Why are some dogs better at paying attention to humans, particularly human gestures like pointing, than others? We know genetics has something to do with it, because some breeds (like border collies) are a lot better at responding to human signals than others like beagles. To better understand the biology driving differences in ability to respond to human signals, researchers at the Family Dog Project compared dogs and wolves as they grew up. They knew that wolves can respond to human signals, but that they are better at this when they have been extensively socialized, whereas dogs can understand human signals with much less socialization. But at what age do these differences manifest?
Image from the Family Dog Project
The researchers used a pointing test to measure ability to respond to human signals. This test has been used on dogs before: if a dog is given a choice of two bowls, only one of which contains food, and he can't see where the food is, will he follow a person's pointing gesture to pick the right bowl? (The bowl with no food in it is rubbed with food so the dogs can't use their noses to get the right answer.) This test has been done in the past with dogs versus human children (dogs do about the same as two year old kids on this task), dogs versus wolves (dogs generally outperform wolves, unless the wolves have a whole lot of experience with humans), and dogs versus chimpanzees, our closest primate relatives (dogs outperform chimps!).
For this study, the researchers compared hand-reared (i.e., well socialized) 8-week old dog and wolf puppies; 4 month old dog and wolf puppies; and adult dogs and wolves. They tested the animals' abilities both with "proximal" pointing (putting their finger right up to the bowl) and "distal" pointing (standing farther away and indicating the bowl) - except that, since very young puppies and wolves don't see well, they didn't test the distal pointing in the 8 week old babies. What they found:
The 8 week old puppies (dogs and wolves) had similar ability to follow the proximal pointing gesture with the researcher's finger right next to the bowl. However, 6 of the 13 wolf puppies tested had to be removed from the trial because they couldn't be held on the start line or didn't go choose a bowl. Of the 9 puppies, only one was removed for similar reasons.
4 month old dogs did better at distal pointing (with the researcher standing away from the bowl and indicating it) than 4 month old wolves did. In fact, the 4 month old wolves seemed to do no better than chance.
Adult dogs and wolves did equally well with both proximal and distal pointing.
- At all three ages, wolves needed more time to establish eye contact with the pointing human than dogs did.
So all the animals at all ages were able to understand a pointing gesture when the human put their hand right up to the bowl. But pointing from farther away was harder, as you'd expect. Very young puppies (dog and wolf) were not tested on that task. At four months, wolves hadn't figured it out yet, but dogs had. As adults, the wolves had caught up. These were highly socialized adult wolves with a great deal of experience with humans.
It's interesting that dogs seem to develop the ability to understand a more difficult human pointing gesture at a younger age than wolves - and particularly interesting that this may have to do with the fact that wolves are not as eager to look us in the eye as dogs are. (If you don't look at someone, it's hard to follow their pointing gesture!)
So what does this mean for differences in different dog breeds? Do different dog breeds have differences in the timing of their cognitive development? Does this affect how much attention they pay to us, and perhaps how easy they are to train? We don't know, but differences in puppy development across breeds are something Darwin's Dogs is very interested in.
(By the way, check out the original paper - it's open access, and has some great videos of dog and wolf puppies at the end!)
Gácsi, Márta, et al. "Explaining dog wolf differences in utilizing human pointing gestures: selection for synergistic shifts in the development of some social skills." PLoS One 4.8 (2009): e6584.