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 The Great Unknown: Risk-Taking Behavior in Adolescents
19.01.2017 | Max-Planck-Institut für Bildungsforschung

nachricht A sudden drop in outdoor temperature increases the risk of respiratory infections
11.01.2017 | University of Gothenburg

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: Quantum optical sensor for the first time tested in space – with a laser system from Berlin

For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.

According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Tracking movement of immune cells identifies key first steps in inflammatory arthritis

23.01.2017 | Health and Medicine

Electrocatalysis can advance green transition

23.01.2017 | Physics and Astronomy

New technology for mass-production of complex molded composite components

23.01.2017 | Process Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>