The Aoshima island in the 21th century is famous as a cat island, though, its history is relatively short.
The history of the Aoshima Island began as late as in 1639 when a fishermen family discovered sardine fishery nearby and settled on the then uninhabited island. Thereafter, the population increased and peaked at 889 in 1942, then decreased to 102 in 1984, and 16 in 2012.
As the human population decreased, the feline population increased. In the 2000s, when the human population deceased to less than fifty, the feline population began to rise. In 2015 the human population was 16, while the feline apparently was 120.
The feline population, therefore, surged just in a decade in the beginning of the 21st century. What happened in that decade? Considering that almost no human beings have immigrated to the island in that period of time, it is highly likely that very small number of, if any, felines have immigrated. So, the feline population growth probably was caused by cats' reproductions under poorly controlled conditions, in which, cats had momentum to outnumber humans.
What we see today on the Aoshima Island, therefore, is the result of the rapid population growth on a genetically isolated land; that is the 'ginger explosion'.
Many cats on the Aoshima Island wear orange coats.
But are there really significantly many orange cats on the Aoshima Island compared to the mainland? If so, what is the proportion of orange cats?
What makes a cat a ginger, called a red mackerel tabby, is an orange gene (O) which is dominant to its allele, a non-orange gene (o). The orange gene exists only on X chromosome. So a ginger Tom, who has only one X chromosome, has one orange gene (Oy), while a female cat has either one (Oo) or two (OO). A female cat having two orange genes, or a homozygous genotype (OO), is a ginger queen. A female having only one orange gene, or a heterozygous genotype (Oo), wears orange and black mixed coat, which is called tortoiseshell. If a tortoiseshell cat has a piebald gene which makes a part of the coat white, she is a tricolor cat, which is called calico.
A ginger tom has an orange gene (Oy). A ginger queen has a homozygous genotype (OO).
A tortoiseshell queen has a heterozygous orange genotype (Oo).
A calico queen also has a heterozygous orange genotype (Oo).
A non-orange tom has a recessive gene (oy). A non-orange queen has a recessive homozygous genotype (oo).
Firstly we surveyed the cats' coat colors.
Cat coat colors on the Aoshima Island
Then we classified them according to orange genotype. On the premise that the sex ratio is 1:1, frequency of each genotype is uniquely determined.
Orange genotype of cats on the Aoshima Island
From this classification, the frequency of orange gene (O) works out to be 56 per cent. According to the zoologist Ken Nozawa, who conducted a comprehensive survey of cat genetics in Japan from 1975 to 1989, the orange gene (O) frequency in Japan was 31 per cent (*1). The frequency probably has not changed much since then, so, the Aoshima cats' orange gene frequency is significantly large.
So, why do so many the Aoshima cats have orange genes?
There are two possible scenarios; the first one is that the majority of the cats on the Aoshima Island incidentally had orange genes already in the 20th century before the population grew. If the frequency of the orange gene in the offspring was high, the frequency in their descendants would also be high. It is called founder effect, in which, a small number of individuals who migrate to a new land determine the genetic variation of their offspring on the land.
The second scenario is that orange cats would have been more adapted to the environment of the island and successfully outnumbered its allele. But there seems to have been no remarkable feature of the environment on this island but that cat-loving tourists have come to the island since the Aoshima Island became famous as a cat island.
If cats live on food given by tourists, their friendliness would make survival sense. According to a research conducted in 2012, ginger moggies are perceived by their owners as friendly and lovable (*2),
Are you friendly because you are a ginger?
But as far as we have seen a lot of friendly cats wearing various color coats on other cat islands, we do not say that orange cats are distinctively friendly with humans.
Not only gingers but also brown mackerel tabbies are friendly with tourists.
What is certain is that, on the Aoshima Island, compared with on the mainlands, many cats are unafraid of humans. They seem pleased to interact with every tourist.
This cat is so friendly that she comes so close to the camera that her image is extremely blurred.
