Biology

Could our furry friends’ features be the result of stem cell defects?

Silver fox displaying 'domestication syndrome' (Photo credit: luz rovira via Flickr)

Silver fox displaying ‘domestication syndrome’ (Photo credit: luz rovira via Flickr)

In the 1950s, Russian fox fur breeder Dmitri Belyaev embarked on a monumental experiment in the Siberian city of Novosibirsk. He wanted to see if he could domesticate wild foxes by selectively breeding only the tamest in each generation. He was essentially trying to re-run thousands of years of history — dogs and many of our farm animals were domesticated several thousand years ago, and scientists are still debating exactly how this occurred.

The Novosibirsk experiment is noteworthy not only because it revealed that tameness could indeed be bred into a line of wild animals after only a few generations. Nor because the landmark experiment is still running, sixty years on. It is noteworthy because it has demonstrated another aspect of domestication that biologists since Charles Darwin have puzzled over — that domesticated animals aren’t just tame, but they are cute to boot. Many have floppy ears, baby faces and endearing patches of white fur that could well spell death for an animal in the wild. In the Novosibirsk experiment, foxes started looking more like pets over the generations, even though the sole criterion for selection was tameness.

A threesome of academics has now come up with a hypothesis that could explain why selecting for a docile behaviour bring with it the suite of physical characteristics known as ‘domestication syndrome.’ According to the hypothesis, it could all come down to a group of stem cells called neural crest cells. These cells form near the spinal cord and then march across the developing vertebrate embryo to form pigment-producing melanocytes; bone, cartilage and teeth in the skull; and portions of the adrenal gland and brain.

The question that this hypothesis raises is: could small changes to neural crest cell gene expression be at the centre of domestication syndrome’s disparate features? Experimental evidence will need to sort the answer out to that, but it’s an intriguing idea nonetheless.

I wrote a brief article on the paper for Cosmos — check it out here.

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