Monday, December 23, 2013

Twelve Days Of Christmas – Biology Style

Biology concepts – introduced species, cross breeding, courtship rituals

We are finishing a long series stories on sleep and activity patterns, but I thought we might take a break and talk about the holidays. How about a couple of posts concerning the ways Christmas can be viewed biologically? We will return to activity patterns and Hawaii after the new year.

Lets examine the carol, “The Twelve Days Of Christmas.” Initially published in England in 1780, it was probably a British memory game before it was a carol, but older versions in France suggest that it came from that country originally. The twelve days of the lyric are from Christmas Day to the Epiphany (the baptism of Jesus of Nazareth).

Many interpretations of the song exist, from the devoutly religious to the idea of managing a country estate. For our purposes, lets stick to biological explanations of the gifts. Keep in mind that they were given by one’s true love; many have to do with family, love, and faithfulness – sounds more like a warning than a gift to me.

There are four subspecies of red-
legged partridge: French, Spanish,
southern Spanish, and Coriscan.
The English version is the Corsican,
even though it was imported from
A partridge in a pear tree – A partridge is a small game bird, a member of the pheasant family. The red-legged partridge is an introduced species; it was brought to England from France in the 1600’s as target practice for Charles II. The red-legged partridge is known to roost in orchards, including pear trees - hence the pairing of the gifts.

This bird is exceptional in that it often lays eggs in two different places. The female incubates one clutch while the male incubates the other. Their loyalty, devotion to family, and fidelity are plausible reasons for their inclusion in the song. This is further supported by another behavior of the female partridge. She will feign injury to draw the attention of a predator and protect her babies.

Two turtle doves – These members of the dove family are also a symbol of devoted love, since the males and females were imagined to mate for life. This turns out not to be true, as a study in 2008 shows that the hens will mate with bachelor males as well as males from other bird species. These hybrid crosses in other animals often result in non-fertile offspring (like mules, which are crosses between horses and donkeys), but the offspring of dove crosses are often fertile.

The Crevecoeur chicken is much like
the Houdan, but the Crevecoeur only
has four toes!
Three French hens – This might refer to cross-bred chickens. In the 1600’s, chickens were brought to France from the East and bred with French poultry. The Crevecoeur (named for the town in Normandy) breed is probably related to the Polish breeds. The very ornamental Crevecour is now only bred for poultry shows and is not eaten. Two other french breeds (three total) also originated around this same time, perhaps this is why they were used for the third gift.

Some believe that the chickens were included in the song because a rooster crowed at the birth of the baby Jesus. So shouldn’t the gift in the song be three French roosters? More likely it was because the hen represented motherly devotion and love.

Four calling birds –History suggests that calling birds was actually “collie birds,” another name for blackbirds (collie came from coal, as in coal-y = black like coal). The blackbird is a true thrush, common to most of western Europe. These were fairly common birds in the 1700’s, and were trapped in barns and the like to supplement the diet. They became a delicacy.

While the first four gifts all refer to birds, only the first three bring connotations of love and fidelity. The fourth is mostly commonly associated with eating. Which of these things is not like the others?

The male pheasant has the golden rings. 
Does he give one to the plainer female during 
courtship? Male ornamentation is common 
in lower animals; in humans it looks silly, 
pinkie rings and a one earring.
Five golden rings – Maybe we were just starting a new pattern, since the five gold rings also refers to eating a bird. Golden pheasants have five or more golden rings on their necks, and they were often served at royal and other high society feasts.

Pheasants and partridges are closely related; they come from the same family of Phasinidae. While they are very different in size (about 7 inch quails to 30 inch pheasants), they both have short, powerful legs that allow they to run quickly along the ground to elude predators.

Giving your true love five gold rings is overkill anyway, right?

Six geese a-laying – Still with the birds - how is it that the Audubon Society hasn't adopted this song as their anthem? In the carol, the geese may serve two purposes. One, they were bred for better egg laying, up to 50 eggs per year. This made them symbols of fertility. Second, they were often served as Christmas dinner – remember the prize goose the reformed Scrooge purchased for the Cratchits.

The indigenous wild boar was originally the choice for Christmas feasting, but was hunted to extinction on the island by the 13th century. It was reintroduced later, but turned into a nuisance by eating all the crops. Consequently, it was hunted to extinction in England again by the late 1700’s. Imagine the kind of protests that would occur nowadays if a species was about to be eliminated for second time in the same place! Even today, a string of sausages is often placed around the goose’s neck as a reminder of boar’s place on the table.

