This article is from WeChat official account: science home (ID: steamforkids) , Author: Seven Jun
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Eating only one food a day is definitely not good for your health. If a group of animals can only eat one type of food in their lifetime, what will happen to them?
There is a kind of cute little animals, because human relations can only live on one kind of food, and a single food makes them lose their motherhood and swallow their own babies.
And in July of this year, the International Union for Conservation of Nature (IUCN) listed this animal as critically endangered and predicted them Will be extinct in 30 years.
Cricetus cricetus European Hamster Picture source: Mathilde Tissier
This animal is a cute European hamster (Cricetus cricetus). There are 26 species of hamsters in Eurasia. Among them, European hamsters are more fierce. They don’t like to be slapped by people, but they look really cute.
Will rodents as strong as Xiaoqiang go extinct? This is really hard to imagine. After all, European hamsters were once all over Europe and West Asia, so they were also called ordinary hamsters (the common hamster). But after the start of human agricultural industrialization, European hamsters began to become rare.
Since the 1960s, scientists have noticed that the number of European hamsters has begun to decrease dramatically. From 1972 to the present, the distribution range of French European hamsters has decreased by 94%, and they are now almost exclusively found in the Alsace region in northeastern France; in Germany their distribution range has dropped by at least one third, and in Eastern Europe by more than 75%.
The former distribution of European hamsters Picture source: wikipedia
You may wonder, can’t rodents give birth to thieves?
Yes, like many rodents, European hamsters also have a rapid rate of generational change. Their gestation period is only 18 days. However, in the last 100 years, the reproduction rate and lifespan of European hamsters have decreased significantly.
In the early 20th century, the life span of European hamsters was 4 years, but now it is only 2 years. For most of the 20th century, female European hamsters can give birth to 20 cubs a year. But now this number has dropped to 5-6.
IUCN pointed out that the decline in the number of European hamsters is mainly due to low reproduction rates. Historically, there have been many cases of rapid extinction of once a large number of wild animals. For example, the North American passenger pigeons, once the most common bird in the world and numbered more than 5 billion in the United States, became extinct within 100 years, and the reason for their extinction was also due to low reproduction rates.
North American passenger pigeon
Therefore, IUCN recently issued a warning that if no action is taken, European hamsters will become extinct within 30 years.
But wait, rodents eat human food, why should we protect them?
Although rodents often give people the impression of harmful organisms, in fact European hamsters have important ecological functions.They are key species( keystone species), is the food of many important predators, such as eagle owl (Bubo bubo).
Eagle Owl Picture source: wikipedia
After realizing this, many European countries have started European hamster conservation programs, including France, Germany, Belgium, Poland, Ukraine and other countries, but these programs have little effect.
Mikhail Rusin, a member of the IUCN Small Mammal Research Group, said: “Although there are plans for the conservation and reintroduction of European hamsters in some areas, the decline in their numbers has not been curbed.”
Gerard Baumgart, director of the Alsace Environmental Research Center in France, said: “Something must be out of balance.”
Academic circles now have different reasons for the endangerment of European hamsters. It is generally believed that this is related to human activities, pesticides and plowing, climate warming, and light pollution. But recently, some scientists have discovered through experiments that a single crop grown by humans has a devastating blow to the reproduction of European hamsters.
Caroline Habould, a physiologist at the University of Strasbourg in France, noticed that the same change in the number of hamsters is the increase in the unity of local crops. In the past 100 years, French farmers have begun to grow corn on a large scale. crop.
In Alsace, France, 55%-80% of the cultivated land is grown with corn. In Germany, the situation is better, about 12% to 19% of the arable land is grown with corn.
Before humans planted single crops, local hamsters ate the rhizomes of various plants and insects. But now the living environment of European hamsters is like this–
A cornfield somewhere in France. Photo source: Stephane Mahe/REUTERS
Some studies have found that when the proportion of corn exceeds 18%, European hamsters will not appear.
In order to study whether the number of hamsters has dropped sharply because they often eat the same crop, Habould and his colleagues conducted a series of studies and published them in Proceedings of the Royal Society B in 2017.
They tested 4 different recipes for European hamsters: some hamsters were fed a mixed meal of wheat + alfalfa/earthworms, and some ate a mixed meal of corn + alfalfa/earthworms. As a result, no matter whether the food is wheat or corn, there is no difference in the number of pups born to European hamsters, but these two foods have a great impact on the survival of the pups.
First of all, although corn and wheat have similar energy content, the weight of the pups in the corn group is 45% lower than that in the wheat group, and the survival rate is 75% lower.
Of those hamster pups whose mothers ate wheat, about four-fifths were successfully weaned, but only 5% of the pups in the corn group were weaned.
Successful weaning means that the pups survived to weaning. The pups in the corn group actually died before drinking the mother’s milk. The cause of death of the pups in the corn group also shocked the researchers: The hamsters in the corn group were completely non-maternal. Not only did they not give birth in the nest like normal hamsters, but they also gave birth to the pups on the first day after delivery. class=”text-remarks” label=”Remark”>(The cubs are still alive) are stacked with food, and then eaten.
Generally speaking, hamsters only eat their pups when they feel threatened or lack of food, but the behavior of preparing to eat after birth like this is really abnormal.
In this study, only one corn-eating hamster did not eat the offspring, but her offspring began to kill each other when they were 34 days old, and two males ate their sisters.
Actually, the abnormal behavior of corn-based hamsters is manifested as early as when they mate: they are grumpy and irritable, and are very sensitive to sounds in the room.
Why do hamsters that eat corn lack maternal love? Could it be corn that affected the secretion of the hormone of love?
