Influence of Parasites on Behaviour

Sometimes we think that we have understood something, then scientists comes up with new insights, which force us to rethink about that understanding. For example, over the past decade, insights about the gut bacteria which constitute our microbiome and might shape different aspects of our lives, from obesity to depression, have opened a new areas of scientific enquiry. The discovery of a "new body organ", the interstitial space, is another emerging area of research and understanding, which might have surprises waiting for us. Kathleen McAuliffe's book about parasites and how they might affect human behaviour relates partly to the role of gut bacteria, but has a wider scope. It did manage to force me to reflect about issues that I had not thought before.

About 50 years ago, when I had joined medical college in India, I used to think that almost all the things that could have have been discovered about human body and diseases had already been discovered. I imagined that technology might help us improve some things, like diagnosing some difficult to diagnose conditions, but I had no idea that in these 50 years scientific knowledge about some aspects of human body, such as genetics, was going to change so drastically. That is why I love reading books which give an understanding about human body and its influence on the changing practice of medicine.

McAuliff's book has a strange title, "This is Your Brain On Parasites", which does not sound very interesting, but its subtitle explains it better - "How tiny creatures manipulate our behaviour and shape society". This post is about this book, which I would divide into 2 parts - the first part is about different parasites which infest worms and insects and, change their behaviour; the second part is about humans. The latter is more speculative, it wonders how parasites and fear of illness might be influencing our sense of disgust and our behaviour towards "outsiders".

Parasites in Other Life Forms

In the first part of the book, McAuliff talks about researchers who have spent all their lives following the life cycle of a parasite and the surprising things they have discovered. McAuliff explains that searching for these stories was what led her to writing this book:The impetus for this book was a discovery on the Internet. I’m a science journalist and one day while foraging for interesting topics to write about I stumbled across information about a single-celled parasite that targets the brains of rats. By tinkering with the rodent’s neural circuits—exactly how is still a matter of fervid study — the invader transforms the animal’s deep innate fear of cats into an attraction, thus luring it straight into the jaws of its chief predator. This is a felicitous outcome not only for the cat but also, I was stunned to learn, for the parasite. It turns out the feline gut is exactly where the organism needs to be to complete the next stage of its reproductive cycle ... As I continued reading, more surprising news greeted me: The microscopic organism is a common inhabitant of the human brain because cats can transmit it to us when we come in contact with their feces. Perhaps the parasite was meddling with our brains too, speculated a Stanford neuroscientist associated with the research.
The stories of parasites entering the bodies of their hosts and changing their behaviour to suit their own desires, are like the stories of ghouls and spirits taking over and turning living beings into zombies - fascinating and frightening. At the same time, this part of the book explains the different obstacles these scientists had to overcome in their single-minded passion about one worm or one insect, over periods lasting decades. It is a pity that most of their names remain in obscurity.

For example, there is the story of the scientist Janice Moore who got interested in the life-cycle of a tapeworm and studied how it passes part of its beginning life in the ants and then it makes the ants go crazy, so that they climb on the the tip of grass and wriggled in such a way to attract the sheep to come and eat those grass-blades. Thus the worm reaches the brain of the sheep, needed for the next phase of its life-cycle.

From crazy fishes flipping on their belly on the surface of water so that they were eaten by some cranes to cockroaches meekly following the wasps to their nests so that wasp could deposit its eggs on its tummy and when wasp-babies come out they could have fresh cockroach meat, the stories are incredibly interesting and morbid.

They also made me think about some flamboyant persons with attention-seeking behaviours and wonder if they might have some worms in their brains? We do have some popular ways of sayings in Hindi in India, such as "Iske dimaag mein keeda laga hai" (His/her brain has got a worm), which sounds very similar to these stories.

Parasites and Human Behaviour

In this part of the book, McAuliff focuses on human psycho-pathology. These are more of hypothesis rather than scientific studies, about how the bacteria living in our bodies might be influencing our behaviour (though these bacteria are not really parasites, rather these are symbiotic organisms, as they get nutrition from us but they also provide benefits to us such as vitamins).

Cruickshank, in her review of McAuliff's book in New Scientist has critiqued this part:

Oblivious, McAuliffe skips into attention-grabbing territory armed with only the flimsiest of evidence. She claims, for example, that infection makes us more sociable and sexually voracious as the parasite seeks to infect others. This is based on a study that followed people given a flu shot (it being unethical to give people actual influenza). The subjects’ increased sociability might have been due to viral manipulation, but for my money it’s more likely they were simply feeling confident about being protected from infection.

McAuliff may not have evidence for most of the things she writes in this part of the book, but in terms of human psycho-pathology, they do raise some interesting hypothesis.