So, why are the cats on the Aoshima Island so friendly with tourists?
One of the possible reasons is that, on this island, kittens have many chances to interact with various types of humans. Among the tourists are men and women, old and young. Unlike a household pet cat who interacts only with his or her owner, kittens on the Aoshima Island can interact with various types of human beings.
Not only adult cats but also kittens are friendly with tourists.
Cat experts say that whether a cat can be socialized with humans depends on when he or she begins interacting with humans. According to the research conducted in the 1980s, kittens handled by humans from their third week were happy to sit on a human's lap, but those whose contact with humans had been delayed to seven weeks jumped off a human's lap within half a minute. Kittens who had not been handled by humans during their first fourteen weeks stayed put for less than fifteen seconds (*3).
So what about the cats on the Aoshima Island? By measuring how long a cat sits on a human's lap, we may estimate how early he or she has begun interacting with humans.
11:23:40 A black mackerel tabby gets on a tourist's lap.
11:27:52 In four minutes the cat begins to purr, then snore, while another cat comes and grooms him.
11:43:32 He turns clockwise to be more stable.
12:41:06 Finding a stable position, he stays put for more than 30 minutes.
What we figured out is that, on this island it is not a cat's friendliness but a human's patience that determines how long the cat sits on the human's lap. The mackerel tabby got off the researcher's lap not because he wanted to do so but the researcher gave up measuring an accurate time of the cat's sitting on his lap. The researcher had been exhausted when he had kept the cat on his lap for no less than 70 minutes. If the researcher was more patient, the mackerel tabby probably have been on the researcher's lap for additional 60 minutes or perhaps even longer. Now that we do not know how long a cat sits on a human's lap, it would be difficult to estimate how early in his life he began interacting with humans.
The mackerel tabby, however, probably had opportunities of interacting with unfamiliar people in his very young days, and that is also the case of many other cats who have almost no fear of humans. We see today on this island several lap cats.
There are several cat islands in Japan, but there is no island on which so many cats like to be on tourists' laps as on the Aoshima Island.
Why do they like to contact with tourists? On of the probable reasons would be that on this island tourists are all cat enthusiasts. Compared with other cat island, the Aoshima Island is difficult to get to. The ferry shuttling between Iyo-Nagahama on the mainland and the Aoshima Island is small and shuttles only twice a day. The number of tourists a day is limited to from 34 to 68 (*4). So in holiday seasons the ferry is possibly full and some tourists cannot board and have to abandon the journey or try it another day. What discourages tourists furthermore is that the ferry is cancelled frequently in winter. During a stormy season the ferry service is cancelled once in three days. In a bad weather, a cancellation lasts seven to ten consecutive days.
The morning ferry leaves Iyo-Nagahama at 8:00 and arrives at the Aoshima Island at 8:35. It stays at the Aoshima only 10 minutes, leaving the island at 8:45; almost all the tourists go back to the mainland by the afternoon ferry which leaves the Aoshima at 16:15. Their sojourn, therefore, extends to seven hours and forty minutes.
What do the tourists do in such long hours? On this island there are no accommodations available, no restaurants, no shops, no casinos, no spas. During their sojourn, the tourists take photos of cats, feed cats, and play with cats. There is no tourist attraction on this island but cats.
A tourist on the Aoshima Island can readily take photos of beautiful pawpads.
Feeding cats is allowed in a designated place near the community center.
Cats on the Aoshima Island like playing with tourists.
Tourists on this island, therefore, are all more or less enthusiastic feline fanciers. They know well how to interact with cats; they don't do what cats dislike and allow cats to do what the cats like to do.
The cats on this island likely trust tourists coming all the way genuinely to see the cats.
So, why isn't tourism industry developed on this island?
It seems that, in the past the island sought to attract tourists. According to an island map probably made in the 1980s, there were some campgrounds on the island. The tourists depicted on the map are bathing and fishing in the beach, The closed elementary school building was used for accommodation for tourists.
