They are lethal weapons that stags crash together when duelling. John Currey, from The University of York, UK, has been intrigued by the mechanical properties of bone for over half a century and has become fascinated by the mechanical properties of antler through a long-standing collaboration with Tomas Landete-Castillejos at the Universidad de Castilla-La Mancha.
'Antlers look as if they are dry,' says Currey, 'but no one knew if they really are dry when used in contests'. Curious to find out whether red deer antlers are used wet or dry when duelling, and how this affects the antlers' mechanical properties, Currey headed south to La Mancha to test the mechanical properties of red deer antlers and publishes the discovery that dry antler is stiff and tough on 27 November 2009 in the Journal of Experimental Biology at http://jeb.biologists.org.
But before the team could begin testing the antler's strength, they needed to find out how dry the bones were. Collecting freshly cut antlers from the university farm and a local game estate just after stags had shed the antler's protective velvet, Currey, Landete-Castillejos, José Estevez and their colleagues weighed the antlers each week to find out how much they dried. Amazingly, over the first 2 weeks, the antlers lost a colossal 8% of their weight, compared with 1% weight loss if they were cut at other times of the year. Eventually the weight loss stabilised and the antler's humidity was in balance with that of the surrounding air. It was clear that the antlers were dry when the stags began duelling.
But how did this water loss affect the bone's material properties in comparison with those of normal bones, which function internally and are always wet? Would the dry antler make a better weapon than wet bone?
The team prepared 40 mm long blocks of dry antler and wet deer femur and measured the amount of force needed to bend the blocks to find out how flexible the materials were. Even though most bones are relatively brittle and inflexible when dry, the team found that the dry antlers are almost as stiff as wet bone: which is ideal for weapons that have to survive a lengthy pushing contest after the initial clash.
But how 'tough' was the antler? How much energy could it absorb in the initial crash? Applying a force to the middle of the blocks of bone and gently increasing it until the bone broke, the team plotted a curve of the bending force against the amount that the bone bent. Calculating the amount of energy that the antler could absorb before shattering, Currey found that the tissue was incredibly tough: 2.4 times tougher than normal wet bone. And when Currey measured the amount of energy that the dry antler could absorb in an impact, he was surprised and pleased to see that it could survive impacts 6 times greater than the impacts that shattered wet femur. The dry antler was tougher than wet bone and ideally suited to survive the stags' initial clash.
So dry deer antlers are simultaneously stiff, yet tough, making them perfectly suited to their role as a weapon. And the deer seem to have solved a problem that has puzzled engineers for decades. 'It is very difficult to make anything that is both stiff and tough,' says Currey, but it seems that duelling deer solved the problem eons ago.
The irresistible fragrance of dying vinegar flies
16.08.2017 | Max-Planck-Institut für chemische Ökologie
How protein islands form
15.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
Researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, the Italian Space Agency (ASI), and the Instituto Geofisico--Escuela Politecnica Nacional (IGEPN) of Ecuador, showed an increasing volcanic danger on Cotopaxi in Ecuador using a powerful technique known as Interferometric Synthetic Aperture Radar (InSAR).
The Andes region in which Cotopaxi volcano is located is known to contain some of the world's most serious volcanic hazard. A mid- to large-size eruption has...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
16.08.2017 | Physics and Astronomy
16.08.2017 | Materials Sciences
16.08.2017 | Interdisciplinary Research