May 15, 2019

Last month, on April 10, scientists announced that fossils discovered in the Philippines were evidence of a new and previously unknown variety of human that inhabited the islands some 67,000 years ago. The fossils were found at Callao Cave in northern Luzon, the main island of the Philippines. The scientists determined that the fossils represent a new species of human beings called Homo luzonensis.

Scientists found the bones of Homo luzonensis at Callao Cave on the Philippine island of Luzon. Credit: Callao Cave Archaeology Project

The fossil remains of Homo luzonensis were discovered during excavations that took place at Callao Cave from 2007 through 2015. The remains of three individuals included isolated teeth, a foot bone, two toe bones, two finger bones, and an incomplete thigh bone. Scientists observed an odd mix of anatomical features in these few remains. Some of the features are seen in modern humans alive today. Other features, such as highly curved toe bones, are seen in primitive human ancestors called Australopithecines.

These teeth of Homo luzonensis were found in Callao Cave. Credit: © Callao Cave Archaeology Project

The fossils from Luzon add to the growing list of physically distinct varieties of prehistoric humans known across the world—a list that has complicated the view of human evolution. Scientists understand from fossil evidence that physically modern human beings, Homo sapiens, first appeared in the fossil record of Africa around 200,000 years ago. Scientists believe those people eventually spread to inhabit nearly every corner of the globe. However, many regions of Africa, Asia, and Europe were already occupied by prehistoric humans when Homo sapiens arrived.

This foot bone of Homo luzonensis shows unusual curvature. Credit: © Callao Cave Archaeology Project

The Neandertals, a well known group of prehistoric humans, inhabited much of Europe and Central Asia at least 250,000 years ago. Another group, known informally as the Denisovans, is identified by genetic material recovered from a few bones discovered in Siberia (and recently, Tibet) that date to more than 50,000 years ago. Scientist do not know what the Denisovans looked like because fossil remains are so scarce, but their DNA shows they were distinct from both Neandertals and modern humans. These early people are also different from Homo naledi, a mysterious early human species first discovered at Rising Star Cave in South Africa in 2015. Even more peculiar is Homo floresiensis, a diminutive (very small) variety of prehistoric humans known from fossils discovered on the Indonesian island of Flores in 2004.

Scientist now understand that early Homo sapiens shared their world with several other physically distinct varieties of human beings. These ancient people were more like cousins than ancestors to modern humans. Today, only physically modern people remain. The discovery of yet another previously unknown human species demonstrates that prehistoric people came in many shapes and sizes.

May 11, 2017

A recent anatomical study of Homo floresiensis, a miniature ancient species of prehistoric people, strongly suggests they are not directly related to modern humans. The study, led by Australian National University school of archaeology and anthropology researcher Debbie Argue, found there was no evidence that the diminutive H. floresiensis descended from the much larger Homo erectus, a regional contemporary human species of H. floresiensis.  Many scientists believe H. erectus was a direct ancestor to later humans, including all living people today. Argue and her research team’s findings were published last month in the Journal of Human Evolution.

The skull of Homo floresiensis, at left, is much smaller than that of a modern human, shown on the right. Recent research suggests H. floresiensis is a unique species unrelated to modern humans. Credit: © AFP/Getty Images

First discovered in 2004, H. floresiensis is a species of prehistoric human that is strikingly small in stature. The species is known only from skeletal remains discovered on Indonesia’s Flores Island in Southeast Asia. The bones show that adults in this population were little more than 3 feet (90 centimeters) tall. Adults also had a brain about one-third the size of a modern human brain. The species was nicknamed “hobbits” after the short people in the fiction of English author J. R. R. Tolkien.

Previous to this most recent study, many researchers suspected that H. floresiensis descended from a group of early human beings, probably H. erectus, that had dispersed from Africa more than 1 million years ago. The scientists theorized that a group of H. erectus became isolated on remote Flores island long ago and gradually evolved (developed over time) a smaller body size. They may have died out when physically modern humans arrived on the island.

However, the new study findings show that H. floresiensis was probably descended from a far more primitive ancestor than H. erectus. The study indicates that another species of early humans, called Homo habilis, is a more likely ancestor to the Flores “hobbits.” H. habilis is the most ancient member of the genus Homo, the scientific name for the group of species that includes modern humans. H. habilis is known from fossils in Africa that date from about 2.4 million years ago to about 1.7 million years ago. Yet, to date, no fossils of H. habilis have been discovered beyond the African continent. Many scientists believe that H. habilis did not possess the intelligence or technology necessary to migrate into new environments outside of their homeland. If the hobbits of Flores Island—some 5,600 miles (9,000 kilometers) from Africa’s east coast—are indeed descendants of H. habilis, then scientists will have to reevaluate their ideas about H. habilis as they continue to study and learn about prehistoric peoples.