Surely you know any of the following names because they are classic ancestors we learned in school: Lucy, Homo habilis, Homo erectus, Neanderthals… but our history has many more players, and every so often new discoveries are made that change our lineage tree. Find out in this article the latest findings your teachers could not explain to you .
HOMO NALEDI
It is almost forced to start with one of the latest discoveries that is encouraging discussions in paleoanthropology to gain a key position in our family tree. The discovery of a new species, Homo naledi, was published the September 10, 2015 by Lee Berger et al. It was discovered in a cave system in South Africa named Rising Star at the Dinaledi chamber (“Naledi” means “star” in the local language, Sesotho). It is especially interesting for several reasons:
- At the moment in the site have been found more than 1,700 human fossils accumulated, making it the largest of South Africa, behind the famous Sima de los Huesos (“Pit of Bones”, Atapuerca, Spain), the largest of the world, with more than 6,000 fossils.
- The cave is very difficult to access, with corridors of only 19 cm wide, so it was a selected team of 6 thin paleoantropologysts (all women) that reached them.
- The bones belonged to 15 individuals of all ages, male and female, so we can get extensive information about the new species. Some were even on the floor of the cave without mineralize.
- The physical characteristics of H. naledi are a mix of Homo traits (height, feet) and Australopithecus (shoulders, chest, pelvis), the genus from which most scientists believe Homo appears about 2.8 to 2, 5 million years ago. This may suggest that H. naledi could be the first Homo, the missing link between Australopithecus and us.
Some of the impressive number of bones discovered Homo naledi. Photo by John Hawks - The most intriguing of this discovery, it is believed that the bones were placed there deliberately. By geography, access to the cave was the same as today, they could not fall into the pit, the bones could not be brought by a water flooding or any animal, they have no marks of violence … It could be a funeral ritual? So far, the first rites are attributed to H. neanderthalensis, with most modern physical characteristics and a large cranial capacity compared to H. naledi (1.475 cm3 versus 560 cm3 at the most).
The oldest known Homo fossil, 2.8 million years old, corresponds to a jaw found in Afar in March 2015 which has not been associated to any species. Was H. naledi the first Homo? Is it really an ancient species? Is it possible they had self-awareness so early and cared for their dead? Unfortunately, researchers have not been able to date the remains yet, so many questions remain unanswered and we will must wait for future interpretations of one of the most important discoveries of recent times.
THE DENISOVANS
In Denisova Cave (Siberia) in 2008 was found a non-spectacular fossil: a piece of a finger bone that was dated 30,000 years old and attributed to an individual of about 8 years which turned out to be a gir. But when DNA was extracted, it was concluded that belonged neither to H. sapiens or H. neanderthalensis, but to a new species. Later two teeth of another individual of the same population were found. In the same cave also Sapiens and Neanderthal remains were found.
Is it possible that Denisovans hybridized with Sapiens? DNA studies in the current populations indicate that 5% of DNA aboriginal Australians, Papuans and other peoples of Melanesia is Denisovan. On the other hand we know that 20% of the DNA of accumulated European populations is Neanderthal.
WHERE DO WE LOCATE THEM IN OUR FAMILY TREE?
It is thought that Neanderthals and Denisovans had a common ancestor (H. heidelbergensis), who emigrated to western Europe and Central Asia evolving to H. neanderthalensis, who subsequently hybridized with us, and from Southeast Asia where would evolve in the hominin Denisova, who also hybridized with H. sapiens. This would explain the presence of DNA in the current populations of Australasia.
HOW THEY WERE LIKE?
The absence of more fossils or traces of objects and tools prevent us to know how they looked like and what were their skills. Nor it has been found explanation for the lack of Denisovan DNA in the Russian or Chinese populations, so close geographically to the Denisova cave. Denisovans remain a mystery to science.
THE FLORES WOMAN
Homo floresiensis, as its name indicates, lived on the island of Flores (Indonesia) only between 95,000 and 12,000 years ago. It was discovered 12 years ago. It is the only site where this species is found.
As in previous fossils, the mix of features caught the attention of the scientific community, especially for its small cranial capacity and height, earning them the nickname hobbit. First they thought it was an individual with a pathology, or a pygmy of a known species, as their morphology was very strange in a so modern fossil. But now we have remains of at least 12 individuals with the same traits, so we can talk (for the moment) of another species.
HOW THEY WERE LIKE?
- Small height: the most complete skeleton belongs to a female only one meter tall and 25 kg weight.
- Small skull: their cranial capacity (380-420 cm3) was similar to the current Australopithecus or a current chimpanzee, but the brain had a more similar Homo anatomy. The teeth were large relative to the skull.
- Long feet and short legs: feet were very long in relation to the legs, which were short and stout. This and more features suggest that locomotion was different from ours and were bad runners.
- Long arms: besides a proportion nearest to Australopithecus and H. habilis than H. sapiens, arms were robust and had a powerful musculature.
- Stone tools and fire: besides the existence of tools of earlier hominans found in the cave, some tools have been associated to H. floresiensis with a technology similar to the Oldowan Industry, the first to be invented. Also they dominated the fire.
WHY THEY WERE SO SMALL?
Controversy continues: was a direct descendant of Australopithecus (how could they have traveled so far from Africa?), or a recent member of our family tree so small due to lack of resources?
The insular dwarfism is an evolutionary process due to a long-term isolation in a small area with limited resources and lack of predators. Flores pygmy elephants (Stegodon) hunted by H. floresiensis with this adaptation were also found. The opposite process it is the island gigantism, in which animals that are usually small on the continent are giants in the islands, such as the Galapagos turtles and the extinct lizards or rats of Flores.
H. floresiensis may be the result of this dwarfism, and some scientists believe it could actually be a reduced Homo erectus. The majority opinion today is that they were already so small when they reached Flores (such as the Australopithecus from whom evolved), and modern features are due to convergent evolution with H. sapiens. Unfortunately it has not been able to extract DNA in good condition to put them in the phylogenetic tree for sure.
How did they get to Flores? They had a language, art and cultural expressions? Did they get in contact with our species? They were extinct due to a volcanic eruption? Who made the other ancient tools previous to H. floresiensis? The debate and the unknowns remain open.
REFERENCES
- Roberts, Alice. 2012. Akal. Evolución: historia de la humanidad.
- This Face Changes the Human Story. But How?
- Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa
- New Homo species found
- Homo Naledi: New Limb Added To Human Family Tree
- Homo naledi: una nueva especie humana descubierta en Sudáfrica
- Hallada en África una gran sima de huesos con una nueva especie humana
- El caso del ancestro perdido
- Los denisovanos, una humanidad perdida
- Human evolution: Small remains still pose big problems
- El “Hobbit” (Homo floresiensis), era la versión mini del erectus debido al enanismo insular
- Homo floresiensis (Smithsonian)
- Vuelve el Hobbit
- Foto de portada de National Geographic
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