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Is man at the top of the food chain?

Lions, gray wolves and large white sharks have one thing in common. They are the hunters at the top of the food pyramid. Their diet is almost entirely composed of meat, and except in rare cases, these animals do not have natural predators (except humans). So, if we humans kill the hunters at the top of the food pyramid, does that mean we are at the top of the food chain?

The answer to this question depends on your definition of “hunter”. That is, whether you kill other animals to eat or kill them for other reasons, and whether you are considering prehistoric humans or modern humans.

“In ecology, or the study of how organisms relate to each other and their environments, the place of humans in the food chain is not determined by what we eat or what we kill, but by It is what we eat. According to this definition, the answer is no, humans are not hunters at the top of the food pyramid, because we do not eat everything we kill.

Bonomo and his colleagues at the IFREMER Institute decided to determine the human position in the food chain, also called the “nutritional level”. Scientists usually determine the level of nutrition on a scale of one to five. Plants and other primary producers that get their energy from sunlight are at level one, and vegetarians occupy level two. Meanwhile, Level 3 species eat only vegetarians and Level 4 species eat only Level 3 carnivores.

The nutritional level of the omnivorous species, which receive their food from different nutritional levels, is calculated by the average nutritional level of what they eat, plus one. For example, an animal that eats exactly 50% of plants and 50% of vegetarians is at the level of omnivores 2.5. Using data from the Food and Agriculture Organization of the United Nations on human consumption around the world, IFREMER scientists have determined the nutritional level for each food we eat.

According to a 2013 study published in the journal PNAS, humans get an average of 80 percent of their daily calories from plants and 20 percent from meat and fish. Accordingly, we humans are on an average nutritional level of 21.2, which is somewhere between anchovies and pigs. But human nutrition levels vary around the world. In Burundi, for example, plants made up 96.7% of the local diet in 2009, bringing the country’s nutritional level to 0.4. Iceland’s diet, meanwhile, consisted of about 50 percent meat that year, and they had a nutritional level of 57.2.

Of course, humans are a much bigger danger to other animals than fish and pigs. Some scientists argue that human pressure on other species makes us “superior predators.” Some researchers have coined the term to refer to the killing rate of other species by humans.

In a 2015 report in the journal Science, scientists at the University of Victoria in Canada compared the activities of human hunters and fishermen with the activities of land and sea predators. They found that humans kill adult prey 14 times more than other predators.

Bonomo said that if you consider the extent of human impact on wildlife, the figure is much higher. However, Bonomo does not agree with the assessment of humans as top hunters. (Science article authors not available for comment). In ecology, predators have a specific definition: they eat what they kill. “In most cases, we do not kill wild animals to eat them,” Bonomo said. For example, the main reasons for the declining lion population are habitat loss and conflict with humans, who do not want lions to threaten them or their livestock.

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Meanwhile, according to a 2017 study published in the journal Fish and Fisheries, people fishing in the oceans discard between 10 and 20 percent of all catches as unwanted catch. According to the US National Oceanic and Atmospheric Administration, animals that are caught unintentionally are often injured or die. “The hunter eats what he kills,” Bonomo and colleagues wrote in an unpublished response to the Science article. Instead, they coined the term “super-consumer.”

Shark

The young shark was caught as an unwanted catch and then released back into the water

Bendor et al. Reviewed studies in human physiology, genetics, archeology, and paleontology to determine the level of nutrition of human ancestors in the Pleistocene (2.2 million to 11,700 years ago). They concluded that humans had probably been hunters at the top of the food pyramid for about two million years, and that they ate mostly meat until about 12,000 years ago, when the last ice age ended.

According to a review study published in 2021 in the American Journal of Biological Anthropology, humans have more physiological similarities with carnivores than vegetarians. Some of these similarities include a very acidic stomach that breaks down complex proteins and kills harmful bacteria, and high body fat that helps carnivores starve for a while before the next big hunt.

In addition, the analysis of different nitrogen isotopes (different versions of the element nitrogen), the ratio of which usually increases with a meat-rich diet, in ancient human remains indicates high nitrogen ratios compared to the ratio of nitrogen isotopes to those in the diet. It is a plant. This analysis is another piece of evidence that shows that ancient humans ate a lot of meat.

“Several changes may have led humans to a lower level in the food chain,” Bendor et al. Wrote in their review article. According to them, the initial change was the extinction of large animals such as furry mammoths. Around the same time, humans began to develop technologies that helped them consume more plants, such as making stone tools and using them to process grain.

But even if we were once hunters at the top of the food pyramid with our meat-rich diets, it does not mean that modern humans have to climb the ladder of nutrition, Bendor told LiveScience. “This does not necessarily mean that because we were carnivores in the past, we are at the top of the food chain today,” he said. “However, our interest in meat is linked to our meat-eating past during the Pleistocene.”


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