‘The Roof of the World’ is a pretty groundbreaking nickname, don’t you think?
Tibet is given this nickname because this Asian country sits on the world's highest plateau. It is surrounded by the highest mountains on Earth-- Mount Everest, which boasts an elevation of 29,029 feet above sea level.
The high altitude in Tibet also means the air is thinner with limited oxygen supply. While many of us might struggle to live at such altitudes, it appears a particular species of dog has successfully adapted to these conditions.
The Tibetan Mastiff
Dogs are universally known as man’s best friend. From the Shih Tzu in China to the Great Dane in Germany, dogs have made their adorable presence known worldwide.
In Tibet, we have the large and furry Tibetan Mastiffs. They were primarily watchdogs that protect sheep and other livestock from wild animals like wolves and leopards, as well as guard monasteries and palaces.
Researchers in China have found out how the Mastiffs are able to withstand Tibet's harsh weather. These dogs have two genes known as EPAS1 and HBB which link them to gray wolves. EPAS1 is a gene that produces less hemoglobin, which prevents a blood clot or stroke where there is limited oxygen. HBB is a gene found in several other animals that live in similar environments.
This study shows that the Mastiffs interbred with gray wolves that lived in these high altitudes since other breeds of Chinese dogs lack these genes. Interestingly, the people who live in Tibet also adapted to the rare-air conditions by interbreeding with Denisovans, an ancient species of humans (earlier article here).
Let’s Get Into The Science...
Let us quickly recap what we know so far…in order to adapt to the harsh conditions, Tibetan dogs interbred (as did humans) in order to acquire more ‘desirable’ traits that allowed them to withstand these specific weather conditions.
For many of us, our idea of evolution is a straight line – species meets a new environment, adapts, develops a mutation and survives. Their offspring survive too, as this advantageous mutation is passed down. However, this is a slow process (two million years to be exact), and for the Tibetan people and their dogs, time was of the essence. That is why instead of sitting around waiting for a mutation to happen, they acquired this gene through interbreeding.
Wait so, how did the gray wolves get this gene then? Let’s talk about random mutations. In any population, not everyone would have the same set of genes. In fact, there will be many variations of genes. So under new conditions, there would be many different mutations allowing some to survive and adapt quicker.
Had the Mastiffs reproduced only within themselves, a random mutation would not be able to occur due to lack of genetic diversity. And although they could have adapted over time, they most likely would have died out first. Isn't it interesting how species survive!