Nav: Home

Dental study of juvenile archaic Homo< fossil gives clues about human development

January 16, 2019

Most aspects of dental development for a juvenile Homo specimen from the Pleistocene fall within the modern human range, according to research by a group of Chinese and international scientists. The study was recently published in Science Advances.

The results are useful in helping to identify when modern human-like growth and development first appeared.

The research was conducted by XING Song from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences in collaboration with colleagues from France, the U.S., Spain and South Africa. The scientists used advanced synchrotron microtomography to analyze a juvenile Homo dental fossil from the Middle-Late Pleistocene transition. The fossil is estimated to be ~104,000-248,000 years old, based on different dating techniques.

Compared to other primates, modern humans take a long time to develop physiologically, which is associated with characteristics including prolonged childhood dependency, delayed age at first reproduction and long lifespan. Overall, modern humans "live slow and die old." Understanding when and in which earlier hominins modern human-like growth and development (or life history) first appeared is a subject of ongoing investigation and of strong interest.

Teeth, one of the most abundant materials within fossil collections, are irreplaceable in tracing human life history due to their special features. First of all, their growth is rhythmic and recorded as daily (short-period) as well as longer-period incremental lines in hard tissues that can be imaged non-destructively, thus preserving precious fossils. Secondly, several dental developmental traits (e.g., prolonged crown formation times and delayed molar eruption ages) are typical of modern humans and associated with their prolonged life histories.

According to previous studies, earlier hominins were quite variable in their developmental rates. However, none of them displayed the prolonged periods of dental growth and development that characterize modern humans.

H. erectus also had an accelerated pace of dental growth. Some aspects of Neanderthal dental development appear to be encompassed within the modern human range of variation, although these aspects generally fall at the advanced end of that range. What was archaic Homo (sometimes referred to as archaic H. sapiens) like in terms of dental development? Archaic H. sapiens was proposed to be a transitional form connecting H. erectus and modern humans.

Northern China's Xujiayao site fortunately produced a juvenile maxilla of archaic Homo that could help answer this question. At death, the child's first molars had only recently erupted; incisors, canines, premolars and second molars were still buried inside the jaw.

A direct U-series dating of associated mammal teeth suggests that the juvenile hominin lived 104,000-years ago. However, the deposits containing the Xujiayao fossils date to 148,000-248,000 years before present (B.P.), based on optically stimulated luminescence (OSL). This range corresponds to the transition from the Middle Pleistocene to the Late Pleistocene, a very critical time for the origin of H. sapiens.

At the Xujiayao site, three systematic excavations were carried out in the 1970s and 20 hominin fossils were unearthed, including cranial and mandibular fragments as well as isolated teeth. The juvenile maxilla, numbered "Xujiayao 1" among the hominin fossils, was recovered in 1976. A series of comprehensive studies performed in the past few years on the Xujiayao hominin fossils have consistently revealed a complex mosaic of morphologies, including characteristics found in H. erectus, modern humans and Neanderthals.

To assess various features of dental growth and development, the permanent teeth of the Xujiayao juvenile were scanned at the European Synchrotron Radiation Facility (ESRF) in France by Paul Tafforeau. With this high-resolution and non-destructive virtual histology, researchers were able to trace the short-period and long-period incremental lines without physically sectioning the valuable fossil teeth.

Through systematic counting, cross-matching and calculation, the initiation time, crown and root formation time, first molar eruption time and age at death were obtained with high certainty.

After comparing these developmental variables with those of extinct and extant human samples, most aspects of the Xujiayao teeth were found to fall within the range of variation of modern humans, except for a relatively fast average extension rate of the roots.

In particular, the Xujiayao juvenile has a prolonged crown formation time, delayed first molar eruption time, and more perikymata within the cervical half of the crown.

This work is the first systematic assessment of dental growth and development in an archaic Hominin (genus, Homo) from East Asia. Its findings suggest that a slow life history comparable to that of modern humans might have appeared prior to fully modern human morphology.

Chinese Academy of Sciences Headquarters

Related Fossil Articles:

Rare lizard fossil preserved in amber
The tiny forefoot of a lizard of the genus Anolis was trapped in amber about 15 to 20 million years ago.
Reconstructing the diet of fossil vertebrates
Paleodietary studies of the fossil record are impeded by a lack of reliable and unequivocal tracers.
Fossil is the oldest-known scorpion
Scientists studying fossils collected 35 years ago have identified them as the oldest-known scorpion species, a prehistoric animal from about 437 million years ago.
Fossil fish gives new insights into the evolution
An international research team led by Giuseppe Marramà from the Institute of Paleontology of the University of Vienna discovered a new and well-preserved fossil stingray with an exceptional anatomy, which greatly differs from living species.
What color were fossil animals?
Dr. Michael Pittman of the Vertebrate Palaeontology Laboratory, Department of Earth Sciences, The University of Hong Kong led an international study with his PhD student Mr.
New Cretaceous fossil sheds light on avian reproduction
A team of scientists led by Alida Bailleul and Jingmai O'Connor from the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences reported the first fossil bird ever found with an egg preserved inside its body.
Fossil deposit is much richer than expected
Near the Dutch town of Winterswijk is an Eldorado for fossil lovers.
Researchers add surprising finds to the fossil record
A newly discovered fossil suggests that large, flowering trees grew in North America by the Turonian age, showing that these large trees were part of the forest canopies there nearly 15 million years earlier than previously thought.
Chinese Cretaceous fossil highlights avian evolution
A newly identified extinct bird species from a 127-million-year-old fossil deposit in northeastern China provides new information about avian development during the early evolution of flight.
Parasites discovered in fossil fly pupae
Parasitic wasps existed as early as several million years ago.
More Fossil News and Fossil Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at