During the painstaking process of domestication that lasted for thousands of years, the wolves that became man’s best friend went through a series of irreversible mutations – in other words, they evolved. 

These mutations were often good and benign and helped these animals adapt to life with humans – they became able to digest our leftovers, which were very different from what they were used to eating in the wilderness, and they became more docile. However, since the process of evolution is never perfect and a lot of “mistakes” can happen, this brought about a myriad of harmful mutations that our furry friends, unfortunately, have to live with today.

According to various studies, this happened due to selective breeding. Naturally, people figured out that if they only bred dogs with desirable traits, they would have offspring with the same traits. That’s why we created various breeds that look nothing like their wolf ancestors, including the poodle, the pug, the dachshund, and many others.

No matter how popular these breeds are today, centuries of selective breeding have left them with serious genetic mutations, which make them susceptible to more than a few diseases and disabilities. Another factor to consider here is population control which led to a decrease in population size. A smaller population means there’s less room for evolution to correct faulty genetic mutations caused by domestication.

Kirk Lohmueller of the University of California, Los Angeles led a study that analyzed sequence data from the genomes of 25 semi-feral “village dogs” from ten different countries, 46 breed dogs and 19 gray wolves. They discovered that dogs had an estimated 115 more deleterious alleles than wolves, and 2.6% more deleterious variants. This is often associated with lower reproductive fitness in animals.

Lohmueller’s work with dogs can help us better understand how human evolution works and how we might have done something similar to ourselves. Just as dogs have been the “victims” of a reduced population size, the same has happened to us when we left Africa and spread across the globe. Of course, this is a controversial topic, but it’s something to be aware of, nevertheless.

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