Yaks—Living the High Life

The Tibetan plateau is the roof of the world. Rising three miles into the sky, the air is intolerably thin, water is scarce, and temperatures regularly plummet to –40°F. No trees peep above the rocky, windswept landscape. Even hardy shrubs struggle to survive.

Yet there they are, lots of them—massive hairy yaks munching away on meager scraps of grass and herbs, seemingly oblivious to their impossible situation. Wild males can be over 10 feet (3.25 m) long and tower over 6.5 feet (2 m) at the shoulders; their average weight is around 1 ton (1,000 kg).

With its dense, woolly undercoat and shaggy outer hair coat, the “grunting ox” (Bos grunniens) is well prepared to endure the raging cold that is characteristic of this remote region of Asia. Yaks can easily withstand temperatures of –40 degrees, that numbing condition where the Fahrenheit and Celsius readings are the same . . . if the thermometer goes that low. They have been seen bathing in lakes and rivers, regardless of the temperature.

These are cattle, but not like the barnyard variety you’re used to. Wild yaks are among the largest living members of the cattle family. (Females are about a third the size and weight of males.) Despite their intimidating stature and impressive horns, yaks are on the timid end of the cattle spectrum. They prefer to run away when they encounter humans.

Not only must they survive the cold, but they must function in the thin mountain air. Their home range is 12,800 to 19,200 feet (4,000 to 6,000 m) above sea level, where oxygen is limited and plant life is sparse. Few animals can survive at this altitude. Thanks to their caring Creator, however, yaks are adapted to their home high on the Tibetan plateau in a variety of ways.

They have a stocky build with short legs and broad hooves, making them excellent climbers as they travel great distances searching for food. They have a larger heart and lungs than cattle living at lower altitudes, enabling them to pump more blood and take in more air than others of their kind. Additionally, they continue to produce the specialized hemoglobin that they had in their mother’s womb because it enables them to extract more oxygen from their lungs and deliver it to body tissues despite these challenging conditions (more on that later).

• Learn more about Tibetans.

The success of yaks in the high Himalayas has made it possible for humans to settle there, too. In fact, yaks have been kept as livestock for thousands of years. Unlike their wild cousins, which are dark brown to black, domestic yaks are much smaller and come in a wider variety of colors. They are central to the life of people living at high altitudes, especially to the Tibetans. Yaks provide milk, fiber, and meat. Their dried dung is ready-made fuel. They serve as beasts of burden and can even be ridden. In some regions, yak racing is a traditional form of entertainment at festivals.

Where Do Yaks Come From?

As far as we know, such high mountain ranges did not exist before Noah’s Flood. The Himalayas are made of fossil layers that were deposited by the Flood waters, and then the moving earth pushed up these layers into the ranges we see today. So how did such well-designed creatures happen to inhabit this cold, remote region, thousands of miles from Ararat?

The Bible informs us that God originally created all the creatures of the earth “according to their kinds” (Genesis 1:20–28). Every kind of land animal was created on Day Six, the same day as man. While we are not given detailed information, we do know that these creatures were to reproduce and fill the earth. This filling occurred not only after Creation but again after the survivors on the Ark spread over the earth following the global Flood (Genesis 8:15–19).

The biblical account seems to imply that creatures reproduce only according to their kinds. That’s certainly what we observe today, and have always observed. Since yaks can produce offspring with European domestic cattle and their relative, the American bison, it appears they must be in the same created kind. Other members of this kind include African buffalo, zebu cattle, and the gaur of Southern Asia. Indeed the cattle that left the Ark have reproduced and filled the earth, from grassy plains to tropical rainforests and frigid mountains!

The earliest fossil evidence of yaks comes from the Pleistocene, the time of the Ice Age after the Flood. Mention of yaks is common in Chinese documents dating from the fourth century BC. From these records it is clear that domestic yaks had already become extremely important in the lives of the Qiang people who raised them. It is doubtful that these people ever could have colonized the Tibetan plateau if it had not been for these animals.

