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clever Charlie Darwin

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A photo taken by me! King Charles seated in state in the Musuem of Natural History, London. It was a thrill to be granted an audience

A photo taken by me! King Charles seated in state in the Musuem of Natural History, London. It was a thrill to be granted an audience

I recently decided to reread Darwin’s Origin of Species, which was really reading it for the first time as my first reading was pretty cursory, and I could barely follow the wealth of particular knowledge he used for cumulative effect to adduce his theory. This time I’ve been doing a closer reading, and becoming increasingly impressed, and I’ve only read the first chapter, ‘Variation under Domestication’.

Darwin’s argument here of course is that domesticated horses, dogs, birds and plants have been artificially selected over long periods of time, and often unconsciously, to suit human needs and tastes. This might seem screamingly obvious today, and to a degree it was recognised in Darwin’s time, but because of an inability to take the long view, and also because of the then-prevalent paradigm of the fixity of species, breeders and nurserymen tended to under-estimate their own cumulative powers, and to claim, for example, that dogs and pigeons had always come in many varieties. Even Darwin was uncertain, and was willing to concede – writing of course before the advent of Mendelian genetics, never mind the revolution wrought by the identification and analysis of DNA as the molecule of inheritance – that in some cases the breeders might be right:

In the case of most of our anciently domesticated animals and plants, I do not think it is possible to come to any definite conclusion, whether they have descended from one or several species.

He was even prepared to concede that it was ‘highly probable that our domestic dogs have descended from several wild species’, while at the same time arguing that the breeding of dogs, in Egypt, other parts of Africa and Australia (where, in his Beagle travels, he observed dingoes, which he may have seen as semi-domesticated by the Aborigines) extended back far further in time than most people suspected. We now know that Darwin’s concession here was ‘premature’. The latest research strongly suggests that our domesticated dogs trace their ancestry to a group of European wolves dating from 19,000 to 32,000 years ago, and probably now extinct. That’s a time-frame Darwin would’ve baulked at, and it’s both funny and kind of tragic that this is something I’ve ‘discovered’ after 30 seconds of selective internet searching. There’s no doubt, though that Darwin’s bold but always informed speculations were heading in the right direction.

Particularly informed –  and bold – were his speculations about pigeons. This is hardly surprising as he spent several years studying and breeding them himself. Interestingly, he started doing so because he’d become convinced that all the fancy pigeons then on show were most likely derived from one common species, the rock pigeon or rock dove (Columba livia), a view already held by some naturalists but few breeders.  He devotes several pages in Chapter 1 to arguing his case, for example pointing out that the ‘several distinct species’ argued for by breeders can be crossed with complete success, that’s to say with no signs of sterility or more than usually defective offspring.

So, as with dogs, I decided to look up what the latest research was on the ancestry of English carriers, short-faced tumblers, runts, fantails, common tumblers, barbs, pouters, trumpeters and laughers, to name some of the pigeons Darwin mentions in the chapter, and was excited to find that a piece of research published as recently as 2013 has confirmed Darwin’s hypothesis. Cheaper and faster genome sequencing technologies have enabled researchers to sequence the genomes of many wild and domesticated birds, and they’ve found that all of the latter are clearly closer to C livia than to any other wild species. It only took just over 150 years for Darwin to be proven correct.

Close reading like this really does reap some fun rewards, and I’ll finish with two more examples. Darwin wrote of how in the world of breeding, quite a drastic change can be brought about in one breeding step, as in the case of the fuller’s teasel with its hooks. He goes on:

So it has probably been with the turnspit dog; and this is known to have been the case with the ancon sheep.

Not knowing wtf he was talking about, I irritatedly decided to look up these unknown creatures. The turnspit dog is a now-extinct breed, bred specifically from around the 16th century to provide the dogpower to turn meat on a spit, the only conceivable way of cooking large joints of meat in your average fancy household for a couple of centuries. The dog, or dogs, because the system worked better if you had two of them engaged in shift work, turned a wheel by running inside it, rat-like, until the meat was cooked. They were known to be long-bodied and short-legged, but details of how they were bred aren’t known, as they were apparently beneath scholarly consideration. They certainly weren’t seen as cuddly pets – if you treat creatures as slaves it heightens your contempt for then (cf Aristotle) – and they were even taken to church as foot-warmers. They’d disappeared entirely by the end of the 19th century.

It's a dog's life?

It’s a dog’s life?

The ancon sheep was a short-legged type, apparently bred from a single individual in the USA in the late nineteenth century, its short legs having the singular advantage, to some, of curtailing its hopes of freedom by jumping the fence. The term ‘ancon’ has since been used by breeding researchers to describe strains of creatures arising from an individual with the same phenotype.

Achondroplastic_sheep

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Written by stewart henderson

June 4, 2016 at 11:00 am

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