The Dance of Fitness: Unraveling the Calculus Behind Human Flightlessness

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Have you ever wondered why humans can't grow wings and fly like birds? Or why some animals are faster, stronger, or smarter than others? The answer lies in the concept of fitness score, which is a measure of how well an organism can survive and reproduce in its environment. In this blog post, I will explain what fitness score is, how it is calculated, and how it relates to why humans can't grow wings.

Fitness score is a term used in evolutionary biology to describe the relative success of an organism in passing on its genes to the next generation. Fitness score can be influenced by many factors, such as physical traits, behavior, mating preferences, and environmental conditions. Fitness score can be calculated using different methods, depending on the context and the data available.

One common method of calculating fitness score is based on the concept of maximum oxygen uptake (VO2max), which is the most precise measure of overall cardiovascular fitness. VO2max is the maximum amount of oxygen that an individual can use during intense exercise. It reflects the ability of the heart, lungs, and muscles to work together efficiently. VO2max can be estimated using a simple formula that takes into account age, waist circumference or body mass index (BMI), leisure-time physical activity, and resting heart rate.

Another method of calculating fitness score is based on the concept of body composition, which is the proportion of fat and lean mass in the body. Body composition can be measured using different techniques, such as bioelectrical impedance analysis (BIA), dual-energy X-ray absorptiometry (DXA), or skinfold calipers. Body composition can be used to estimate fitness score using a linear regression model that takes into account weight, skeletal muscle mass (SMM), and fat percentage.

Fitness score is a useful concept to understand how natural selection works. Natural selection is the process by which organisms with higher fitness score tend to survive and reproduce more than those with lower fitness score. Natural selection leads to adaptation, which is the gradual change in the characteristics of a population over time in response to environmental pressures.

One of the environmental pressures that affects fitness score is gravity. Gravity is the force that pulls objects toward the center of the earth. Gravity affects the energy cost of movement, especially for flying animals. Flying animals need to overcome gravity by generating lift, which is the force that pushes them upward. Lift depends on the shape, size, and speed of the wings. The larger and faster the wings are, the more lift they can produce.

However, larger and faster wings also have a trade-off: they require more energy and more muscle mass to operate. This means that flying animals need to have a high metabolic rate and a low body weight to maintain flight. For example, birds have hollow bones, air sacs, and feathers that reduce their weight and increase their lift. They also have a four-chambered heart and a high respiratory rate that allow them to deliver oxygen to their muscles efficiently.

Humans, on the other hand, have a different body plan that is not suited for flight. Humans have solid bones, no air sacs, and hair that add to their weight and reduce their lift. They also have a two-chambered heart and a low respiratory rate that limit their oxygen delivery to their muscles. Therefore, humans would need to have extremely large and powerful wings to overcome gravity and fly. However, such wings would also increase their energy cost and muscle mass to an unsustainable level.

Therefore, humans can't grow wings because it would not increase their fitness score in their environment. In fact, it would decrease their fitness score by making them less efficient at other activities, such as walking, running, or climbing. Humans have evolved other adaptations that increase their fitness score in their environment, such as bipedalism, opposable thumbs, and large brains.

Fitness score is a measure of how well an organism can survive and reproduce in its environment. Fitness score can be calculated using different methods, such as VO2max or body composition. Fitness score relates to why humans can't grow wings because growing wings would not increase their fitness score in their environment. Instead, it would decrease their fitness score by making them less efficient at other activities.

I hope you enjoyed this blog post and learned something new about fitness score and why humans can't grow wings. If you want to learn more about this topic or other topics related to evolution and biology, you can check out these references:

: https://www.ntnu.edu/cerg/vo2max
: https://www.mayoclinic.org/healthy-lifestyle/fitness/in-depth/fitness/art-20046433
: https://fitness.stackexchange.com/questions/25608/body-composition-analyzer-how-to-calculate-the-fitness-score