Conclusions

Studying the influence of bacteria and parasites on human behaviour is a field in expansion and new discoveries are already being made, which have many practical implications. For example, understanding how the malaria parasite influences mosquito behaviour and how it changes human physiology, can help us in diagnosing it and fighting against an infection which kills hundreds of thousands of persons each year. Some months ago, I had seen a TED video by James Logan about how dogs may be able to identify persons with malaria parasite, because the parasite makes our bodies secrete a chemical in our sweat, which attracts uninfected mosquitoes to come and bite us, and dogs can be trained to identify the persons with this chemical in their sweat.

I found this book hugely interesting and read it in a span of a few days, almost like a thriller. It is true that in terms of influence of micro-organisms and parasites on human behaviour, this book is speculative. However, it might influence young researchers to study these areas and see if such infections/infestations can be implicated in the causation of conditions which are yet not properly understood, like schizophrenia and Alzheimer disease.

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The City of 47 Ronin

The tiny town of Ako in south-west Japan is known for the story of 47 Ronin. The city has a beautiful Shinto shrine with the statues of those 47 warriors who had chosen to become outlaws to avenge the death of their lord.

I had watched the film "47 Ronin" starring Keanu Reaves, which was based on this story. A couple of years ago when I was in Okayama for a meeting organised by Sasakawa Health Foundation, I had discovered that it was not very far from Ako. Thus, I took that opportunity to go and visit this city and to become familiar with its famous legend. This post is about my visit.

Samurai and Ronin Traditions in Japan

The Samurai (Bushi) warriors became an important group in Japan in the 12th century when they worked for feudal lords. Those lords along with their samurai were the real rulers of Japan.

The samurai followed a code of conduct called Bushido. According to the Bushido, when a Samurai became master-less, for example by the death of his master, he was expected lay down his arms and to commit suicide by Seppaku (by plunging a knife in the stomach). Any samurai who did not kill himself was known as ronin, a warrior without honour.

The ronin were looked down upon by their fellow samurai and by the society. They were ridiculed and faced public humiliation.

In 1868, with the Meiji reforms, the military control of country was replaced by a centralised bureaucratic governance. This ended the role of samurai.

I feel that the idea of warriors without a lord committing suicide according to an ethical code sounds similar to the ideas in medieval India about widows letting themselves be immolated along with their husbands' bodies under the "Sati" rituals. Such ideas may seem acceptable while one is wrapped inside and isolated in those ritualistic beliefs. Perhaps some can argue that the suicide bombs by radicalised Islamists are similar rituals, though those are fundamentally different since they also involve additional killing of unsuspecting persons. However, an unwrapping of self and a contact with wider world makes such ideas of ritualised suicides seem like aberrations and a kind of mental illness (though the traditionalists won't agree with this view).

Looking at the figures of Ronin through modern eyes, I feel that seeking revenge for their lord's death was a better option for the warriors, than killing themselves through ritual suicide, though in the Ako story, they did kill themselves after taking their revenge.

The Ronin of Ako - Historical Background

"Ako vendetta", was a historical event in which a group of ronin avenged the death of their master Lord Naganori Asano.

In 1701, Lord Asano, the Daimyo of Ako, was forced to commit ritual suicide by Kira Yoshinaka, a scheming official of the imperial court. However, Asano's samurai did not commit seppaku as foreseen by the Bushido and instead became ronin. Their initial attempts to avenge the death of Lord Asano were unsuccessful. Finally, those 47 ronin managed to kill Kira at Sangakuji in Edo (now known as Tokyo).

Even though by taking up the arms after the death of their lord, they had violated the samurai code of conduct, their honourable action in avenging Lord Asano was recognized. Thus after their revenge, those 47 ronin were allowed an honourable death by committing seppuku.

During the Meijo era (1868-1912), the story of 47 ronin became very popular all over Japan through songs and traditional plays such as kabuki. It was a tale of persistence, honour and sacrifice. The Hollywood film "47 Ronin" (2013) was inspired from this story.

The City of Ako

Ako is located in the Hyogo prefecture in south-west Japan, between Osaka and Okayama. Its railway station is called Banshu-Ako. It is a small coastal town facing the inland sea. It has a population of around 50,000.

Ako is located on the banks of Chikusa river and has a good network of canals. On 14 December each year, Ako celebrates the Gishisai festival to remember the 47 ronin, with a parade of the warriors dressed in old costumes and illuminations with lanterns.

Reaching Ako

When I told my Japanese friends that I wanted to visit Ako, they were a little surprised. The city's name was not so familiar to them. I had to explain the story of 47 Ronin to them. Even at the tourist office in Okayama where I went to ask for information, they were surprised that I wanted to go to Ako. They were not sure if there was much to see in Ako. However, as you can see from the images, it is a beautiful city and is worth visiting.

