Research Center for Human Evolution
Research Center for Human Evolution
News Article | May 17, 2017
In 2012, a Time magazine cover showing a three-year-old kid breastfeeding caused a ruckus. Well, that photo would have been just fine in the orangutan world: young orangutans keep nursing for eight years or more — longer than any other mammal, according to a new study. Researchers analyzed the teeth of four wild orangutans for an element absorbed from breast milk, barium. The presence of barium suggested that breastfeeding continues in cycles for at least eight years, helping young orangutans get their nutrition even when other food sources like fruits are scarce. The findings, published today in the journal Science Advances, deepen our understanding of these elusive primates — and could help scientists in their efforts to protect them from extinction. Orangutans are the world's largest tree-climbing mammals. The big apes live in forests in Indonesia and Malaysia — unpredictable environments with limited nutritional resources. Because they evolved in this environment — never really knowing when the next meal is — “their whole life history is kind of slowed down,” says Cheryl Knott, an associate professor of anthropology at Boston University. Their metabolism is slower than that of other apes, they reproduce later in life, and they nurse their babies for longer. Scientists, in fact, have long known from observations in the field that young orangutans nurse for years after birth. But getting accurate data is hard, because suckling often happens on remote tree tops or even during the night, says study co-author Christine Austin, a postdoctoral fellow at the Icahn School of Medicine at Mount Sinai. “These are animals that are very difficult to study,” she says. So the team behind today’s research decided to look at milk intake by studying the teeth of wild orangutans. Teeth “are basically a biological hard drive that’s reporting every day what’s going on in your body,” Austin says. Literally every day of childhood is recorded in teeth — and that record can be analyzed to understand what the person (or monkey) was eating or how healthy he was. That allows “biological anthropologists an unprecedented window into the past,” lead author Tanya Smith, at the Australian Research Center for Human Evolution at Griffith University, writes in an email to The Verge. So the researchers got ahold of the teeth belonging to four wild orangutans that were shot by collectors during expeditions, and stored at the Humboldt Museum in Berlin, the State Anthropological Collection in Munich, and the Harvard University Museum of Comparative Zoology. (At least two of the orangutans were shot more than 100 years ago, Smith says. “This was a normal way for Western countries to obtain zoological material for research collections,” she says. But today, orangutans and all great apes are protected, and the practice is forbidden.) The researchers cut the teeth open and fired a laser at them to vaporize a small bit of tooth material. That material was then analyzed to calculate the chemical components, including barium, which is present in breast milk. By calculating how much barium was present through the tooth “history,” the researchers were able to determine the breastfeeding behavior of the four specimens. For example, they saw that after the first year, barium levels generally decreased. That’s because the orangutans were feeding exclusively on milk for the first year of their lives, but then began eating also other things, like leaves and fruits, relying less on breast milk. They also saw that breastfeeding happened in cycles — sometimes the babies were suckling more, sometimes they were sucking less. That’s probably because whenever other food sources were scarce, the babies drank more breast milk, and vice versa. But breastfeeding continued into the eighth and ninth year of life. That’s longer than other primates. Chimps, for example, nurse until about five years old, Knott says. For humans, the time frame varies, but the American Academy of Pediatrics recommends that babies be exclusively breastfed for about the first six months of life. Breastfeeding can then continue for one year, or as long as the mother and baby want, the guidelines say. The findings corroborate what we already suspected from field observations, Knott says, but also add more information on the cyclical nature of breastfeeding in orangutans. The information could help scientists in their efforts to protect orangutans from extinction. The animals are endangered because they’re very slow to reproduce — females wait until they’re 10 or 15 to reproduce, and they give birth once every five years at most. Sometimes they wait as long as 10 years between babies. Better understanding how breastfeeding works, and how the environment plays a role in it, is key to protect the animals, Knott says. And there’s no time to waste. A century ago, according to the WWF, there were around four times as many orangutans in the world as there are today.
Moreno D.,French Natural History Museum |
Moreno D.,Rovira i Virgili University |
Moreno D.,Institute Catala Of Paleoecologia Humana I Evolucio Social |
Falgueres C.,French Natural History Museum |
And 13 more authors.
Quaternary Geochronology | Year: 2012
The Sierra de Atapuerca (Northern Spain) is characterized by a well-developed karst system where several major archaeological sites have been discovered, attesting an almost continuous hominin occupation of the area during the whole Pleistocene period. Previous geomorphological studies showed a connection between genesis of the karst system and the evolution of the nearby Arlanzón river Valley. However, numerical dating results were missing to refine the chronostratigraphical framework of the Arlanzón valley's fluvial incision. To address this, we applied the Electron Spin Resonance (ESR) dating method to sedimentary optically bleached quartz grains from several fluvial terraces. Nine samples were collected from five of the 14 identified terraces. The ESR age results are stratigraphically coherent and in general agreement with both previous geomorphological observations and available palaeomagnetic data. Consequently, an ESR chronology of the geological evolution of the Arlanzón valley is proposed, which can be then correlated to the sedimentary sequence of the palaeoanthropological site of Atapuerca Gran Dolina. Our results provide important information about the chronology of hominid occupation in this area during Early and Middle Pleistocene. © 2012 Elsevier B.V..
Pares J.M.,Research Center for Human Evolution |
Sahnouni M.,Research Center for Human Evolution |
Sahnouni M.,Indiana University Bloomington |
Sahnouni M.,Center National Of Recherches Prehistoriques |
And 5 more authors.
Quaternary Science Reviews | Year: 2014
The question of the earliest hominid settlements in northern Africa has been under debate for a number of years due to the lack of precise chronologies. Here we present new paleomagnetic data that supports an Olduvai Subchron age for the archaeological sites at Ain Hanech and El-Kherba, in northern Algeria. Our study is based on a 22m-thick magnetostratigraphy of the Ain Hanech Formation, which includes contextualized Oldowan and Acheulian lithic tools. Characteristic remanent magnetization directions were obtained from both thermal and alternating field demagnetization procedures of specimens from twenty five sampled horizons. Our results reveal the presence of the Olduvai Subchron in the upper part of the stratigraphic section, constraining the age of these important archaeological sites in northern Africa. © 2014 Elsevier Ltd.
Pares J.M.,Research Center for Human Evolution
Frontiers in Earth Sciences | Year: 2015
The use of the Anisotropy of Magnetic Susceptibility (AMS) has become a rather common practice in Earth Sciences since the pioneer note by Graham (1954). The versatility of the technique, and the rapidness in obtaining and processing AMS data largely improved in the past thirty years, and has generated a wealth of literature, notably on mudrock fabrics. The assessment of the current trends in magnetic fabric studies reveals that AMS has one of its largest potential in sedimentary rocks from structural settings where the ductile component of deformation is cryptic or hindered by the brittle component. Abundant evidence provided by AMS data reveal that deformation extents beyond the deformation or cleavage front in contractional settings, including fold-and-thrust belts and active accretionary prisms, configuring magnetic fabrics as a standard method for fabric quantification in deformed sedimentary rocks. © 2015 Parés.