Has the diet made a human out of a mouse?

Scientists at the Max Planck Institute for Evolutionary Anthropology (Leipzig, Germany) demonstrated on a mouse model that some differences between humans and monkeys are due to differences in diet.

The diets of humans and monkeys differ significantly. Not only do we eat more meat and fat, but we also prefer to cook. There is a hypothesis that addiction to this type of diet played a key role in human evolution. However, until recently, the effect of diet on the physiological and genetic differences between humans and monkeys has not been studied.

The authors were able to reconstruct some of these differences in experiments on mice that were kept on three different diets for two weeks: raw vegetables and fruits that make up the diet of chimpanzees living in the zoo, food from the university cafeteria and food from McDonald's (the latter led to rapid weight gain). The effects of the monkey diet on the liver of mice differed significantly from the effects of eating human food. This was expressed by thousands of differences in gene expression in liver cells. No differences in gene expression in brain cells were observed. A significant part of the diet-related differences in the levels of gene expression in the liver was observed earlier when studying the differences between chimpanzees and humans. This indicates that it is the consumption of different foods that underlies these differences.

Moreover, apparently, the genes associated with the diet change faster than all the others: during the experiment, the expression of their protein and promoter sequences changed faster than the authors expected – possibly as a result of adaptation to new types of diet.

Please note: the expression, i.e. the activity of genes, changed, but in no way their structure or the composition of chromosomes. And there is no Lamarckism: if a hundred generations of mice are kept on chips and hamburgers (and not in greenhouse laboratories, but in conditions, in everything else, except nutrition, close to natural), then maybe selection will eventually lead to the appearance of a breed of mice that will stop eating normal mouse food. With aphids adapted to feed only on the juice of a strictly defined plant (stenophages), such experiments were conducted. After several years of torment and mass death, the surviving insects became stenophages in relation to a previously unsuitable type of food. And, as it was established quite recently, humans differ from chimpanzees not only (and perhaps not so much) by the presence or absence and change in the structure of genes, but also by the level of expression – protein synthesis – of many of the same or not fundamentally different genes.

There is no doubt that the change in diet influenced human evolution. As it happened millions and hundreds of thousands of years ago, it is unlikely to be possible to restore, but the transition from hunting and gathering to agriculture and a predominantly grain diet among sedentary tribes, to a predominantly meat diet among hunting peoples, etc. was certainly accompanied by the predominant survival of those whose biochemistry was better adapted to the new composition of nutrition. Our latest achievement in this field is lactose tolerance by adults, acquired by Europeans and African pastoral tribes just yesterday – about 5,000 years ago.

And what is the point in studying changes in gene expression in grain–eating mice under the influence of monkey and human, as well as non–human - from McDonald's - diets, ask Somel M and other authors of the article Human and Chimpanzee Gene Expression Differences Replicated in Mice Fed Different Diets published in PLoS One.

Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of ScienceDaily

05.02.2008