Dogs pick love over food
New Delhi: Dogs prefer human affection over food, says a study by Indian scientists that throws fresh light on the dynamics that might have facilitated the domestication of dogs.
The scientists at the Indian Institute of Science Education and Research (IISER), Calcutta, have shown that while stray dogs avoid making physical contact with unfamiliar humans, they tend to build trust on affection and not food.
The scientists tested 103 adult stray dogs, offering them food - a piece of chicken - and four pats on the head, a gesture of affection, to study their immediate and long-term response to both food and social reward, or affection.
In the first series of experiments, they found 63 per cent of the dogs preferred food rewards from the ground rather than from the hand of a stranger, showing a bias against making physical contact with humans.
However, they noticed that dogs' preferences to feed from the human hand increased with more and more exposure to the pats on their heads. Over time, it was the pats on the head that appeared to influence the dogs' tendency to make physical contact with humans - and not the food.
"Affection seems a more reliable way to acquire a dog's trust than food," said Anindita Bhadra, an assistant professor at the IISER who led the study. The findings have just been published in the Journal of Experimental Biology.
The other team members are Debottam Bhattacharjee, Shubhra Sau and Jayjit Das. They tracked dogs in Calcutta and Kalyani, near the IISER campus, and videographed each encounter.
Earlier studies have suggested that pet dogs prefer praise over food rewards when assessed on task performance, but no one has until now studied preferences of stray dogs.
The IISER study also points to an adaptation mechanism that might have contributed to the domestication of dogs from wild wolves tens of thousands of years ago when humans were still hunter-gatherers.
"Nobody really knows what exactly led to dog domestication," Bhadra said. "All we know is they became more friendly towards humans, more tame, less social among themselves, displaying reduced levels of pack instinct."
During the early stages of domestication, ancestors of present-day dogs would have faced situations where human communities would have been an attractive source of food as well as a threat.
"Imagine, an ancestor of present-day dogs hangs around humans and approaches people for food and gets beaten up, another strikes up friendship and trust through affection - the second is more likely to benefit in the long run than the first," Bhadra said.
The tendency of dogs to rely on social interactions for trust could have acted as a key driver in domestication.
Bhadra says understanding the dog-human relationship will be important to address the harms both do to each other. Stray dogs are the primary source of rabies in humans which continues to kill an estimated 20,000 people across the country each year. And stray dogs have high human-induced mortality caused by road accidents or beatings.