To verify this, the researchers also measured the level of the love hormone oxytocin in the hamsters before and after giving birth.
The strange thing is,The levels of oxytocin in hamsters whose motherhood was lost were not lower than those in the wheat group. In other words, mother hamsters eat children not because of their hormone disorders.
These researchers believe that hamster mothers should have this series of abnormalities due to insufficient nutrition caused by a single food. So, what nutrients do these hamsters lack if they only eat corn?
Researchers believe that the symptoms of corn group hamsters suggest that they lack a trace element-vitamin B3(niacin).
In the liver, vitamin B3 is converted into the coenzyme NAD(nicotinamide adenine dinucleotide) which transfers protons. NAD is involved in more than 400 biochemical reactions. Therefore, the lack of vitamin B3 will affect a series of normal physiological functions including metabolism, reproduction, and nervous system.
Vitamin B3 can be obtained directly from food or synthesized from tryptophan. Of course, tryptophan is also derived from food and cannot be synthesized by the human body. And because the human body and hamsters cannot synthesize vitamin B3 or tryptophan, it must be taken from the diet.
Foods rich in vitamin B3. Corn needs to be treated with alkaline water to effectively release vitamin B3. Image source: Africa Studio
Actually, corn itself contains a lot of vitamin B3, but the vitamin B3 in corn combines with sugars and glycopeptides to form a complex, which is difficult to be directly ingested and utilized by the body.
To release the vitamin B3 of corn, it is necessary to cook with alkaline water(nixtamalization), that is, boil corn with lime water. The main component of lime water is calcium hydroxide, which can release the vitamin B3 bound in corn.< /p>
Alkaline water cooking method
This method was first discovered in Mexico where corn is a staple food, so people in Mexico are not deficient in vitamin B3. But after the corn was spread to Europe and other regions, the locals did not know the correct cooking method for this imported product, so they paid a heavy price.
Lime-boiled corn (right) and corn without lime-water treatment (left). Image source: wikipedia
During the two hundred years from the 18th century to the middle of the 20th century, 3 million people in North America and Europe died from pellagra caused by vitamin B3 deficiency.
We have encountered this term in middle school textbooks, but many people do not understand the lethality of pellagra. The main manifestations of pellagra are 3D: dermatitis (dermatitis), diarrhea ( diarrhea) and dementia (dementia), together are called 3D. Coupled with death (death), it is 4D.
The skin of a patient with rough skin. In fact, the legend that “vampires” are afraid of light may come from the symptoms of dermatitis in patients with rough skin.
Pellagra was first discovered by Catalan doctor Gasper Casal in 1762. At that time, Casal noticed that the hands and feet of the farmers in Asturias, Spain, had red, swollen and rough skin, and the main food for these poor people was corn.
In 1895, Moritz Kaposi, a Hungarian doctor, discovered that pellagra is a regional disease, which mainly occurs in the poor in the Lombardy Plain, Venice and Southern France. The main food of the middle and lower classes in these areas is corn. . Pellagra was also found in the southern United States in 1902.
In Europe and the United States, pellagra has been prevalent among farmers who eat corn as a staple food for two hundred years. In 1914, it was finally discovered that pellagra was related to the lack of a certain nutrient, and it was noticed that pellagra and “black tongue” in dogs were the same type of disease. Finally, in 1922, vitamin B3 was discovered to be a nutrient that can prevent and treat pellagra.
After the modernization of agriculture, is pellagra a long way from the lives of ordinary people? Not really.
In the refining process of wheat and corn, although calories will not be lost, important nutrients such as vitamin B3 will be lost. Therefore, before the discovery of vitamin B3, there were still 100,000 deaths from pellagra in the southern United States. Pellagra is also considered to be the most serious disease caused by nutritional deficiencies in the history of the United States.
at 20In the 1930s and 1940s, American researchers discovered the association between vitamin deficiency and some diseases. Therefore, in 1942, the predecessor of the US Food and Drug Administration (FDA) was the Food and Nutrition Commission (the Committee on Food and Nutrition) recommends that manufacturers add vitamin B1, B2, B3 and other essential nutrients to the flour. In the few years after the implementation of this measure, the death rate caused by pellagra in some states in the United States has dropped to one-tenth of the original rate.
It should be noted that lack of vitamin B3 can not only cause pellagra, but also mental illnesses such as depression and delirium. Sixty years ago, Canadian biochemist Abram Hoffer noticed that schizophrenia patients experienced relief after taking high doses of vitamin B3.
Some scholars even suggested that improperly cooked corn may lead to violent acts such as murder. A study published in the Journal of Orthomolecular Psychiatry in 1978 pointed out that countries with high corn consumption also have a higher crime rate for homicides, which may be caused by tryptophan and/or Triggered by serotonin deficiency.
Habould believes that the cannibalistic behavior of hamsters in the corn group is very similar to the behavior of humans whose main food is corn.
The physical condition of the hamsters in the corn group suggests this: their tongues are swollen and dark in color, and their blood is very viscous, and it is difficult for researchers to draw blood. These symptoms are similar to black tongue in dogs.
In order to confirm the link between vitamin B3 deficiency and abnormal hamster behavior, they supplemented the corn group with vitamin B3 and then observed the changes in the hamsters.
Unsurprisingly, after supplementing 0.3 mg of vitamin B3 a day, the motherhood of hamsters returned, and the female rats began to raise offspring like normal hamsters.
But the hamsters in the field are not so lucky. The consequences of eating only corn are really chilling.
This article is from WeChat official account:, Author: Seven Jun