A recent discovery of fossil bones belonging to the first hominids suggests that some animals hibernated during extreme cold. In fact, scientists have seen many clues on these human remains, which are usually similar to fossils of hibernating animals. Thus, our ancestors were probably able to slow down their metabolism and fall into deep sleep for several months …
These fossil bones were discovered at the site Chain of bones, Near Burgos in the north of Spain. This ancient mass grave, fifteen meters deep, known as the Paleontologists, contains deposits of about 430,000 years old fossils. The site is one of the two largest deposits of human fossils (the other being in South Africa). Thus, in recent decades, excavations have brought to light the remains of many humans, perhaps the first Neanderthals or their ancestors.
Research conducted on this site has already provided much information on the development of hominids in Europe. Today, paleoanthropologists Juan-Luis Arsuga and Antonis Bartisokas, report in the journal anthropologyThe discovery of new particularly intriguing clues: These suggest that the metabolism of earlier men was varied with the seasons, allowing them to survive the cold period.
Symptoms of bone growth disruption
Hibernation refers to a condition in which some animals immerse themselves, slowing their metabolism to very low levels; They reduce their body temperature and breathing rate, and draw energy from stored fat stores for the rest of the year. This strategy of adaptation to cold is particularly adopted by marmots, dormis, hedgehogs, and even bats. Until now, it was not suspected that humans could alter their metabolism in this way for several weeks.
However, Arsuga and Bartisokas claim that fossils found in the Sima de los Housos pit – particularly those of juvenile individuals – show seasonal variations, suggesting that bone development had been disrupted for several months each year. Two paleoanthropologists believe that the first humans voluntarily came to a slow metabolic state to survive the ice age, when food was scarce. These stages of hibernation were actually recorded as disturbances in their bone development.
Researchers believe the hypothesis may be difficult to visualize. They point out, however, that many mammals engage in hibernation, including primates such as galagos and lemurs. There is reason enough to think that this ability can be found in humans as well: ” The genetic basis and physiology of such hypometabolism can be preserved in many species of mammals, including humans. ”, Explain two experts. They also point out that the remains of a hibernating cave bear were also found at the scene, which makes it more reliable, they say, that humans have done.
The remains of human bones provide uneven evidence: they show lesions similar to those seen on the bones of hibernating mammals. More precisely, many of these lesions are pathognomonic and show that these hominids were affected each year by osteomalacia (bone loss), secondary hyperparathyroidism (overgrowth of parathyroid hormone due to increased plasma calcium levels) and osteostrophy. Kidney (complication of kidney failure). According to the researchers, these disorders are persistent for all hibernation; This strategy would have been their only solution to survive in the cold conditions.
Deep sleep or simple torture?
Two paleoanthropologists nonetheless examined several countermeasures to test the validity of their hypothesis. For starters, modern Inuit and Sami do not hibernate, although these people live in equally difficult climatic conditions. So we can ask ourselves why would the first men have hibernated? Arsuga and Bartisokas point out that the difference is only substantial in food resources: Inuit and Sami can feed oily fish and reindeer even during winter, so they are not forced to hibernate.
One and a half million years ago, the area around the site of Sima de los Hussos, on the other hand, could not meet the needs of the population: ” L’aridification dELIBErie, At that time, sufficiently high-fat food could not be made available to the people of Sima during the harsh winter, which forced him to resort to hibernation “, Explain to the researchers. However, other experts believe that debate on this topic is ongoing and more research will be needed before claiming that the first hominids went into hibernation. ” There are other explanations for the variation in bones found in the Sima Pit and these need to be fully addressed before coming to any realistic conclusions. Said Patrick Randolph-Quinney, forensic anthropologist at the University of Northumbria in Newcastle.
In addition, Chris Stringer of the Museum of Natural History of London recalls that large mammals such as bears are not actually hibernated: although their heart rate slows, their large bodies cannot adequately lower their core temperature And it remains relatively stable. Thus, they go into very shallow sleep, a type of drowsiness, known as torum or overwintering; The bear is also called a semi-hibernator (as are badgers, raccoons, and constipated).
In a situation like this, the energy needs of the human mind of the people of Sima remain very high, which endangers the survival of individuals. Stringer believes the mark is worthy of detection: ” This idea is attractive and can be tested by examining the genomes of individuals from Sima, Neanderthal, and Denisovans for indications of genetic changes related to the physiology of torma. », He concludes.