Many farmers will agree that pigs can show quite extraordinary cognitive abilities. New research from the University of Cambridge suggests that pigs show awareness when exposed to a mirror test. Pigs with prior experience of mirrors seemed to realise that they were looking at a mirror image and correctly searched for a hidden food bowl seen in the mirror away from the mirror, while pigs with no prior experience searched for the food bowl behind the mirror.

Awareness is a difficult thing to study or even to define. Traditional it is defined as the ability to perceive, to feel and to be conscious, but this definition is very difficult to measure. Thus while we can be fairly certain that we ourselves are aware, we can be less certain that our friends are aware but at least they can tell us so. Animals cannot. However, there is one way to assess the self-awareness in animals and human infants. Put them in front of a mirror and looks for signs that they recognise themselves. When human infants are exposed to mirrors age and then fooled to think that a video playback of themselves with a sticker on their head was a mirror, 0% of two year olds, 25% of three year olds and 75% of four year olds reached for the sticker. 

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The micrograph shows abundant (malignant) plasma cells with the occasional Mott cell, a plasma cell with an intracytoplasmic Russell bodies (an eosinophilic uniformly staining membrane bound body which contains immunoglobulin). Wikimedia Commons, Author: Nephron

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An ant-acacia Acacia collinsii like the one on which the vegetarian jumping spiders were found. Photo taken by Thomas Hesselberg.

The spider belongs to the group of jumping spiders, which are usually active hunters without a web. They have a good vision and use it stalk prey at a distance before they are within jumping distance. However, this particular jumping spider does not hunt any prey, but spend its life on a plant. Not just some plant though, but an ant-acacia, which is a plant that lives in a close mutualism with an ant. The acacia offers the ants housing in its thorns and food in the form of special fat and protein rich Beltian bodies and in return the ants protects the plant against herbivores and other encroaching plants.

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Aylin Hammann, PhD-student at the Institute of Sanitation Science in Greifswald, Germany, shows how to desinfect the hands properly. photograph: Janke/UKG

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Humans do show some height variation among population, here a European with Pygmies at the beginning of the last Century. Scan of Collier's New Encyclopedia, Volume 1 (1921). Courtesy of Wikimedia Commons.

We might think that whereas most animals in the same species looks alike, we, humans, show a lot of individual variation. However, new research shows that in fact humans are much similar than we think. The scientists compared variation in length (height) and body mass in various human populations and compared it to animal populations. Surprisingly, they found that humans show some of the lowest levels of variation in height, whereas variation in body was around the average variation found in animals.

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The tiger. The protection of big allrounders like tiger, wolf or lion may play a key role in ecosystem stabiltiy (photo: U.S. Fish and Wildlife Service)

Computer models can contribute to the understanding of complex systems in nature. Ecosystems belong to complex systems which are influenced by numerous correlated factors. Food chains for example are part of ecosystems and difficult to investigate in all with the methods of field ecology. It is known that food webs are stable over long time periods, the interactions between different species (predators and prey) are constant. Yet when ecologists try to calculate models of such correlations they face some obstacles: they have to reduce usually many factors to get reasonable scientific output from their models. So still conclusions drawn from results are still constrained. Now scientists from Austria, Germany and the US revealed fundamental legalities of stability in ecosystems: the more diversified the prey species are on which a predator at the top of a food chain feeds the more stable is the ecosystem in which it lives. Accordingly a food chain is most stable if the prey species in the center of a food web or a food chain have various predators. The scientists used a new method  developed by a workgroup of the Max-Planck-Institute of the Physics of Complex Systems.

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