The massive mimicry of the Earth’s two million years ago provides evidence that temperatures and other planetary conditions contributed to premature human migration – and that may have contributed to the emergence of modern species about 300,000 years ago.
The findings are one of many that will emerge from the largest model to date to investigate how changes in Earth’s motion have influenced climate and human evolution. “This is another brick wall that supports the role of the climate in training human ancestors,” said Peter de Menocal, director of the Woods Hole Oceanographic Institution in Falmouth, Massachusetts.
The idea that climate change might play a significant role in human evolution has been around since the early 1920s2, when scientists began debating whether dry conditions had led the ancestors of the first humans to walk on two feet, to adapt to life in the savannah. But until now, researchers have struggled to provide conclusive evidence that climate played an important role in shaping humanity.
Orbital influence
In a recent study, Axel Timmermann, a meteorologist at Pusan National University in South Korea, and his colleagues used a computer model on a large computer for six months to reconstruct how the temperature and rainfall could have shaped what resources were available to humans in the past. a few million years. In particular, researchers have explored how long-term climate change brought about by the movement of planetary stars could create conditions conducive to human evolution.
The movement of the other planets changes the Earth’s climate by changing both the orientation of the planet and its orbit. In cycles of more than 41,000 years, the tilt of the earth fluctuates, affecting seasonal temperatures and changing the amount of rainfall in the tropics. And in the 100,000-year cycle, the Earth is moving from a more circular cycle – bringing more sunshine and longer summers – to a more elliptical cycle, which reduces sunlight and can lead to the formation of ice.
Timmermann and his colleagues used metaphors that included these astronomical changes, and then combined their findings with thousands of fossils and other archaeological evidence to determine the where and where the six species of humans were – including the first Homo erectus and modern Homo sapiens -. he lived.
Movement and mixing
The study released a confusing amount of data, and Timmermann says several interesting patterns have emerged. For example, researchers’ analysis showed that the first human species, Homo heidelbergensis, began extending its habitat about 700,000 years ago. Some scientists have speculated that this species may be responsible for the extinction of other species worldwide, including Neanderthals (Homo neanderthalensis) in Eurasia and H. sapiens somewhere in Africa.
The model suggests that the distribution of H. heidelbergensis worldwide was possible because the elliptical cycle created wet climates that allowed species to migrate widely. Imitation also showed that the habitats, in terms of climate, changed over time, and the fossil record was followed along with them. A global collection of skulls and tools is not being distributed randomly on time, ”said Timmermann. “Following a pattern” associated with climate change driven by Earth’s motion. “This is amazing to me – this is a pattern no one has ever seen before.”
One part of this pattern may provide new insights into where and how our species came from. Some genetic studies of modern hunter-gatherer groups in sub-Saharan Africa – often genetically segregated – suggest that H. sapiens is the result of a single evolutionary process in southern Africa. But other studies point to a very complex story, in which humanity began as a base for many different ancient African groups, together, transforming into modern humans.
Timmermann and his colleagues say that the reconstruction of their climate favors the idea of one-way evolution. The model suggests that our ral species originated when H. heidelbergensis in southern Africa begins to lose its habitat during an unusually warm season. This population would probably change to H. sapiens by adapting to hot, dry conditions. But these findings are unlikely to end the controversy. “Making the case that a particular weather event led to a speciation event is really difficult”, in part because of the record fossil record, “said Tyler Faith, a biologist at the University of Utah in Salt Lake City.
The same goes for many other patterns reported in the paper. “People who have lost their jobs reading this will either have a violent agreement or disagree with the proposals here,” de Menocal said. The model, however, is “an amazing achievement in itself” and “gives you an template to ask these questions”.
Most researchers say that more evidence would be needed to prove that the cycles of stars influenced the human genealogy. Faith says: “If solving the mystery of climate change and evolution were to be addressed in another paper, it would have been done 40 years ago.” That is why Timmermann and his colleagues plan to use even larger models, including the ones used. combine genetic data.
READ ALSO : Climate change is affecting biodiversity in protected areas around the world
