Tuesday, March 5, 2013

A follow-up on dogs and animal domestication

Earlier today I published an article about how dogs regard humans as their assistants, perhaps even as tools to be used to help solve a problem.  In a comment to that article, reader Chris pointed us to a National Geographic article about animal domestication that I found very interesting.  Here's an excerpt.

Led by a biologist named Dmitry Belyaev, researchers at the nearby Institute of Cytology and Genetics gathered up 130 foxes from fur farms. They then began breeding them with the goal of re-creating the evolution of wolves into dogs, a transformation that began more than 15,000 years ago.

With each generation of fox kits, Belyaev and his colleagues tested their reactions to human contact, selecting those most approachable to breed for the next generation. By the mid-1960s the experiment was working beyond what he could've imagined. They were producing foxes like Mavrik, not just unafraid of humans but actively seeking to bond with them. His team even repeated the experiment in two other species, mink and rats. "One huge thing that Belyaev showed was the timescale," says Gordon Lark, a University of Utah biologist who studies dog genetics. "If you told me the animal would now come sniff you at the front of the cage, I would say it's what I expect. But that they would become that friendly toward humans that quickly… wow."

Miraculously, Belyaev had compressed thousands of years of domestication into a few years. But he wasn't just looking to prove he could create friendly foxes. He had a hunch that he could use them to unlock domestication's molecular mysteries. Domesticated animals are known to share a common set of characteristics, a fact documented by Darwin in The Variation of Animals and Plants Under Domestication. They tend to be smaller, with floppier ears and curlier tails than their untamed progenitors. Such traits tend to make animals appear appealingly juvenile to humans. Their coats are sometimes spotted—piebald, in scientific terminology—while their wild ancestors' coats are solid. These and other traits, sometimes referred to as the domestication phenotype, exist in varying degrees across a remarkably wide range of species, from dogs, pigs, and cows to some nonmammalians like chickens, and even a few fish.

Belyaev suspected that as the foxes became domesticated, they too might begin to show aspects of a domestication phenotype. He was right again: Selecting which foxes to breed based solely on how well they got along with humans seemed to alter their physical appearance along with their dispositions. After only nine generations, the researchers recorded fox kits born with floppier ears. Piebald patterns appeared on their coats. By this time the foxes were already whining and wagging their tails in response to a human presence, behaviors never seen in wild foxes.

Driving those changes, Belyaev postulated, was a collection of genes that conferred a propensity to tameness—a genotype that the foxes perhaps shared with any species that could be domesticated. Here on the fox farm, Kukekova and Trut are searching for precisely those genes today. Elsewhere, researchers are delving into the DNA of pigs, chickens, horses, and other domesticated species, looking to pinpoint the genetic differences that came to distinguish them from their ancestors. The research, accelerated by the recent advances in rapid genome sequencing, aims to answer a fundamental biological question: "How is it possible to make this huge transformation from wild animals into domestic animals?" says Leif Andersson, a professor of genome biology at Uppsala University, in Sweden. The answer has implications for understanding not just how we domesticated animals, but how we tamed the wild in ourselves as well.

There's much more at the link.  Recommended reading.

Thanks, Chris, for a very useful suggestion.  It's given me a lot of food for thought.



skreidle said...

See also:
- Opinion: We Didn’t Domesticate Dogs. They Domesticated Us. [NatGeo, 2013-MAR]

- Why Dogs are More Like Humans Than Wolves [Smithsonian Magazine]

- Why Dogs Are Smarter Than Cats [WSJ]

Anonymous said...

This is one of the first major experiments to document epigenetics. Darwinian selection of the genome is too slow to account for the speed of these changes, so a special type of genetics has been described.

Looking for it more widely, we see the same thing in humans, with children born during times of famine having more tendency to store fat than children born in the same country in less austere days. They also are more prone to develop what we've come to call metabolic syndrom.

Silicon Graybeard @ work

Anonymous said...

Dogs domesticated themselves. The jury is in.

It is likely that dogs 'domesticated' rapidly, as they self-selected, meaning that those that could tolerate proximity to humans (mobile humans that left heaps of garbage in their wake - nothing much has changed in that respect), were more likely to make with their 'kind', again due to proximity. Ergo, you get more and more 'tame' wolves and finally, voila, dogs that come right into camp.

The idea that someone would bring a 'wild wolf pup' into the cave for little Moog to play with is ludicrous on the surface and becomes even more ludicrous as you dig deeper.