People are very big heads. Not only in a figurative sense, but also in the strictly physical. We have the head we have for what … That goes in, a disproportionate brain. It is estimated that it is seven times larger than the person who would have a different mammal with the same body weight and three times more extensive than that of a different primacy. In addition to great, the other more striking function is energy -avidity. With only 2% of the body’s weight – no more than one kilo -, it monopolizes up to 20% of the energy that we consume.
Feeding this fantastic machine was a challenge from an evolutionary point of view. There are various theories that try to explain. The most common suggestion suggests to solve this big problem was to make our carnivores. The length of the digestive tract depends on the food it processes. In the case of herbivores it is longer to extract all possible juice in the vegetables that they consume; In the case of carnivores, shorter because meat, proteins, is easier to assimilated. In other words, because you do not arrive, we bet on the brain at the expense of the digestive system.
This was accompanied by cooking. Passing food through fire includes making all its nutrients, while if we eat them raw, we only ‘stay’ between 30 and 40% of the properties. All this happened about 1.8 million years ago and multiplied our brain masses by three.
Change in metabolism
Another hypothesis ensures that our brain masses grew to enable our ancestors to better develop in a life in an increasingly complex society. And a third indicates ecology. These same ancestors, who lived from hunting and gathering in the African Savannah, had to look for life to find both food and to save and process it. According to the latter explanation, the inhospitable the drug that surrounds us and the more we must continue to learn to overcome the obstacles that it imposes after childhood, the more stimulus for the brain to grow.
Now a study by American University of Northwestern points to another ‘culprit’ in that evolutionary jump: the intestinal microbiota, the millions and millions of microbes who live in our intestines and that help us to break down food and produce energy. “Our findings establish a causal role of the intestinal microbiota in the differences in metabolism and suggest that it may have been an important facilitator of metabolic changes during human evolution that supported the encefaling,” show the authors of the research.
The scientists implemented microbes – mice of two types of primates of large brains – ours and those of the squirrels, an animal of 30 centimeters and half a kilo of weight that lives in South America – and a kind of relatively small brain primates – the Makaken – and measures the changes in the physiology of the heads. The percentage of fat, glucose values and functioning of their livers was mainly adjusted in itself. The result is that the rodents of the first group produced and used more energy, a surplus that they used to produce glucose – Blood -sugar – what exactly is what the brain feeds. For their part, that of the second group tended to collect fat.
Moreover, they saw another striking result. Mice with microbes of species with large brains showed “biological similarities”, although we are not close relatives of the squirrel monkeys. How to explain it? “These findings suggest that when people and squirrel monkeys developed separately, their microbial communities have changed in the same way to offer the necessary energy,” they emphasize.
Although confirming whether our ‘Bichitos’ were so important in the growth of our brains, there is no doubt about their interest in health. It is known that when they are in good condition, they help us defend ourselves against infections, they are fundamentally in neurological development and even change the mood. Know that between 90 and 95% of serotonin, the neurotransmitter associated with emotions, takes place in our ‘intestines’. When it is imbalance, it is linked to diseases such as Alzheimer’s and Parkinson’s.
