Last week, I explored the theories behind the association of dogs with humans and vice versa, and briefly touched upon the amazing ability of dogs to read human faces and gestures. In this blog post, I will aim to explore the real science behind the evolution of dogs – the genetic changes that occurred and why Darwin was so perplexed by these mammals.
The geneticist Greger Larson who studies the genetic evolution of dogs at Oxford, states that up until the first domestication event, humans were not much different from any other primate – we just go about manipulating our current environments one by one. However, after that partnership, we became something else, we changed into the species we see today – billions of people, skyscrapers, climate change, and everything else that comes with it. Did dogs make us better?
With that first domestication event, something happened to turn the aggressive, timid, hunter grey wolf into a cute, adorable charming dog. Some scientists believe this only happened 10,000 years ago, whereas others believe it happened around 30,000 years ago, and some think it occurred in Europe, while others in the Middle East. Recent research suggests that all of these claims are correct, and dogs emerged from two independent wolf populations. So how do we get to the bottom of this debate? One way is to go straight for the genes and to look at the molecular evolution of dogs.
Much like the human genome project, the canine genome project is still ongoing, despite fully sequencing a high-fidelity script of a female boxer dog, Tasha. The project aims to point to genetic markers of disease in dogs, investigate questions involving the domestication of dogs, and explore similarities between dog breeds.
The domestic dog comes from a superfamily – Canidae, and is the most recently evolved of this family – which also includes that of bears, weasels, skunks and seals. Within the Canidae superfamily, there are 3 distinct groupings – 1) fox like canids, 2) wolf like canids, including dogs, wolves, coyotes, and jackels, and 3) the South American canids. Darwin and other renowned scientists once believed that the great diversity seen in the form and behaviour of dogs was due to shared ancestry with a number of wolves and other canids – resulting in different breeds. However, extensive genetic analysis has now shown that dogs are purely derived from the gray wolf only, rather than any other canids. This also means that the immense diversity in the domestic dog is relatively new, and is down to the existing genetic variation in the ancestral population of gray wolves and subsequent mutations that have occurred during the brief domestication period.
So how is there such breed diversity in the domestic dog? Well, partially due to the fact that the past 2 centuries have held one of the greatest genetic experiments humans could have ever performed – humans have encouraged the creation of different breeds, with institutes like the Kennel Club strictly categorising the physical characteristics of each breed. The diversity of the skeletal size and proportion of dogs is greater than any other mammalian species in the world – however, the genetic mechanisms behind this is not yet fully understood, but it is known that the variation between dog breeds is much greater than that between humans – (27.5% for dogs, 5.4% for humans). However, a breed of dog can be defined at the molecular level, implying that separate breeds are distinct genetic units.
So the Border Collie sitting next to you is a completely distinct genetic entity than the Golden Retriever keeping your feet warm! Fascinating stuff which once again reminds us why dogs truly are excellent. In my next section of “How to Make a Best Friend”, I’ll explore more behind the remarkable behaviour of dogs.
This is part one of a series of blog posts on the evolution and domestication on dogs by Dr Matthew Yates. Matt gained his PhD in 2014 studying the role of macrophage migration in neuropathic pain and atherosclerosis. His interests lie in psychobiology, haematology and dogs. He is currently working in a clinical haematology field