World’s Oldest Homo sapiens Fossils Discovered

hominin skull

These images show two views of a composite reconstruction of the earliest known Homo sapiens fossils discovered in Jebel Irhoud, Morocco. (Photo credit: Philipp Gunz/Max Planck Institute for Evolutionary Anthropology)

It’s time to rewrite the textbooks. Until now, the oldest known Homo sapiens fossils, found in Omo Kibish in Ethiopia, dated to 195,000 years ago. The new fossils, discovered in Jebel Irhoud in Morocco, date to approximately 300,000 years ago. This means the new findings predate the previous oldest-known fossils by over 100,000 years.

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‘Hobbit’-sized Hominin May Be New Species

Remains of a ‘Hobbit’-sized hominin were found in a limestone cave on the Indonesian island of Flores. (Credit: Fletcher & Baylis/Photo Researchers, Inc.)

In 2003, the skull and remains of a purported ‘Hobbit’-sized human was found in Liang Bua, a limestone cave located on the Indonesian island of Flores. Controversy has surrounded the classification of the remains ever since. Recent research published in several scientific journals by anthropologists and other scientists is helping to determine where exactly the species, named Homo floresiensis, belongs in the web of life.

The remains included the skeleton of a three-foot tall adult female with a brain one-third the size of a modern human’s brain. Upon viewing the skull, some scientists initially thought it might belong to someone who suffered from microcephaly. This rare condition, caused by a double-recessive gene, is characterized by the development of a head that is smaller in circumference than normal due to improper brain development.

However, research by Dean Falk, a paleoneurologist at Florida State University, discounts this hypothesis. In her study published in the Proceedings of the National Academy of Sciences, Dr. Falk used a computer to make a model of the braincase. The model indicated that the brain had large parts of the frontal lobe and other features consistent with higher thought processes. These findings negate the idea that the individual had the underdeveloped brain of someone suffering from microcephaly.

Research by Kieran McNulty of the University of Minnesota and Karen Baab of Stony Brook University further supports Dr. Falk’s conclusion that the skull did not belong to a member of the species Homo sapiens. Together, these scientists developed a 3-D computer model of the skull and determined that the skull is not that of a modern human but that of a “scaled-down” hominin ancestor. In a study published in the Journal of Human Evolution the researchers concluded that though the structure of the skull places it in the Homo genus, it may have branched out from H. erectus or an even more ancient relative.

3-D computer models based on the skull shown here indicates that the brain of H. floresiensis had characteristics consistent with higher cognitive processes and not microcephaly. (Credit: AFP/Getty Images)

One question scientists have is how a smaller brain size with characteristics of higher cognitive thought could arise. Eleanor Weston and Adrian Lister, paleontologists at London’s Natural History Museum, studied the brain size of a dwarf species of extinct hippopotamus native to the island country of Madagascar to help answer this question. Their results, published in the journal Nature, indicate that brain size may evolve independently of body size. The researchers concluded that it is possible for dwarf mammals to evolve smaller-sized brains than would be expected compared to their mainland relatives.

Research reported in the same issue of Nature by W. L. Jungers of Stony Brook University Medical Center and several colleagues adds additional evidence that the skeleton found in the cave in Flores is not that of a modern human. Dr. Jungers’ research focused on the foot and leg bones of Homo floresiensis. Studies of the skeleton’s feet indicates that the foot bone is quite long relative to femur and tibia length. Such a characteristic has never been seen in hominin species before, although it has been observed in some species of African apes. Though other skeletal evidence points to bipedal movement, foot morphology indicates that the walking gait of Homo floresiensis was quite different from the walking gait of a modern human. This research indicates that the ancestor of Homo floresiensis may not be H. erectus but a yet-to-be-discovered primitive hominin endemic to southeastern Asia.

Though some researchers still question where Homo floresiensis belongs in the web of life, evidence continues to mount that the remains found in Indonesia belong to a species never-before seen in science. Continued research by anthropologists and other scientists will only help to further elucidate the origins and characteristics of this unusual ‘Hobbit’-sized hominin.

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