Category: Domestication

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Reindeer domestication

From our occasional contributor Michael Kubisch.

Reindeer have been domesticated by denizens of the Northern hemisphere for some time – but exactly for how long and  whether domestication occurred at different sites or only once has been the matter of some debate. Estimates of how long ago domestication might have happened have ranged from as long as 20,000 years ago to as little as 3000. Part of the problems stems from the lack of archaeological records that could pinpoint  a more exact time frame. The evidence for the shorter period relies mostly on ethnographic observation, such as the development of certain implements (for example saddles) that early reindeer herders developed apparently after contact with other people of the central Asian steppes.

But did domestication  happen more than once? A recent paper by a group of researchers from Oslo sheds some light on this question.  After analysis of a number of DNA markers they conclude that the Sami people of Northern Scandinavia domesticated reindeer independently from indigenous people in what is now Russia.  Moreover the evidence points to the existence of three distinct gene pools suggesting that domestication even within Russia may have occurred more than once.

And there  is another interesting observation: comparisons with gene markers from wild reindeer suggests that introgression of “wild” genes into domestic reindeer appears to have happened quite frequently through the ages,  but that only some of the  wild populations have made genetic contributions suggesting perhaps different propensities for domestication among animals of various wild herds.

Unfortunately there is increasing concern about the future of reindeer agriculture. The Sami herders, who live in Scandinavia, Finland and parts of Russia, are beginning to feel the effects of global climate changes. The rapid warming trend that seems to occur in the Northern hemisphere interferes not only with foraging but also with the ability to move animals across what used to be solid ice. And many Sami now fear not only the loss of their livelihood, but also the disappearance of a substantial part of the culture, which has always been intricately linked to reindeer.  

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Was sunflower domesticated in Mexico or what?

I don’t know much about sunflower. That’s obvious enough from the cavalier fashion in which a recent Nibble of mine referred to a press release on a PNAS paper on sunflower domestication by David Lentz and others. ((David L. Lentz, Mary DeLand Pohl, José Luis Alvarado, Somayeh Tarighat and Robert Bye. Sunflower (Helianthus annuus L.) as a pre-Columbian domesticate in Mexico. Proceedings of the National Academy of Sciences 105: 6232-6237; published online as 10.1073/pnas.0711760105. The paper is behind a paywall but the supplementary material is available and gives a taste. Some nice pix.)) Briefly, that paper presented a range of archaeological, linguistic, ethnographic and ethnohistoric evidence for the domestication of sunflower in Mexico by 2600 BC. This would complement a separate, independent, well-attested domestication in the Mississippi Valley. That’s important not only academically but also for the insights it would give into genetic structure within the species, and hence possible breeding strategies.

But it looks like I unwittingly walked into a bit of a controversy. It seems things are a bit more complex than the press release made out. In a 2007 short communication in GRACE, the great Charles Heiser reverses himself with regards to some archaeobotanical material he had previously identified as a sunflower achene and as a result comes out against the Mexican domestication for the crop first advocated by Lentz in 2001. The available molecular evidence seems to support Heiser.

I don’t know much about sunflower. But after today, I know a little bit more. And I’ll be keeping an eye on this academic spat to learn more.

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Cassava diversity 101

After hanging out with experts for three days here in Cali, this is what I think I know about cassava genetic diversity:

  • There’s a hotspot in Brazil, but Central America is pretty diverse too. Those two places are also where the wild species are most numerous. There is geneflow between wild and cultivated populations.
  • There’s little geographic structure within the New World diversity, except for Guatemalan material being way genetically distinct (and higher in protein to boot). Lots of geneflow, I guess.
  • The African material is less diverse than the American, but not much, and significantly distinct from it. Selection, and isolation.
  • Within Africa, the Nigerian material is somewhat distinct. In general, there is more geographic structure in Africa than in the Americas.
  • Asia received material historically from both Brazil (via Africa) and Mexico (via the Philippines), but there hasn’t been the differentiation there that is seen in Africa. There hasn’t been as much selection of natural hybrids in Asia as in Africa.
  • Weird mutants keep turning up, including “sugary cassava,” “ketchup cassava” (the pinkiness is due to lycopene), and amylose-free clones. 
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Avocado domestication and iconography

I took advantage of the thirteen hour flight to Lima to catch up on some reading, including a recent paper reviewing the state of knowledge on avocado diversity and domestication. ((Mari­a Elena Galindo-Tovar, Nisao Ogata-Aguilar and Amaury M. Arzate-Fernandez (2008) Some aspects of avocado (Persea americana Mill.) diversity and domestication in Mesoamerica. Genetic Resources and Crop Evolution 55:441-450. http://dx.doi.org/10.1007/s10722-007-9250-5.)) The authors postulate that avocado exploitation began in Central Mexico with the gathering of fruits from the forest, possibly as long ago as 8000 BC. Then, when the climate changed for the worse around 4500-2000 BC, people began to tend and cultivate the tree in forest gardens. The final phase was one of intensive cultivation in homegardens and active dispersal around the region and into South America.

That’s all very interesting, but the thing that really stuck with me was the observation that the avocado tree is represented on Hanab-Pahal’s sarcophagus from Palenque. Not on the famous “astronaut” lid, however, but on its side. Ten ancestors are seen around the sides of the sarcophagus, arising from a crack in the earth, each with a fruit tree, forming a sort of homegarden around the dead king. Among them is Lady Olnal, and she has an avocado tree. Unfortunately, I couldn’t find a picture of this on the internet. But the reason it struck me is that I’d just been looking at photos of more recent, and geographically somewhat distant, but no less botanical, funerary art. Even in death, people of all ages and cultures like to be surrounded by plants, it seems.

And, being in Peru, all this rumination about art and agrobiodiversity couldn’t help but remind me of Marcos Zapata’s painting of the Last Supper in Cuzco Cathedral (1753). That famously features roast cuy, but check out the thing to the left of the cuy’s head. Is it a maca? What other crops can you identify? Donwload the full-sized version on the photo and see. No avocados, alas.

cuy.jpg