The Aoshima guide map, 20th century
But the tourism was not so successful that the accommodation was closed. In the 21st century, when the island became famous as a cat island, the island was not in a state to welcome the increasing number of tourists. In 2015 the city office made a suggestion to the islanders that the island be developed to welcome more tourists by building resting places and selling cat merchandise, but it was objected by most of the islanders. The islanders, at the age of 50s to 80s, have no desire to make money; they just want to live calm lives (*5).
Thus, tourism industry is not developed on this island. We cannot help wondering whether that was the right decision admitted also by the cats who are now the majority of the denizens on this island. Don't the moggies welcome more tourists? If there are more tourists, more lap cats may sit on the tourists' laps.
Not all cats can be on tourists' laps.
Some activists may advocate that cats should be endowed with what we call suffrage. This may be somewhat too radical an idea, but it would be a moot point. To what extent do we consider the well-being of cats? Until when can we make every decision for the sake of human-beings without considering feline welfare on this island where cats outnumber humans seven to one?
The human being, dominant species on the Aoshima Island in the 20th century, is not dominant in the 21st century.
There is nothing sustainable on this island; we might have no perpetually right answer to the question. But, anyway, the future will tell whether it would have been better for the tranquility of the Aoshima Island if neither cats nor tourists had ever existed.
(*1) 野澤 謙,「ネコの毛並み」 1996
(*2) Gingers are the top cats for owners but tabbies are too temperamental, 2012
(*3) John Bradshaw, Cat sense, 2013
(*4) The ferry shuttles twice a day. Each shuttle carries 34 passengers, but since there is no accommodation on the island, all passengers have to leave the island on either shuttle. Most of the tourists going to the island by the first shuttle return to Iyo-Nagahama by the second shuttle, so the number of passengers to go to the island by the second shuttle is limited owing to the number of the passengers left on the island.
(*5) 瀬戸内みなみ 「にっぽん猫島紀行」 2017
The history of the Aoshima Island began as late as in 1639 when a fishermen family discovered sardine fishery nearby and settled on the then uninhabited island. Thereafter, the population increased and peaked at 889 in 1942, then decreased to 102 in 1984, and 16 in 2012.
As the human population decreased, the feline population increased. In the 2000s, when the human population deceased to less than fifty, the feline population began to rise. In 2015 the human population was 16, while the feline apparently was 120.
The feline population, therefore, surged just in a decade in the beginning of the 21st century. What happened in that decade? Considering that almost no human beings have immigrated to the island in that period of time, it is highly likely that very small number of, if any, felines have immigrated. So, the feline population growth probably was caused by cats' reproductions under poorly controlled conditions, in which, cats had momentum to outnumber humans.
What we see today on the Aoshima Island, therefore, is the result of the rapid population growth on a genetically isolated land; that is the 'ginger explosion'.
Many cats on the Aoshima Island wear orange coats.
But are there really significantly many orange cats on the Aoshima Island compared to the mainland? If so, what is the proportion of orange cats?
What makes a cat a ginger, called a red mackerel tabby, is an orange gene (O) which is dominant to its allele, a non-orange gene (o). The orange gene exists only on X chromosome. So a ginger Tom, who has only one X chromosome, has one orange gene (Oy), while a female cat has either one (Oo) or two (OO). A female cat having two orange genes, or a homozygous genotype (OO), is a ginger queen. A female having only one orange gene, or a heterozygous genotype (Oo), wears orange and black mixed coat, which is called tortoiseshell. If a tortoiseshell cat has a piebald gene which makes a part of the coat white, she is a tricolor cat, which is called calico.
A ginger tom has an orange gene (Oy). A ginger queen has a homozygous genotype (OO).
A tortoiseshell queen has a heterozygous orange genotype (Oo).
A calico queen also has a heterozygous orange genotype (Oo).
