure that the concave surface of an animal knuckle bone faces upwards in the sand in front of him, and he places the beetle cocoons nearby. A small fire is lit. He breaks open a cocoon and taps out the single larva (3), discarding any pupae and adult insects.  Using a stick as a pestle, he rubs hard against the skin to loosen tissue, then extracts it to mix on the bone mortar (4), using about 10 larvae for every arrow. He chews the bark of Acacia mellifera to produce saliva which is mixed with the larval tissue and their “blood”, hemolymph. A bean of the toxic snake bean plant (Bobgunnia madagascariensis)  is heated over the fire, cooled and added to the mixture. Ju|’hoan informants at|Xai|Xai in Botswana told one of the researchers that they use the juice of Sansevieria plants to improve the poison. Without touching the poisonous mix, the hunter applies the ‘beetle paste’ of D. nigroornata larva with a twig to the dried sinew that fastens the arrowhead to the shaft.  The arrows are then finally dried. Their poison becomes less potent with time and expires within a year.

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The poison is a  protein known as diamphotoxin. As far as proteins go, it is very small and simple structure. It’s a single chain polypeptide with a molecular weight of only 60000 grams per mole. The poison is a so-called ionophore, affecting the permeability of red blood cells. Many small ions, including those of calcium (Ca2+), enter indiscriminately. The wounded animal’s red bloods, about 75% of them, then burst.  This leads to a severe shortage of oxygen throughout the body. The release of ions from ruptured cells also wreaks havoc in kidneys. Convulsions, paralysis, and death ensue. As far as natural poisons go, diamphotoxin is highly potent. Whereas the lethal dose that kills 50% of animals (LD50) for chlorotoxin (scorpions), nicotine, amatoxin (amanita mushrooms) and frogs’ batrachotoxin (from poison dart) is 4.3, 3.3 , ~0.5 and ~0.002 mg/kg, respectively, diamphotoxin’s is only 0.000000025 mg/kg (25 picograms/kg) for mice. That implies that one gram of pure diamphotoxin would be enough to kill (50%)*(1012 pg/g)*(kg/25pg)*(mouse/0.020 kg) = one trillion twenty-gram mice. 

Although the San groups have no molecular explanations for their weapon of choice, in order to develop the method of preparation, they have performed a type of laboratory science, with all its trial and error. And just like with modern science, it took a leap of imagination to think of extracting the poison from an insect’s larvae in the first place. Unfortunately, unlike practitioners of  Western science, the San groups have not left any written records of how and what their previous generations have discovered.

Sources: 

Chaboo and Al. Beetle and plant arrow poisons of the Ju|’hoan and Hai||om San peoples of Namibia. Zookeys Feb 01, 2016 958: 154

Harpe and Al. Diamphotoxin. The arrow poison of the !Kung Bushmen. Journal of Biological Chemistry. October 10, 1983 258, 11924-11931.

Jacobsen and al. Effect of Diamphidia toxin, a bushman arrow poison, on ionic permeability in nucleated cells. Toxicon Volume 28, Issue 4, 1990, Pages 435-444

 

Other LD50 data: https://web.archive.org/web/20150412045434/http://biology.unm.edu/toolson/biotox/representative_LD50_values.pdf

 

Icicle Adventures

Despite below freezing temperatures, ice can melt in sunlight. This indicates that ice molecules can easily get agitated to above freezing temperatures even if surrounding air molecules have less energy of motion. If the melt-water runs down an edge, heat can be taken away again from the dripping water. An icicle begins to form. If water keeps flowing over the bud, the icicle will grow. It not only serves as a continuous source of crystals, dripping water helps take heat away from the growing icicle.

When ice forms, it actually releases heat. What, aside from water, takes heat away so that more flowing water can freeze?   It is the up-draft of air caused by the icicle being  warmer than its surroundings. The heat is taken away more slowly at the top of the icicle, where it grows more slowly. At the base, the opposite is true; growth is faster, hence the carrot shape.

With all that mind and the expectation of seeing the same pattern again, I was of course startled when I saw this yesterday:EQlXZbGWkAIaTCz

By looking around, I soon realised that’s not what the icicle looked like when it formed. A meter to the left of that strange upside down V-formation, I noticed the following.

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In all likelihood, the odd shape originally had three components, a familiar carrot shape but joined to a pair of other icicles that had grown along the edges of the angular frame. Metal is efficient at removing heat, and it probably adds a complicating variable to the shape of the arms clinging to the metal. One of the arms detached itself from the frame upon partially melting and then rotated; the other arm broke off.

I was tweeting these two pictures when I told myself I should be out there instead, observing to verify if guess was right. The same structure to the left now looked like this:

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Seconds after I snapped the photo, the whole structure came crashing on the floor of the deck. It never got a chance to rotate as much as the original icicle.

The best, however, was yet to come. Annie van Leur saw my pictures and remarked the following:

 

 

 

Cute. However, not as interesting as our Michigan ice apples. When freezing rain coats rotting apples and the mushy rotten apple falls out, it leaves a shell of ice.

And she posted this:

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Why are there often ridges on icicles? It’s ionic impurities in the water that play an important role. Graduate student Antony Chen designed a table-top apparatus for the controlled growth of icicles. He experimented with different conditions of temperature, water supply rate, ambient air motion, and water purity. When pure water was used, ripples did not appear on icicles. They looked like the icicle in Figure 1. Even a low salt concentration (0.008%) caused ripples to grow and travel on icicles (Figure 2). In the absence of salt,  dissolved gases or non ionic surfactants had no effect on the growth of ripples. When the air was still, icicles grew more tips (Figure 3). Gently stirring the air caused the shapes to become more monotonous.

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Figure 1
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Figure 2
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Figure 3

 

 

SOURCES:

The Point of Icicles https://uanews.arizona.edu/story/point-icicles

Experiments on the Growth and Form of Icicles https://tspace.library.utoronto.ca/handle/1807/44105

Icicle Photos https://www.physics.utoronto.ca/Icicle_Atlas/rogues_gallery.html

 

 

 

 

 

 

Economics Vs. Environment: A False Dichotomy

mid-globeThe false dichotomy of economics versus environment has long existed because it is unfortunately too easy to sweep health and environmental costs under the rug or to have government consistently pick up the bill for consequences of short-sighted “growth”.

Here’s a letter sent to the Economist by former World Bank, senior vice president, Vinod Thomas, specifically arguing that by addressing climate change we are really safeguarding the economy in the long run.

It is true that climate change is not just an environmental problem; it cuts across all activities. Yet the recipe for economic growth from mainstream economists, including those of the The Economist newspaper, disregards climate change.  Yes economic textbooks cover externalities or spillover effects, but these have not been integral to growth analysis. A search finds abundant climate studies, but less than 0.5% of the numerous growth articles over the past 50 years seem to factor climate effects.

That allows politicians such as Jair Bolsonaro, Brazil’s president, to argue that environmental protection is inimical to growth,even as the emerging reality is the opposite. American policy too, sees any deregulation, including policy that mortgages the environment, as pro growth. Yes environmental destruction may boost short term growth, but the climate outcomes hurt long term growth and welfare.

So changing the conduct of growth economics is essential if we are to avert a climate catastrophe.Unless the economics profession stops ranking and rewarding countries based primarily on how much they deregulate and boost short term GDP, the climate action that you rightly call for will continue to lag dangerously.

Here is another discussion from the journal Nature that is more detailed and broader in scope:

The cost of a warming climate

 

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