The understanding of altitude sickness and its effects on the human body evolved with the discovery of atmospheric pressure and oxygen.
Experiments conducted by scientists like Robert Boyle and Robert Hooke using air pumps and decompression chambers helped reveal the physiological responses to low air pressure at high altitudes.
Advancements in anatomical dissections and illustrated anatomy books contributed to the understanding of how the body functions, although the specific mechanisms of altitude sickness remained unclear.
Living at high altitudes presents challenges such as hypobaric hypoxia and limited resources, but genetic adaptations in humans and animals have developed to cope with these conditions.
Deep dives
The Discovery of Atmospheric Pressure and Oxygen
The history of understanding altitude sickness and its effects on the human body can be traced back to the discovery of atmospheric pressure and oxygen. Scientists, such as Evangelista Torricelli and Blaise Pascal, developed the first barometers to measure atmospheric pressure. This led to the understanding that the air exerts pressure and that pressure changes with altitude. With this knowledge, it became clear that the decrease in atmospheric pressure at higher altitudes could affect oxygen levels and thus impact human health.
Early Observations of Altitude Sickness
Ancient texts from China and accounts from European explorers in the 16th and 17th centuries describe the symptoms of altitude sickness. These include headaches, nausea, dizziness, and fatigue, among others. However, the understanding of the underlying causes and mechanisms of altitude sickness was limited at this time.
Scientific Experiments and Discoveries
Scientists such as Robert Boyle and Robert Hooke conducted experiments to investigate the effects of low air pressure on animals and humans. They used air pumps and decompression chambers to simulate different altitudes and observe the physiological responses. These experiments helped shed light on the effects of altitude on the human body, although a complete understanding of the mechanisms was still lacking.
Linking Anatomy and Function
Advancements in anatomical dissections and the creation of illustrated anatomy books furthered the understanding of how the body functions. This led to the realization that the lungs play a crucial role in respiration and the circulation of oxygen-rich blood. However, the exact mechanisms of how altitude affects the body and leads to altitude sickness remained a subject of ongoing investigation.
The challenges and benefits of living at high altitudes
Living at high altitudes poses numerous challenges, including hypobaric hypoxia, low oxygen levels, extreme cold, UV radiation, and limited food availability. However, high altitudes also offer advantages, such as reduced predation and competition. Certain adaptations, like increased chest circumference and lung volume, help organisms cope with the harsh conditions.
Genetic adaptations to high altitudes in humans and animals
Humans and animals that have lived at high altitudes for generations show genetic adaptations to the environment. In the Andes, for example, people have developed larger chest circumference, higher hemoglobin and red blood cell concentrations, and altered genes related to oxygen transport. In the Tibetan Plateau, adaptations include lower red blood cell concentrations and higher levels of nitrous oxide in the lungs. Animal species, like deer mice, also exhibit genetic adaptations, such as enhanced oxygen-carrying capacity and improved oxygen utilization during shivering.
Unanswered questions and ongoing research in high altitude physiology
One of the biggest unanswered questions in the field of high altitude physiology is how genetic changes lead to physiological adaptations. Researchers are still exploring the mechanisms behind genetic mutations and their effects on an organism's physiology at high altitudes. Ongoing studies focus on understanding genes like E-Pass1 and their roles in regulating hypoxia response, as well as investigating the physiological and genetic aspects of fetal growth restriction and improved nutrient exchange in high altitude-adapted mammals.
In our episode on the bends, you joined us as we explored how low we can go. Now we’re back with a similar invitation: come along to learn how high we can fly (and what happens to our bodies when we get up there). In this very special episode, we examine the short-term effects and potentially deadly consequences of life at great heights and ask how we came to understand the relationship between altitude, oxygen, and health. This journey begins earlier than you may have guessed, back to a time before oxygen was discovered, and winds through unexpected avenues, including misadventures in hot air balloons and early experiments demonstrating the vitality of air, as we trace how the pieces of high altitude physiology were put together. A big part of what makes this episode so very special is our guest, Dr. Jonathan Velotta, Assistant Professor of Evolutionary Biology at the University of Denver, who joins us to chat about some of the incredible ways that humans and other animals have adapted to live at high altitude. Tune in for a bird’s-eye view of what it’s like to have a high life.