A non-orange tom has a recessive gene (oy). A non-orange queen has a recessive homozygous genotype (oo).
Firstly we surveyed the cats' coat colors.
Cat coat colors on the Aoshima Island
Then we classified them according to orange genotype. On the premise that the sex ratio is 1:1, frequency of each genotype is uniquely determined.
Orange genotype of cats on the Aoshima Island
From this classification, the frequency of orange gene (O) works out to be 56 per cent. According to the zoologist Ken Nozawa, who conducted a comprehensive survey of cat genetics in Japan from 1975 to 1989, the orange gene (O) frequency in Japan was 31 per cent (*1). The frequency probably has not changed much since then, so, the Aoshima cats' orange gene frequency is significantly large.
So, why do so many the Aoshima cats have orange genes?
There are two possible scenarios; the first one is that the majority of the cats on the Aoshima Island incidentally had orange genes already in the 20th century before the population grew. If the frequency of the orange gene in the offspring was high, the frequency in their descendants would also be high. It is called founder effect, in which, a small number of individuals who migrate to a new land determine the genetic variation of their offspring on the land.
The second scenario is that orange cats would have been more adapted to the environment of the island and successfully outnumbered its allele. But there seems to have been no remarkable feature of the environment on this island but that cat-loving tourists have come to the island since the Aoshima Island became famous as a cat island.
If cats live on food given by tourists, their friendliness would make survival sense. According to a research conducted in 2012, ginger moggies are perceived by their owners as friendly and lovable (*2),
Are you friendly because you are a ginger?
But as far as we have seen a lot of friendly cats wearing various color coats on other cat islands, we do not say that orange cats are distinctively friendly with humans.
Not only gingers but also brown mackerel tabbies are friendly with tourists.
What is certain is that, on the Aoshima Island, compared with on the mainlands, many cats are unafraid of humans. They seem pleased to interact with every tourist.
This cat is so friendly that she comes so close to the camera that her image is extremely blurred.
So, why are the cats on the Aoshima Island so friendly with tourists?
One of the possible reasons is that, on this island, kittens have many chances to interact with various types of humans. Among the tourists are men and women, old and young. Unlike a household pet cat who interacts only with his or her owner, kittens on the Aoshima Island can interact with various types of human beings.
Not only adult cats but also kittens are friendly with tourists.
Cat experts say that whether a cat can be socialized with humans depends on when he or she begins interacting with humans. According to the research conducted in the 1980s, kittens handled by humans from their third week were happy to sit on a human's lap, but those whose contact with humans had been delayed to seven weeks jumped off a human's lap within half a minute. Kittens who had not been handled by humans during their first fourteen weeks stayed put for less than fifteen seconds (*3).
So what about the cats on the Aoshima Island? By measuring how long a cat sits on a human's lap, we may estimate how early he or she has begun interacting with humans.
11:23:40 A black mackerel tabby gets on a tourist's lap.
11:27:52 In four minutes the cat begins to purr, then snore, while another cat comes and grooms him.
11:43:32 He turns clockwise to be more stable.
12:41:06 Finding a stable position, he stays put for more than 30 minutes.
What we figured out is that, on this island it is not a cat's friendliness but a human's patience that determines how long the cat sits on the human's lap. The mackerel tabby got off the researcher's lap not because he wanted to do so but the researcher gave up measuring an accurate time of the cat's sitting on his lap. The researcher had been exhausted when he had kept the cat on his lap for no less than 70 minutes. If the researcher was more patient, the mackerel tabby probably have been on the researcher's lap for additional 60 minutes or perhaps even longer. Now that we do not know how long a cat sits on a human's lap, it would be difficult to estimate how early in his life he began interacting with humans.
The mackerel tabby, however, probably had opportunities of interacting with unfamiliar people in his very young days, and that is also the case of many other cats who have almost no fear of humans. We see today on this island several lap cats.