Variety Packed into a Kind

It is clear that God designed certain features of this creature to vary so they would be equipped to fill many different habitats. Height, weight, and body proportions are obvious examples. Hair length, hair density, and color can vary too. Some of this variation was created, yet even more variation has arisen in some traits (such as certain coat colors, attributable to mutations), as creatures have reproduced and filled the earth.

Only an infinitely wise designer could build something that involves such infinitely detailed forethought.

Variations in these and other features not only enable the animals to adapt, but can be beneficial to humans as we rely on these creatures to meet varying needs. For example, the hair coat on the yak not only allows it to survive cold temperatures, but is useful to humans. The woolly undercoat makes soft, warm clothing to fight off the bitter cold. It can easily be brushed out of the animals’ coat when they shed in the spring. Herders can shear the longer hairs to make belts or rope. No wonder the yak is a popular animal in Asia’s mountainous regions!

Yaks have become specialized for life at high altitudes. They now thrive in regions where other cattle would struggle to survive. However, this specialization limits them in other ways. For example, yaks would not survive well in the hot, arid climates to which zebu cattle have adapted.

Most cattle are now specialized, including our common domestic cattle: some are bred to produce lots of milk, while others produce meat. They excel at what they are specialized in, but often at the expense of good performance in other areas. No one creature can excel in everything simultaneously, so God allows humans to breed cattle varieties with many different characteristics.

Specialized Blood for High Altitudes

A number of components are involved in adaptation to high altitudes; one that is well studied is changes in hemoglobin. Hemoglobin is a special protein in red blood cells that binds to oxygen so it can be carried through the bloodstream and delivered to the body.

This process is a bit more complex than it sounds. Hemoglobin needs to bind tightly to oxygen when it picks up the oxygen, but then it must be able to “let go” when the time comes to drop off the oxygen at the needy tissues. The ideal “grip” varies under different conditions.

Mammals normally produce several types of hemoglobin throughout life. Embryonic, fetal, and adult forms vary in how tightly they bind to oxygen. For example, fetal hemoglobin binds to oxygen more strongly than adult hemoglobin. This helps the developing baby “grip” more oxygen from the mother’s blood supply. Around birth the blood usually transitions to adult hemoglobin, since the source of oxygen shifts to the lungs.

Even after birth, how tightly hemoglobin needs to bind to oxygen shifts. Activities such as running or giving birth can change body temperature and pH, and this affects hemoglobin’s ability to bind to oxygen. To adjust for these variables, the body responds by producing chemical compounds, called cofactors, that adjust the strength of the binding. This complex system had to be in place from the very beginning for each individual to survive and for females to bear offspring successfully. This type of adjustment to body function is known as physiological adaptation. Other physiologic adjustments can occur to allow us to handle higher altitudes, should we visit places like Quito, Ecuador (9,300 feet [2,800 m] above sea level).

Yaks and other animals that are very well adapted to high altitudes have differences in their hemoglobin. The yak can produce two to four different types of adult hemoglobin, as well as two fetal hemoglobins. This is unusual, as most mammals would produce only one fetal and one adult hemoglobin. Further, the yak still produces some of the fetal hemoglobin during adulthood! This gives them more options for keeping up their oxygen supply.

Life: Designed by God to Respond to the Environment

Adaptation is a characteristic of life. Life responds in very controlled ways to its environment, which enables creatures to survive and thrive in a variety of environmental situations. This is not the same as evolving into a different type of animal, which would require more profound restructuring.

Many of these adaptive changes occur within the lifetime of the creature. For example, all mammals have a complex network of sensory organs and nerves that can adjust various parameters, including the levels of cofactors in the blood to alter the “grip” of hemoglobin in response to changing conditions. Exercise, pregnancy, and changes in oxygen levels all trigger coordinated changes within the body.

Since a “one-size-fits-all” sequence for hemoglobin does not exist, God designed creatures with different options for different life stages. This demonstrates the amazing foresight and care of the Creator; animals would not be able to reproduce without it. The amazing complexity of this controlled physiological adaptation is awe-inspiring indeed!

