From: https://www.insidescience.org/news/rare-human-syndrome-may-explain-why-dogs-are-so-friendly

Rare
Human Syndrome May Explain Why Dogs are So Friendly

Dogs and people with Williams syndrome may both owe
their sociable
personalities to changes in the same genes.

Dog.jpg

Image credits:

Sergey Lavrentev via Shutterstock

CREATURE

Wednesday, July 19, 2017 - 14:00

Nala Rogers, Staff Writer

(Inside
Science) -- When it comes to sheer friendliness, few humans can match the
average dog. But people with Williams syndrome may
come close, their unusual genetics granting them a puppyish zeal for social
interaction. Now, scientists have found that extreme friendliness in both
species may share common genetic roots.

A friendly condition

Williams syndrome, also known as
Williams-Beuren syndrome, occurs when people
are missing of a chunk of
DNA containing about 27 genes. The syndrome affects about one in 10,000 people, and it is
associated with a suite of mental and physical traits, including

·
bubbly, extroverted
personalities,

·
a broad forehead,

·
full cheeks,

·
heart defects,

·
intellectual
disability and

·
an affinity for music.

The first hint of a link between
dogs and Williams syndrome came in 2010, when
evolutionary biologist Bridgett vonHoldt and her colleagues examined DNA from
225 wolves and 912 dogs from 85 breeds. They were looking for parts of the
genome that have been shaped by selection since dogs diverged from wolves.

One gene that popped out was WBSCR17, suggesting that
it or other genes near it were important in dog evolution. This region of the
genome is similar in dogs and humans, and the human version of WBSCR17 is
located near the sequence that is deleted in people with Williams
syndrome.

Doggie DNA

In the new study, vonHoldt, now an
evolutionary biologist at Princeton University in New Jersey, and her
colleagues took a closer look at the region surrounding WBSCR17. First, they
tested the friendliness of 18 dogs and 10 wolves, all raised with regular
attention from human caretakers. They measured how much time each dog or wolf
spent within a 1-meter radius of a human, as well as how hard the animal worked
to solve a puzzle box.

As expected, wolves spent less time near
humans, and most worked equally hard to solve their puzzle box regardless of
whether a human was present. In contrast, dogs tended to look at the human
instead of the puzzle box, focusing on the puzzle only when left alone.

While dogs were more sociable than wolves on
average, individuals varied, with some wolves acting more friendly and some
dogs acting more aloof. When the researchers analyzed DNA from 16 of the dogs
and eight of the wolves, the behavioral differences turned out to be correlated
with variations in three genes -- the WBSCR17 gene highlighted in the 2010
study, and two additional genes from within the canine equivalent of the
Williams syndrome region.

For each of these three genes, the researchers
found multiple variants that differed in structural ways, such as whether or
not they contained an extra sequence of DNA. Some gene variants were found
mostly in the friendly dogs and wolves, while others were found more often in
unfriendly animals.

While personality traits like friendliness are
probably shaped by hundreds or thousands of genes, these three genes appeared
to play a surprisingly large role in controlling social behavior, said
vonHoldt.

"Some of these structural variants could
explain a huge shift in a behavioral profile -- that you go from being a wolf-like, aloof
creature, to something that's obsessed with a human," she said.

When the researchers examined those same three
genes in 201 dogs from 13 breeds, they found similar patterns of genetic variation
between breeds traditionally associated with friendly behavior, and breeds
generally considered to be more standoffish.

Same genes, different species

Two of the genes, GTF2I and GTF2IRD1, had
previously been linked to social behavior in mice as well as in people with Williams syndrome. In 2009, Uta Francke and her colleagues
at Stanford University in California found that mice were unusually eager to socialize when they
were missing those two genes. But until Francke saw the new study, she had no
idea that the genes she had studied might help explain the behavior of her own
dog, a Bernese mountain dog named Minna.

"She walks up to strangers and wants
interaction with everybody, just like the Williams kids," said Francke,
who has worked with people with Williams syndrome in
her career as a medical geneticist. "To think that this is because of the
involvement of these genes in some way -- I find that extremely exciting."

The connection between dogs and Williams
syndrome will likely ring true for people within the Williams syndrome
community as well, said Jocelyn Krebs, a biomedical researcher at the
University of Alaska Anchorage who has studied Williams
syndrome and was not involved in the new study. Krebs has a son with Williams syndrome, and she sits on the Williams syndrome Association board of
trustees, so she knows how friendly people with the condition can be.

"If they had tails, they would wag
them," she said.

Dogs2.jpg

Soren Wolf via Flickr

CC BY-ND 2.0

Roots of domestication

The findings are consistent with current
theories of dog domestication. Once, researchers assumed that ancient humans
domesticated dogs on purpose, adopting wolf pups and breeding them for useful
traits. Biologists Ray and Lorna Coppinger have pioneered a different view, seeing early dogs
as scavengers on human trash. According to this theory, shy wolves continued to
hunt in the forest, while bolder wolves that could tolerate humans took up
residence at village rubbish heaps.

Ray Coppinger himself avoids words like
"friendly" when referring to these ancestral dogs. But according to
Clive Wynne, a behavioral scientist at Arizona State University in Tempe,
Arizona, and one of the new study's authors, sociability could have been a key trait that helped early
dogs get access to human scraps. The new study suggests that dogs
achieved that friendliness in part through changes to the genes that are
equivalent to those affected in people with Williams
syndrome.

"Outside of, like, Disney movies, animals
all just making friends with each other and being lovey-dovey out in the forest
is pretty much a catastrophe," said Wynne. But, he said, "If you have
a mutation that makes you more willing to make friends, well then, you're going
to get a lot more out of the trash dump."

Wynne can’t say for sure whether the
domestication process happened at multiple villages at different times, or if
it happened just once, as indicated by another recent study that looked at DNA from
ancient dog fossils.

It's too soon to know just how important the
genes identified in the study were in dog domestication, cautioned Ray
Coppinger, during an interview with Inside Science. But it's possible that they
played a pivotal role, not just for dogs, but for other species as well, said
Carlos Driscoll, a geneticist who studies cat domestication at the National
Institutes of Health in Rockville, Maryland. The next step, said Driscoll, is to test other
domestic species, and see whether the same three genes may contribute to tame
temperaments in everything from cats to goats.

"The only thing that's common among all
domesticates is that they're sociable -- that they get along with people,"
said Driscoll. "This very strongly suggests that this region and these
genes are important in domestication."

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Author Bio & Story
Archive

Nala Rogers

Nala Rogers is a staff writer and editor at
Inside Science, where she covers the Earth and Creature beats. She has a
bachelor’s degree in biology from the University of Utah and a graduate
certificate in science communication from U.C. Santa Cruz. Before joining
Inside Science, she wrote for diverse outlets including Science, Nature,
the San Jose Mercury News, and Scientific American. In
her spare time she likes to explore wilderness.