Man’s Best Friend For 32,000 Years (and Counting)

Dogs and humans share a mutual desperation for each other’s attention. According to a study in Nature Communications, scientists estimate that dogs and humans have been best friends for quite some time; they’re talking, 32,000 years!

By sequencing the genomes of our hairy best friends – dogs – and comparing them with their even hairier ancient ancestors – grey wolves – the researchers were able to determine when the two species diverged, uncovering which genes flipped their switch with the change.

To make things a little more interesting, they also compared dog with human genomes, concluding that we likely evolved together since we shared 32 genetic pairs! Hanging out in the same environment likely drove genes to evolve similarly in dogs and humans.

Although humans were a threat to grey wolves, at some point, say 32,000 years ago, something changed. When people got into agriculture, aggressive gray wolves – or bullies – would prey on the livestock, but wolves with passive temperaments – or softies – were more passive, walking and scavenging with us instead.

We kept the softies as companions because they did not post a threat to human survival. Genes like the kind carried by the softie phenotype were likely passed down through the process of natural selection because they aided in their survival, therefore, they are known as positively selected.

One of these positively selected genes, SLC6A4, is found in both dogs and humans, therefore we can definitely say that humans and their best friends share some neural processes. Genes give way to the production of proteins; in this case, it is a protein that transports serotonin, which is a neurotransmitter sometimes, referred to as the “happy hormone,” though that is a vast understatement.

In humans, variations in SLC6A4 are responsible for aggressive behavior, obsessive-compulsive disorder, depression and autism. In dogs, the associated receptor and its downstream metabolite, or waste product, is correlated with the bullying trait I mentioned earlier. Interestingly, dogs respond to drugs used on humans to treat depression via serotonin receptors.

My first reaction to this environment driven gene sharing was, oh god! If the first shift occurred with the development of agriculture, what will happen to us all in the next 32,000 years? We now have the industrial and Internet revolutions to consider.

We lazily float in a digital world, which makes us increasingly immobile and therefore unhealthy. Since our world is also littered with processed foods, chemicals and antibiotics, how will these drastic shifts in environment change things for us in the years to come? And what about the doggies, will they be impacted too? Will we both become increasingly obese and diseased?

I think the dogs will be all right. Luckily, we’ve been selectively breeding them for years and will likely provide them with genes that will help them survive in our evolving world. Who knows, if we become cyborgs one day, we might make our dogs cyborgs as well.

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