The male (cob) and female (pen) swan will
mate for life. If one dies, the other will remain
alone for the rest of its life.
Seven swans a-swimming – Because swans could both swim and fly, they were revered in many ancient cultures. Waterfowl (Anatidae family, includes ducks, geese and swans) may have evolved from the galliformes (order including chickens and our friends the pheasants and partridges). This is the majority opinion, but some scientists believe that they descended from shorebirds. This is believable, they already lived on the shore; it was a short trip to adapt to the water.

King Edward used swans in his coronation in 1304, and other royal families then adopted their use across Europe. As such, all swans in public were the exclusive property of the monarch (landowners could have some on their property), and were seen as precious, just like the adoration of your true love. Oh, and they ate them at Christmas too. Apparently, during this time period, the way to another’s heart was through their stomach, and birding.

Personally, I think of Edward Jenner when 
milkmaids are mentioned. He recognized that
they didn’t get smallpox, only coxpox. He used
this knowledge to develop a smallpox vaccine.
Eight maids a-milking – The first seven gifts were all birds, but the last five gifts are all humans. Is that a step up or a step down? As for the milkmaids, we have two ideas implied; one is food, and the other is romance (or just lust).

In the 1700’s there was no refrigeration, so milk products were short-lived and therefore precious. Giving a loved the ability to have fresh milk would mean many holiday treats, like custards and cheeses. Food and banqueting are sure playing a big role in this song.

The other use of this gift is slightly less savory. In France, the milkmaid was a sign of fertility; big-busted and fit. In England, to ask a young lady to go a-milking could be a legitimate proposal of marriage, or an illicit proposal of hanky-panky. Either way you take it, this is a loaded gift, biologically-speaking.

Nine ladies dancing – The rest of the gifts have to do with musicians and dancers. Basically, the gift-giver was hiring a band and entertainment for his/her true love's banquet.

Dancing is often considered the human equivalent of sexual selection behavior in animals. Indeed, the psychologist Geoffrey Miller deduces that human culture of all types developed as a type of sexual selection, which, along with natural selection, forms the basis of evolution.

Is this a female or a male squinting bush
brown butterfly? What if I told you it has
been warm and rainy the past few weeks.
Females dancing as a courtship ritual is an exception. Usually males display and try to draw the attention of the female. However, in one species of cichlid fish, the striped kribensis, the females do dance for the males, brushing their large pelvic fins against the male. Males will most often select the females with larger pelvic fins.

Other species will have the females dance – sometimes. In the squinting bush brown butterfly, it all depends on the temperature when the caterpillars mature. If cool, then the females will develop large ornamental spots and will dance to attract males. If they mature in warmer, moist conditions, the males will have the spots and will dance for the females.

Ten lords a-leaping – The males of many species dance as a part of courtship. Jumping spiders have an elaborate dance that is meant to show off their iridescent hairs and bright abdomen. They also vibrate or twitch their abdomens and legs (click for a video link) to make a purring sound as well. Grebes (birds) have a mutual dance and run that the male and female perform together, both as part of initial mate selection, and then repeated to reinforce their bond (click for video).

In a positron emission tomographic (PET) image,
yellow and red mean more activity. Notice how words
(bottom left) and music (bottom right) seem to
activate different parts of the brain. Pleasant music
activates positive emotional centers.
Eleven pipers piping – Commonly, the pipers are shown to be playing flute or other recorder-type instruments, but I think that the bagpipes might be more accurate historically. The best biology I can do for the bagpipes is that they are supposedly a source of music, they are meant to generate positive emotions – music soothes the savage beast. PET scans confirm that dissonance in music activates the negative emotion centers of the brain. For me, the pipes are quite dissonant.

Twelve drummers drumming – This final gift may relate to the rhythm of the drums. Anthropologists talk about drumming in terms of emulating the beating heart.  This brings us back to romance and love, and in a sense, drums are then the truest form of biological music.

If we return to the banquet motif that has pervaded so much of the gift giving here, drums were late coming to England and Europe. They were teamed with the trumpets that would announce the arrival of the next course during the banquet. How could they possibly notice the next course with all those ladies dancing, lords leaping, and pipers piping, not to mention all the birds hanging around?

You probably didn’t realize there was so much biology in a Christmas song - but biology is everywhere. Next time we will investigate the biological aspects of a few random holiday traditions. For example, in many lizard species virgin births are no big deal.

All the concepts here will be explained in more detail in the near future, resources for each will accompany their explanations.

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