Through the process of evolution, the human body has developed a highly adaptable digestive system. The high stomach acidity helps us efficiently digest various types of food, including those that may harbor harmful bacteria.
In the long evolutionary journey of humankind, adaptation and gradual changes in body structure and physiological functions have been key to our continuous adaptation to the environment, survival, and reproduction. Among these phenomena, a notable fact is that the acidity in the stomach of modern humans is almost similar to that of certain scavenger species. This discovery not only challenges our traditional understanding of the food chain and physiological functions but also reveals a lesser-known period in human evolutionary history.
Stomach acid helps break down proteins in food into smaller molecules for easier absorption by the body. The strong acidic environment in the stomach helps kill most bacteria, viruses, and parasites found in food, protecting the body from infections.
Under normal circumstances, the pH value of human gastric juice is maintained between 0.9 and 1.5, creating a highly acidic environment that is crucial for food digestion, nutrient absorption, and bacteria eradication. This value is almost equivalent to the acidity found in the stomachs of scavenger animals. For example, the pH of vulture gastric juice can be around 1 or even lower. This environment helps them eliminate bacteria and parasites present in carrion, thus ensuring survival in conditions of poor food availability and high infection risk.
Surprisingly, although humans are not typical scavengers, our stomach acidity is similar to that of scavenger species. This has prompted scientists to compare the gastric acidity among various carnivorous and omnivorous animals. The results indicate that scavenger species have the highest gastric acidity, followed by carnivores, omnivores, and finally herbivores. Humans, despite being omnivores, have gastric acidity that closely resembles that of scavengers, which is unusual and noteworthy.
To understand this phenomenon, we need to consider the evolutionary process of humans from millions of years ago. Approximately 7 million years ago, our ancient ancestors began evolving from ape-like creatures into upright walking humans. During this time, diversifying food sources was a crucial factor in the evolutionary process. Our ancestors likely did not hunt fresh prey as we do today but relied more on foraging, gathering, and even consuming leftover carrion from other animals.
Through the process of evolution, the human body has developed a highly adaptable digestive system. The high stomach acidity helps us efficiently digest various types of food, including those that may harbor harmful bacteria.
Research from 2016 showed that the remains of animals like zebras, after being hunted and left by large predators, can still provide a substantial amount of food, particularly bone marrow and brain, which are nutrient-rich parts. For our ancestors, these food sources were invaluable, helping them survive through periods of scarcity. Thus, the evolutionary process promoted the development of a highly acidic stomach environment, enabling our ancestors to effectively digest these food types and prevent bacterial spread.
As our ancestors began consuming more meat, their stomachs required higher acidity to digest and kill bacteria. This process did not happen overnight but gradually occurred alongside changes in diet and habitat. High stomach acidity not only improved human digestion but also enhanced disease resistance, which was especially important in the harsh environments of the evolutionary period.
High stomach acidity is an evolutionary trait that helps humans adapt to a diverse diet and protects the body from pathogens. Comparing with scavenger species helps us better understand the crucial role of stomach acid in the digestion process.
Today, human lifestyles have changed dramatically compared to our ancient ancestors. The abundance and variety of food, along with medical advancements, have altered stomach acidity to some extent. Medications such as antibiotics, along with exposure to chemicals, can impact the gut microbiota, thereby affecting stomach acid secretion. Additionally, unhealthy habits like drinking alcohol, smoking, and irregular diets can also negatively affect the digestive system.
The similarity of human stomach acidity to that of scavenger species is evidence of a complex and fascinating evolutionary process. From the scavenging times of our ancient ancestors to modern lifestyles today, changes in gastric acidity reflect the physiological adaptations of humanity throughout historical stages. This not only helps us gain a better understanding of our own evolutionary process but also opens new avenues for research in physiology and medicine in the future.
