The mystery of the bacteria of a woman buried with honors 19,000 years ago

In 2010, a group of archaeologists found in the cave of El Mirón (Cantabria) the remains of a woman buried 19,000 years ago. This burial attracted the attention of experts because of its age, but also because the bones were covered in red paint and with pollen clumps that indicated that the tomb had been decorated with flowers. She was then christened the Red Lady. These remains have served as a sample for a new study that aimed to analyze the evolution of oral bacteria from the first hominids to modern humans. The work has discovered that there is an important difference between the set of microorganisms of the Europeans of the Upper Paleolithic (group to which the Red Lady belongs) and the humans who arrived on the continent 14,000 years ago.The bacteria of the former are very similar to those of Neanderthals, while those of the latter are more similar to those of modern man.

The set of bacteria that we have in our body is known as the microbiome. In addition to the mouth, they are present in other places, such as the nose, lungs, intestines, or skin. Although the bulk of these microbes are common to all humans and are passed from one generation to another during childhood, with breastfeeding and direct contact, there is a part that varies between each individual. Manuel González Morales, a professor at the University of Cantabria, a researcher at the Institute for Prehistoric Research in the same community and one of those responsible for the excavation of the remains of the Red Lady, defines it as “a personal trace”. “There may be specific bacteria that vary. We are never exactly identical, ”he explains. According to the calculations of the experts, in total these bacteria suppose a kilo and a half of weight.

The microbiome is a set of own and personal bacteria, present throughout our body and that we make up during childhood, with breastfeeding or direct contact.

Samples from current humans, gorillas, chimpanzees and Neanderthals have been used for the study, in addition to using other data published in previous reports. To analyze the Upper Paleolithic man, they took samples from the Red Lady and when analyzed, they found that these strains from the mouth were much more similar to samples taken in Neanderthals than those of men after 14,000 years ago, direct ancestors of the current ones. On this date a rupture is dated since, with the end of the last ice age, there is a massive migration of individuals from Asia to Europe, which ended up replacing the autochthonous population. The same thing happened with the microbiome of ancient Europeans. "The populations that colonized Europe from the Middle East about 14,000 years ago have different microbiomes than ancient Europeans,"despite the fact that they both have the same Neanderthal ancestry, ”explains González.

The authors of the study, published today in the journal

, point out that the fact that ancient Europeans and Neanderthals share a very similar microbiome is due to the fact that they inherited it from the same ancestor that existed 600,000 years ago.

At this time, researchers believe that humans incorporate starch into their diet, a compound that provides more energy than other foods and that may have helped the greater brain development of the

branch

.

"There is a separation with the rest of primates that occurs when bacteria linked to the processing of starch appear.

It is a specifically human thing, ”says González.

Mandible of the Red Lady found in the cave of El Mirón (Cantabria). Manuel Morales González / others

But this microbiome similarity only occurs in samples from Upper Paleolithic Europeans and not from individuals from Africa. “The microbiomes of the North African specimens from that time were also different. They were the microbiomes of modern men living with the microbiomes of Neanderthals, ”says González. This does not mean that the African population is more evolved than the European or Asian populations, they simply have "different evolutionary histories", according to the researcher. “Today's African populations have virtually no Neanderthal ancestry at all. The rest of the populations of Eurasia and America, which are colonized from Asia, do have a small proportion of Neanderthal lineage. Around 1-2% ”, he explains.

For Antonio Rosas, Research Professor at the CSIC, this study belongs to an increasingly important current of research, focused on the influence of microbiomes on life and biology. On a human level, Rosas considers that "knowing the evolution of this set of microorganisms helps us understand things much better from an evolutionary point of view." But this knowledge can also be applied to other animals and species. “It is important to have an independent criterion to know the evolution of animal groups. It is about studying the composition of these biomes and seeing how it changes ”, he assures. González is also optimistic about the possibilities of the study, although he considers that "it will be necessary to expand the sample to see if this discovery occurs in other Paleolithic populations."

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