Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Ancient raptors likely feasted on early man, study suggests

31.08.2006
A new study suggests that prehistoric birds of prey made meals out of some of our earliest human ancestors.

Researchers drew this conclusion after studying more than 600 bones from modern-day monkeys. They had collected the bones from beneath the nests of African crowned eagles in the Ivory Coast's Tai rainforest. A full-grown African crowned eagle is roughly the size of an American bald eagle, which typically weighs about 10 to 12 pounds.

Punctures and scratches on many of the monkey skulls have led some researchers to rethink which animals may have preyed on our human ancestors, said W. Scott McGraw, the study's lead author and an associate professor of anthropology at Ohio State University.

“It seems that raptors have been a selective force in primate evolution for a long time,” he said. “Before this study I thought that eagles wouldn't contribute that much to the mortality rate of primates in the forest.

“I couldn't have been more wrong.”

The results may also have important implications for the mystery surrounding the death of one human ancestor who lived about 2.5 million years ago.

Archaeologists discovered the skull of a 3½-year old ape-like child in a cave in South Africa in 1924. Researchers believed this child, called the Taung child (Australopithecus africanus), had been killed by a predatory cat. But McGraw said that puncture marks on the monkey skulls he examined closely resemble those found on the skull of the Taung child.

“Eagles leave very distinctive beak and talon punctures around the face and in the eye sockets,” “The skull of the Taung child has these same kinds of puncture marks.”

The study is online at the website of the American Journal of Physical Anthropology, and is scheduled for publication in the journal's October issue. McGraw conducted the study with Catherine Cooke, a graduate student in anthropology at Ohio State , and with Susanne Schultz, of the University of Liverpool , collected most of the bones for the study.

The best way to learn about an eagle's prey is to gather the remains that are in or near the raptor's nest, says McGraw.

“Eagles are ambush predators – they go in for the kill quickly,” said McGraw, who has spent much of the last 15 years studying primates in the Tai rainforest, which is in southwestern Ivory Coast .

“So the chance of actually seeing an eagle attack a monkey is extremely slim,” he continued. “Yet raptors are kind enough to leave all the bones around afterwards. That means we can work backwards and construct a prey profile based on what's left over.”

Over the course of three years the researchers collected some 1,200 animal bones discarded from 16 African crowned eagle nests. Slightly more than half of the bones (669) belonged to primates. The rest of the bones were from other, non-primate animals that the eagles preyed upon.

Most of the bones in the collection belonged to smaller monkey species, which weigh anywhere from 2.5 to 11.5 pounds as adults. But a third of the monkeys whose bones were part of the sample set would weigh anywhere from 13.5 to 24 pounds when alive. The majority of these bones were from mangabeys, the largest monkey in the Tai forest.

McGraw admitted that this finding surprised him. Mangabeys live primarily on the ground – all of the other monkey species live in the canopy of the rainforest. It makes sense that eagles would zero in on monkeys in trees, as these primates are presumably easier to spot and attack. Also, mangabey populations aren't as dense as other monkey species in the Tai rainforest.

“It appears that the crowned hawk eagle specifically targets these large, relatively rare monkeys,” McGraw said. “When we consider the density of the average mangabey population, the odds of an eagle encountering one of these monkeys should be small. But these mangabeys are turning up in nests more often than chance alone would predict.”

The finding suggests that birds of this size were quite capable of successfully attacking a young hominid.

Archaeologists think that the Taung toddler weighed around 26 pounds (12 kg). McGraw says that scientists think that a raptor about the same size as a modern-day African crowned eagle may have killed the young hominid.

“Many people thought that an eagle of this size wouldn't have enough strength to lift a primate the size of the Taung child,” McGraw said. “That's a non-issue, because eagles don't hunt and process their kills that way. They typically dismember their prey very quickly, and then take pieces of the carcass back to the nest.”

After identifying the bones, the researchers began to assess actual damage patterns on the bones.

The collection consisted mostly of skulls and the long bones of the hind limbs (namely the femur, or thigh bone, and tibia, a bone in the lower leg.) Smaller, more fragile bones are often destroyed during the attack, and can also rapidly decay in a rainforest environment.

Monkey skulls, shoulder blades and pelvic girdles showed the greatest amount of damage. Most of the skulls were fractured or punctured, presumably from the force applied by the grip of an eagle's talons. There were fractures in the eye sockets and at the base of most of the skulls, either from beaks or talons that had punctured the bone in order to retrieve soft tissue.

There were noticeable punctures and scrapes across nearly every shoulder blade in the sample. The ends of many of the long hind limb bones had been removed, apparently to get to the marrow inside.

The puncture marks on some of the monkey skulls are very similar to those found on the skull of the Taung child, McGraw said.

“This fossil is probably the most written-about, studied and handled hominid skull ever,” he said. “But almost no one had really bothered to look at skulls discarded from eagle nests. It's not that the damage was overlooked in the Taung skull, it's just that we didn't have the link to make sense of it.”

He went on to say that the punctures in the Taung skull probably aren't due to damage during the fossilization process; rather, these marks are instead a clue to what killed the small hominid.

“Those marks aren't from some large predatory cat, they're from an ancient crowned hawk eagle,” McGraw said.

The evidence from this study is also changing the way McGraw and his colleagues look at predator-prey dynamics.

“The findings suggest that birds of prey have been one of the most important selective forces in primate evolution for a long time,” he said. “There are other primate fossil collections around the world that may deserve a second look for evidence of wounds inflicted by raptors.”

The researchers received support for this work from the Leakey Foundation, the Wildlife Conservation Society, the Peregrine Fund, the National Science Foundation, the British Council and Ohio State.

W. Scott McGraw | EurekAlert!
Further information:
http://www.osu.edu

More articles from Studies and Analyses:

nachricht Smart Data Transformation – Surfing the Big Wave
02.12.2016 | Fraunhofer-Institut für Angewandte Informationstechnik FIT

nachricht Climate change could outpace EPA Lake Champlain protections
18.11.2016 | University of Vermont

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>