26 September 2012

Mountain gorillas seen disarming poachers traps!

Everyday, animal trackers set out from the Karisoke Research Center into an isolated area of Rwandan rainforest aiming to find and disarm as many of the dangerous and illegal traps set by poachers as they can find. The trackers efforts are crucial in helping to protect the extremely rare mountain gorillas (Gorilla beringei beringei) that inhabit the region, which are classified as being 'Critically Endangered' by the IUCN and are predicted to become extinct within 10 years if we fail to conserve them.

When tracker John Ndayambaje set out one morning he was fully expecting to see poachers traps. Sure enough, he located a clan of gorillas and spotted a snare trap nearby. Although many poachers don't set snare traps to catch gorillas, as adults of the species are easily strong enough to break free, they are capable of killing juveniles so he knew that he must disarm it.

When John moved to approach the trap however, a silverback called Vubu grunted at him, presumably warning him to stay away. As John watched, two younger gorillas named Rwema and Dukore made their way over to it and carefully broke it, working confidently and quickly, which suggests that they've had extensive experience with the traps in the past. Rwema and Dukore then searched the surrounding foliage, joined by a third member of the Kuryama Clan called Tetero, and disarmed several more traps that John hadn't yet seen.

Rwema and Dukore work together to disarm a snare trap set by poachers.

This remarkable ingenuity has undoubtedly arisen in response to the very real dangers that the traps pose and is a superb example of mountain gorilla intelligence and their ability to learn. Researchers at the Karisoke Research Center believe that the gorillas watched human trackers tackling the traps and copied how they disarmed them. Although fascinating to watch, Veronica Vecellio (the Centre's gorilla program coordinator) was not surprised by the events and said that she is "always amazed and very proud when we [the Centre's researchers] can confirm that they are smart".

18 September 2012

Mirrors can cure phantom pains? Who knew...

Many people who have lost limbs in accidents, to amputation and even those born without correctly formed limbs, experience strange sensations in the absent limb or appendage. These feelings are known as phantom sensations and are very common, with around 70% of amputees experiencing phantom limbs.

Although scientists do not know what causes phantom limbs definitively, the common consensus is that the sensations are formed by the reorganisation of somatosensory cortex in the brain. It is believed that once the nerves for the missing limb stop receiving stimuli, they are removed by the brain to give more room to functional neurones. This also explains why a person's hearing gets better if they lose their sight - by replacing the now redundant 'eye processing' neurones with those that deal with hearing, the brain can analyse sounds more efficiently. Phantom limbs are thought to occur when this reorganisation is maladaptive, or is not fully completed, so that the brain still receives phantom signals from neurones for limbs that are no longer present.

The symptoms of phantom limbs offer some support for this theory since the sensations that patients experience are often similar. Usually, patients describe the phantom limb as being shorter than the original was. The difference in size can be very pronounced, being as much as 6 inches shorter in some cases! Many patients also describe feeling itches and tingling sensations in their phantom limb, which are symptoms that can all be explained by the reduction in processing capacity for the limb in the brain.

Whereas this is all very interesting, the phantom sensations don't stop here for many patients and the majority of individuals who experience this phenomenon suffer from varying degrees of discomfort and pain. Phantom Limb Pain (PLP) is very common and, as with phantom limb syndrome, doctors don't really know why it occurs. There are 3 leading theories however, which all have strong support within the medical and scientific communities:

  • The first is called maladaptive plasticity and is the same as the theory discussed above, suggesting that PLP is the result of maladaptive changes in the neuronal distribution of the somatosensory cortex following amputation.
  • The second suggests that PLP is a result of the conflict between the signals from the missing limb's old neurones, which are telling the brain that the limb is there, with the information from the patient's eyes, which is telling them that the limb is not there. It is believed that the conflict between this information confuses the brain, leading to intense pain in the phantom limb.
  • The last generally accepted explanation suggests that vivid memories of limb positions kick in after it has been amputated, and that these memories hold the limb in a certain position that the patient is unable to alter.

Without further understanding of the causes of PLP however, it is unlikely that scientists can develop a 'fix all' cure for patients due to the complexity of the condition. This is a real problem for many patients of PLP since the condition is most likely neurological, meaning that pain killers have no effect as a palliative and attempts to use drugs have repeatedly failed in the past.

A promising treatment for PLP does exist however, which has been successful in many cases. The treatment was developed by Vilayanur S. Ramachandran and his colleagues in the 1990's and involves the use of mirrors to trick a patient's senses into thinking that they are moving their phantom limb. 

This trickery is accomplished using a mirror box, in which the patient places their healthy limb in one hole and their stump in the neighbouring one. The top of the box is covered over their amputated limb, which the patient then appears to see as being whole again by watching the reflection of their healthy limb. When ready, the patient is asked to perform  'mirror symmetric' movements in both limbs simultaneously. Their brain then interprets moving their phantom limb and appears to 'see' it moving so any conflicting signals disappear, allowing the limp to shift from uncomfortable, painful positions.

Ramachandran's mirror box. Patients suffering from PLP put their healthy and phantom limbs into the box and, due to  the reflection of the mirror, appear to have two healthy limbs again.

A good example for mirror box therapy (based on an actual case), would be to imagine that one of your hands has been amputated. Following the operation you experience the sensation that your missing hand is constantly clenched, with the feeling being so strong that you are continuously in pain. In the therapy you are asked to clench and unclench both of your hands at the same time. By appearing to see your phantom hand move, your brain interprets that it is now unclenched and the pain disappears. 