To reach Banshu-Ako, I took the Ako line local train from Okayama. The journey took around an hour. Passing through small towns and villages (including Bizen and Osafune, two famous small towns in this region) along with verdant mountains, it was a beautiful journey.

The local train network also connects Banshu-Ako station to Himeji and Kobe on the east.

Places to visit in Ako

The city centre is small. The places to visit include the ruins of the castle of Ako and some shrines and temples. Among the shrines, the most important is the Shinto shrine linked with the 47 ronin located near the castle.

Among the temples, the most important is Kagaku temple. The Kagaku temple, the Ako castle and the Shinto shrine of the 47 ronin, are all at a walking distance from the railway station. The main street in front of the railway station leads to the castle. A map of the city in the square facing the railway station will show you all these landmarks. The city, including the railway station, is full of banners, posters and tiles with images of the different Ronin warriors.

In Kagaku temple, I met a group of Japanese artists, who were visiting the city and making drawings of its different buildings. They were curious about me but we had to communicate with gestures as they could not understand English.

The Kagakuji (or Sengakuji) was the family temple of the Asano family. It is a beautiful Buddhist temple with a giant bell and with different shrines. I was told that Kagaku temple has the tombs of the 47 Ronin, each marked by the number "7" to denote death by seppuku. However, I had also read that the tombs of the 47 ronin are in the cemetery of the Sengakuji temple in Tokyo, so I am not sure if the tombs in the Kagaku temple of Ako were real or not. I tried asking about them but was unable to make myself understand and thus, did not see them. In the temple, there were no sign boards indicating the tombs.

Ako Castle and Oisho Shrine of the 47 Ronin

When I reached the castle, some of the persons from the group of Japanese artists had also reached there and they smiled at me. There was no ticket to enter the castle, which does not have many things to see. Imposing walls surrounded the castle ruins. This castle was destroyed by the bombings during the second World War, and its walls have been recently rebuilt to recreate the old ambiance.

Inside the walls, most of the ruins were just empty spaces marked on the floor explaining the different building of the old castle. The castle was built by Naganao Asano Ako, the third lord of Ako domain and the grandfather of Naganori Asano. It had taken them 13 years to built this castle. I was told that the rooms of the Lord and his wife were marked on the floor, but since it was only in Japanese, I could not identify them.

On one side inside the castle, there is a short and squat tower (Tenshudai), where you can go up and have a panoramic view of the area.

A winding path passing near the Ako Museum of History and the Gardens of Ako castle took me to the shrine behind the castle. It is marked by a row of statues of the 47 ronin on both the sides of the path. This shrine is also called Oisho shrine to remember Oisho, the leader of those Ronin.

Each statue of the ronin was different - showing men of different age groups, each with his favourite weapon, some of them standing while others were sitting. Against the background of the castle ruins, the two rows of statues lining the path leading to the shrine made a powerful visual impact.

Inside the shrine gate (Torii), on the two sides were two giant wooden statues of pot-bellied old men. The one on the left was Daikoku Sama, symbolising luck and matrimonial happiness. The one on the right was Ebisu Sama, symbolising success in business and trade.

Inside the shrine, there were different memorials for persons to express their admiration for the warriors - for example, through the streamers of paper-cranes usually placed in cemeteries. The courtyard also has a statue of Oishi Kuranosuke, the leader of the Ronin.

One of the shrine buildings was Homotsu-Kan or the treasure hall, entry to which has a ticket. Inside you can see the Oishi "Glass of Rules" for the Ako samurai. The rules included the following - do not fight, do not spill drink from your mouth and do not force a non-drinker to drink.

A path from the Shinto shrine led to castle garden - a beautiful garden just outside the castle ruins. When I visited it in April 2017, it was not yet completely done and some parts were closed. Still it seemed to be landscaped beautifully with a canal, some gently bubbling fountains and a quaint bridge.

The garden ruins also include two ponds, both beautifully designed to evoke feelings of peace and harmony.

Conclusions

I could visit Ako only for a few hours. It was a rainy day. I knew that there would not be enough time to visit the historical museum or to go to the sea coast in Ako. On the other hand, I had thought that I will be able to visit Chikusa river and a couple of other shrines near the railway station. However, the visit to the castle and the Oisho shrine took most of my time and I could not do more, I had to rush back to catch the train to Okayama.

I think that Ako merits a visit. If you are visiting south-west Japan, such as Okayama or Kobe, it would be worthwhile keeping a morning to visit it.

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