The cave of Callao, in the Philippines, is a huge cavity with seven chambers, but the most interesting is very close to the entrance. There have been unearthed 13 bones and teeth that, according to its discoverers, belong to a new member of our own gender to which they have baptized Homo Luzonensis and that he lived at least 67,000 years ago on the island of Luzon.
The finding obliges to change textbooks - again - because the list of members of the genre Homo that inhabited the Earth in this period passes of the five known ones (Neanderthals, Denisovans, Hobbits de Flores, erectus Y sapiens), To six.
All these hominins are a motley family of primates linked by more recent kinship ties than with other living hominids, such as chimpanzees or bonobos. Each one represented a more or less successful evolutionary experiment. All have become extinct except one, the Homo sapiens, who every time he finds a new relative asks why they disappeared and we do not.
The human of Luzón is an enigma. It is impossible to know what his face was like, because there are no skull fragments, nor what height he had, because the only available bone that could carve him, the femur of a thigh, is broken. The remains found, the first a phalanx found in 2007 that dates back 67,000 years, and the rest found between 2011 and 2015 with an age of at least 50,000 years, belonged to two adults and one child. Their teeth, two premolars and three molars, are very small, similar to those of a current human or those of the Homo floresiensis, the one-meter-tall, chimpanzee Asian hominino who lived on the Indonesian island of Flores at the same time. In contrast, the bones of the hands and feet are much more primitive, comparable to those of the australopithecines that lived in Africa two million years before and whose limbs were adapted to live hanging from trees.
"If you look at each of these traits separately you will find them in one or another species of Homo, but if you take the complete package there is nothing similar, so this is a new species," explains Florent Détroit, paleoanthropologist at the National Museum of History. Natural of Paris and co-author of the study that describes the new species, posted today by the scientific journal Nature. It has been impossible to extract DNA from the remains, which increases the mystery about its origin.
"This finding will generate a huge debate," says the CSIC paleoanthropologist Antonio Rosas. "It is not easy to evaluate it because there are very few fossils, but there is a basis to propose that it be a new species. What is clear is that it confirms that the diversity of our genre is incredible and is in the antithesis of that linear model that represents one species of primate after another until culminating in the sapiens"He says. For Rosas the most important thing is that this species shows an alternative way of evolution to our characterized by isolation.
Luzon has been surrounded by the sea for two and a half million years. The human found in the Callao cave had to cross it, nobody knows how. It's the same thing that the Flores man did to get to his own island, where he made stone tools as sophisticated as those of the sapiens. In Cagayan, a valley near the Philippine cave, stone tools have been found that reveal the presence of hominins at least 700,000 years ago, so it is possible that they were luzonensis. It is at this point that at least three different possibilities open up about its origin.
The most plausible is that this species descends from Homo erectus, the first hominin who left Africa and populated Asia 1.8 million years ago. All current humans come from another wave of Homo sapiens very later that they left Africa about 70,000 years ago.
The luzonensis would be a descendant of the erectus who came to what is now China. Like its congener of Flowers, it would have evolved for tens of thousands of years isolated with the evolutionary pressures that this implies, which possibly transformed it into a human of dimensions smaller than its ancestors. This possibility is supported by the size of the teeth and also that of the metatarsal of the hand, whose dimensions coincide with those of the Negritos, explains Détroit, current humans living in the Philippines, Malaysia and the Andaman Islands who do not usually exceed the meter and half of height. This is a disturbing fact if other recent evidence is added: the Jarawa of Andaman have 1% of DNA from another species of Homo unidentified, fruit of a crossing thousands of years ago.
The second option is that luzonensis comes from a surge that came out of Africa before erectus, possibly of australopithecines. There are no fossils to support this hypothesis, but it can be argued by the morphology frankensteiniana of the luzonensis. A third option, defended by Chris Stringer, a researcher at the Natural History Museum in London, is that Homo of Luzon and Flores descend from a local common ancestor that emerged on the island of Sulawesi, where stone tools of about 110,000 years have been found.
The controversial American paleoanthropologist Erik Trinkaus believes that none of the options is plausible and ensures that luzonensis he was a sick individual, the same as he was said in his day of Flores's hobbit. "It is a rarity that should be considered in the context of the Pleistocene, in which malformations were very abundant," he explains. It may not be something so crazy given the new paradigm revealed by genetics in which Neandertals, sapiens and denisovanos crossed and had fertile children. "The debate is too polarized, I do not think the Homo floresiensis Be a Homo sapiens pathological, but it does have pathologies, something that is not surprising if you are talking about an isolated population, with high levels of inbreeding and that also suffers a process of insular dwarfism that affects processes of general growth, especially when it has been seen that hybrids between species produce pathologies, "says María Martinón, director of the National Research Center on Human Evolution.
The hobbits of Flores disappeared 50,000 years ago, just when the Homo sapiens He arrived in Asia. The majority of the bone remains of luzonensis have just that minimum age, which opens a final mystery about whether the sapiens they had something to do with the disappearance of these two distant relatives who are no longer here to explain their history.