Regular sessions of mirror box treatment have been able to alleviate PLP in many patients until it eventually disappears by itself, which occurs in most cases given enough time. As with the causes of phantom limbs and its associated pain, scientists can only offer theories to how mirror therapy works and it is possible that we may never know definitively due to the complexity of the human brain. Developing our understanding of mirror therapy may help to resolve an exceedingly curious phenomenon that has long baffled scientists and medics alike.

13 September 2012

First new monkey discovered in 28 years!

Recently, a team of scientists have been cataloguing the animals present in the Tshuapa-Lomami-Lualaba region in the Democratic Republic of Congo. The area consists of around 6, 500 square miles of undisturbed forest and is one of the few unexplored areas left in Africa. Very early on, their efforts found the region to have an abundance of primate life, being home to bonobos and at least 10 other primate species, making it an important link in understanding the evolution of primate diversity.

Scientists have named the newly discovered Lesula monkey after the nearby Lomami River, calling it Cercopithecus lomamiensis.

What is even more remarkable than this significance, is what the researchers found in Opala, one of the towns that they were using as a base for their research. In a visit to a local primary school, the team was shown a young female monkey that was being kept as a pet by one of the directors. What is truly remarkable, is that this monkey was a member of a new species that had never before been seen by scientists. Known as a  lesula by the locals, the species belongs to the family of African guenons - a group which scientists previously believed that they knew very well! It appears that the two nearest rivers, the Congo and the Lomami, have isolated the species from its cousins so that the lesula evolved fairly independently via a process known as allopatric speciation.

Extensive investigation has revealed many more individuals of lesula kept in captivity in the surrounding area and individuals have been found living freely in the forest. It is hoped that the uniqueness of the species, along with the fact that many more undiscovered animals could be waiting in the forest, will be enough to legally protect the diversity of the area. Plans are already in motion to officially declare this protection, turning the Congo Basin into the Lomami National Park.

4 September 2012

Masters of subjugation

Slavery is unarguably a terrible thing that has sadly ruined the lives of countless human beings throughout our violent history. Slaves were used to build the Egyptian pyramids, constructed the Mayan temples and were even used as a source of profit for many European empires during their colonial histories. Fortunately however, slavery is now illegal and has been banned for centuries in many countries. Great Britain for example, passed the Slavery Abolition Act in 1833 that banned slaves being possessed or sold anywhere within the British Empire and its dependencies. Due to its negativity and historical importance, the concept of slavery isn't new to anyone. What may surprise you however, is that humans are not the only animals to have enslaved others and certain species of ants run their entire colonies using only conquered workers!

Rather unimaginatively, such species have been termed 'slavemaker ants' and can be found across the Americas, Europe and some parts of Asia. Slavemaker ants are usually rare, but highly successful species and colonies of around 3, 000 of the ants can have as many as 60, 000 slaves working for them that cater for their every need! In fact, the genealogy of slavemaker species shows just how successful they are as most species are completely unrelated to each other. This fact suggests that their behaviour has evolved independently on several different occasions, so enslaving others must be a beneficial and rewarding way for ants to live. 

Formica sanguinea is a species of slavermaker ant that is native to the British Isles, being found most commonly in the Scottish Highlands and in the south-east of England. The species is unusually large, growing to over a centimetre long, and organises itself into multiple 'platoons' of about 100 workers before an assault. Eggs and workers from the attacked nest are carried back to their 'mother nest' to be enslaved with pheromones secreted by the slavemaker queen.

Although subjugating behaviour is clearly advantageous for slavemaker ants now, why it evolved in the first place is confusing. This is because colonies of slavermaker ants are typically very small and prefer to attack only the biggest and most strongly guarded colonies of other species. As well as carrying high risk for the attacking ants, which may be wiped out in the attack (thus ending the colony as all of its members are required for each assault), the urge to enslave has come at a price and slavemaker ants are incapable of running a colony by themselves. In fact, slavemaker workers seem to have completely forgotten the basic foraging, building and nursing behaviours seen in all other species of ant and only their queen seems to be able to function normally (who lays new eggs of slavemakers).

The loss of these normal behaviours have come at the gain of new ones however, and slavemakers have many different tactics for invading nests. Their tactics are usually used to reach one of two different goals: some species invade an existing nest and take up residence there, while others destroy a nest and carry their unborn young/survivors back to their own queen.

Slavemaker invasion of existing nests is usually carried out using 'distraction' techniques. In such assaults, the majority of slavemaker workers attack the nest to provide a diversion for the colony and draw their soldier class into focusing on them. The pre-mated slavemaker queen then uses the ensuing medley to sneak into their nest with a small raiding party and kills their actual queen, whom she then mimics. This is accomplished by rolling in her pheromones (the chemicals that ants use to identify those of their own colony from hostile invaders) and thus, when the assault is over, the workers of the nest are none the wiser to the exchange and care for the slavemaker queen as their own while she produces more slavemaker ants.

Slavemaker species that seek to completely destroy a nest often have clever biological tricks up their sleeves as their numbers are normally too few to win in an all-out assault. Saying this, it should be noted that some species of slavemaker ant like F. sanguinea have grown to be very large and thus, do rely merely on brute force. Most species don't however, and perhaps the most interesting method used is seen in some South American species, which secrete a chemical that causes ants to abandon their nest. Once empty, the slavemaker workers simply enter it and take the unhatched pupae, carrying them back to their own 'mother nest'. Once these ants hatch, they accept the slavemaker queen's pheromones as their own and spend their lives serving her and her nest.

So there you have it! Ants that conquer the nests of other species and enslave their workers for their own colony's survival! Unlike human slavery however, this is unlikely to stop and ants will likely continue to master the art of subjugation for years to come...