Evidence of a Caring Creator

The world around us gives testimony to its awesome Creator (Romans 1:20). Although stories can be concocted suggesting that naturalistic mechanisms were sufficient to bring about this incredibly expert design, there is no known mechanism by which this can happen. Only an infinitely wise designer could build something that involves such infinitely detailed forethought.

Certainly variations are obvious within the cattle kind, as in many other kinds. Yaks have been designed with a number of features that help them adapt to the cold mountainous regions. These well-coordinated variations can only reasonably be attributed to a Creator who intentionally designed His creatures with mechanisms to respond to changing conditions and fill the earth.

While these changes are amazing, the creatures are not changing from one kind of animal into another. Instead, they show that one kind of animal is empowered to fill the earth with many specialized species as God intended. The changes also provide useful byproducts and delightful variety for humans to enjoy, as they care for these gifts from the Creator.

Natallia Yaumenenka | Thinkstockphotos.com

People Made for the Mountains

At 13,000 feet, oxygen levels are 40 percent less than at sea level. Most people tire quickly and develop headaches. The body responds by producing more red blood cells, which carry oxygen in the blood. But this change can lead to mountain sickness, including headaches, dizziness, and nausea.

It’s a huge problem for mountain climbers. When Europeans began flocking to the Himalayas to climb the world’s highest mountains, they were surprised to find that local Tibetans didn’t have problems with low oxygen. They wisely brought along Tibetans as guides. In fact, a Tibetan (from a tribe known as the Sherpas) stood beside Sir Edmund Hillary when he reached the summit of Mount Everest in 1953.

Later studies found that Tibetans enjoy an adaptation that does not exist among people who live at lower altitudes. For one thing, Tibetans have a higher breathing rate when at rest, which allows them to draw more oxygen. Interestingly, they have the same number of red blood cells as people living at low elevations, which protects them against mountain sickness.

Tibetans have the same hemoglobin as everyone else. (Hemoglobin is the oxygen-carrying molecule in red blood cells.) But another gene that controls the body's response to altitude has changed. Mutation in Tibetan DNA changes how their bodies control the “super athlete gene” (EPAS1). This gene produces a protein that senses oxygen levels and adjusts other systems in the body to compensate when levels fall too low.

How did Tibetans acquire this change, even though they’ve lived on the Tibetan plateau for only three thousand years? Clearly, God designed our bodies to make carefully controlled changes, as Noah’s descendants moved to different environments on earth.

Extreme cold

Temperatures can plummet to -40°F, which would kill most mammals. But yaks are designed to retain heat.

• Compact body with short neck, short legs, small ears, and short tail
• Thick coat of coarse outer hair
• Insulating undercoat of fine down
• Layer of fat under the skin
• Sweat glands turned off except for the muzzle

Low oxygen

Oxygen levels are 40% lower than at sea level. So yaks have special designs to gather extra oxygen.

• Large chest to breath more oxygen
• 1–2 more pairs of ribs than cattle (14–15 total)
• Large lungs to absorb more oxygen
• Large heart to pump more oxygen
• Specialized hemoglobin to grab more oxygen
• High breathing rate

Difficult terrain

The Tibetan plateau is covered with dangerous cliffs and marshes. So yaks are built for sturdiness.

• Sturdy, forked hooves
• Short, strong legs
• Calm temperament to face dangers

Limited food

The limited growing season forces yaks to eat whatever is available—not just grass like other cattle, but also shrubs. They have teeth and a stomach for both!

• Large rumen (digestive organ) to graze lots of grass
• Thorny tongue to grab tall grass
• Flat front teeth to bite off shorter plants close to the ground
• Thin, flexible lips to pull shrubby plants

Solar radiation

The high, thin atmosphere doesn't block deadly radiation from the sun. So yaks have dark colors to block the sun's rays.

• Dark pigments in skin
• Predominantly black hair