There are several cat islands in Japan, but there is no island on which so many cats like to be on tourists' laps as on the Aoshima Island.
Why do they like to contact with tourists? On of the probable reasons would be that on this island tourists are all cat enthusiasts. Compared with other cat island, the Aoshima Island is difficult to get to. The ferry shuttling between Iyo-Nagahama on the mainland and the Aoshima Island is small and shuttles only twice a day. The number of tourists a day is limited to from 34 to 68 (*4). So in holiday seasons the ferry is possibly full and some tourists cannot board and have to abandon the journey or try it another day. What discourages tourists furthermore is that the ferry is cancelled frequently in winter. During a stormy season the ferry service is cancelled once in three days. In a bad weather, a cancellation lasts seven to ten consecutive days.
The morning ferry leaves Iyo-Nagahama at 8:00 and arrives at the Aoshima Island at 8:35. It stays at the Aoshima only 10 minutes, leaving the island at 8:45; almost all the tourists go back to the mainland by the afternoon ferry which leaves the Aoshima at 16:15. Their sojourn, therefore, extends to seven hours and forty minutes.
What do the tourists do in such long hours? On this island there are no accommodations available, no restaurants, no shops, no casinos, no spas. During their sojourn, the tourists take photos of cats, feed cats, and play with cats. There is no tourist attraction on this island but cats.
A tourist on the Aoshima Island can readily take photos of beautiful pawpads.
Feeding cats is allowed in a designated place near the community center.
Cats on the Aoshima Island like playing with tourists.
Tourists on this island, therefore, are all more or less enthusiastic feline fanciers. They know well how to interact with cats; they don't do what cats dislike and allow cats to do what the cats like to do.
The cats on this island likely trust tourists coming all the way genuinely to see the cats.
So, why isn't tourism industry developed on this island?
It seems that, in the past the island sought to attract tourists. According to an island map probably made in the 1980s, there were some campgrounds on the island. The tourists depicted on the map are bathing and fishing in the beach, The closed elementary school building was used for accommodation for tourists.
The Aoshima guide map, 20th century
But the tourism was not so successful that the accommodation was closed. In the 21st century, when the island became famous as a cat island, the island was not in a state to welcome the increasing number of tourists. In 2015 the city office made a suggestion to the islanders that the island be developed to welcome more tourists by building resting places and selling cat merchandise, but it was objected by most of the islanders. The islanders, at the age of 50s to 80s, have no desire to make money; they just want to live calm lives (*5).
Thus, tourism industry is not developed on this island. We cannot help wondering whether that was the right decision admitted also by the cats who are now the majority of the denizens on this island. Don't the moggies welcome more tourists? If there are more tourists, more lap cats may sit on the tourists' laps.
Not all cats can be on tourists' laps.
Some activists may advocate that cats should be endowed with what we call suffrage. This may be somewhat too radical an idea, but it would be a moot point. To what extent do we consider the well-being of cats? Until when can we make every decision for the sake of human-beings without considering feline welfare on this island where cats outnumber humans seven to one?
The human being, dominant species on the Aoshima Island in the 20th century, is not dominant in the 21st century.
There is nothing sustainable on this island; we might have no perpetually right answer to the question. But, anyway, the future will tell whether it would have been better for the tranquility of the Aoshima Island if neither cats nor tourists had ever existed.
(*1) 野澤 謙,「ネコの毛並み」 1996
(*2) Gingers are the top cats for owners but tabbies are too temperamental, 2012
(*3) John Bradshaw, Cat sense, 2013
(*4) The ferry shuttles twice a day. Each shuttle carries 34 passengers, but since there is no accommodation on the island, all passengers have to leave the island on either shuttle. Most of the tourists going to the island by the first shuttle return to Iyo-Nagahama by the second shuttle, so the number of passengers to go to the island by the second shuttle is limited owing to the number of the passengers left on the island.
(*5) 瀬戸内みなみ 「にっぽん猫島紀行」 2017
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