It’s easy to take oxygen for granted. But, let’s not for a moment.
Instead, imagine a sugar maple with its broad, green, leaves. Zoom in on a single leaf, rustling slightly in the breeze. Think of a cell within that leaf. Now we’re getting closer to the action. Dive a bit deeper and you will see that each leaf cell contains from 10-100 organelles called chloroplasts. Each chloroplast is enclosed by a membrane within which are several structures. One of those structures is called a thylakoid. We’re almost there. Within the thylakoid are hundreds of molecules of chlorophyll.
Chlorophyll. That’s where our oxygen comes from. This wondrous molecule is the driving force behind that essential process called photosynthesis.
There are several different types of chlorophyll, each with a slightly different structure. Chlorophyll a, for instance, is C55H72O5N4Mg, while Chlorophyll b, is C55H70O6N4Mg.
Photosynthesis plays three important roles.
1) It feeds the tree (or other plant) providing energy for it to live.
2) It “fixes” carbon, meaning it takes carbon dioxide, which is a greenhouse gas and uses that carbon in other ways, thereby reducing the amount of CO2 in the air.
3) It releases oxygen into the air as a waste product. In essence, trees and other plants (as well as algae and some bacteria) “inhale” CO2 and “exhale” oxygen, while we humans and other animals do the opposite.
In the most common form of photosynthesis, the chlorophyll in a tree’s foliage (our maple leaf, for instance) uses sunlight as the energy needed to transform carbon dioxide and water into simple sugars which fuel the tree’s growth and reproduction.
Chemically speaking “sugar” refers of a number of different carbohydrates generally made up of carbon, hydrogen and oxygen.
Carbohydrates are essential in living organisms. Among other things they are used to store energy, to form physical structures and are a component of both RNA and DNA. Carbohydrates also break down into fats and other less useful molecules, hence too much sugar is bad for your health.
When light hits a tree each molecule of chlorophyll absorbs one photon and the energy of that interaction knocks loose one electron. That electron passes to another molecule then another and another in a flow of electrons called an electron transport chain.
Through a rather complicated process (described in another post) this energy allows the carbon, hydrogen and oxygen molecules to rearrange themselves from carbon dioxide and water into a simple sugar. The chlorophyll molecule ultimately regains the electron when a water molecule (H2O) gives up its O (oxygen) as a waste product.
The general formula looks like this: 6 CO2 + 6 H20 + photons = C6H12O6 + 6 O2.
The energy for that transformation comes from the sun. Multiply that several trillion, trillion times and you have a perfectly nice maple tree as well as a delicious, oxygen rich, atmosphere for humans and other animals.
Stay well, be curious, learn things.
Thanks for reading,
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I remember kayaking on the Charles River near Boston. The river was narrow, and overhung with trees. Vines and bushes crowded the bank while dragonflies skimmed over the water. I went around a bend, startling a Great Blue Heron into flight. It gave a honking squawk as it beat its great wings and took off looking like a prehistoric beast come to life.
That’s not surprising, since herons are not far removed from prehistoric beasts. All birds, in fact, are direct descendants of dinosaurs, specifically a group of two legged dinosaurs called theropods (which includes the monster Tyrannosaurus rex as well as the velociraptors.) It’s hard to imagine that the Ruby Throated Hummingbird is related to T rex, but more and more evidence is being uncovered to show this link.
That leads to the question: what makes something a bird? Wings, feathers, and flight come to mind, none of which are necessarily associated with dinosaurs, but there are other commonalities between today’s birds and the dinosaurs of yesteryear.
Birds have a rapid metabolism, one that requires a lot of oxygen. To solve this they have evolved a highly efficient respiratory system. In humans and other mammals air is inhaled into the lungs where it crosses the lung membrane and enters the blood stream. As the blood circulates oxygen is removed from the blood stream and the depleted blood returns to the lungs for a fresh supply of oxygen. Meanwhile, the excess carbon dioxide is exhaled. This means that each inhale necessarily mixes fresh oxygen with the stale air already in the lungs. This isn’t the most efficient system, but it works. Birds streamline the process.
Birds inhale and exhale as we do, but the air doesn’t mix in their lungs. Rather there is a one-way system within their lungs which allows the fresh air to remain separate from the stale, ready-to-be-exhaled air. This system includes a number of air sacs which are integrated into the skeleton. These sacs help move the air allowing for the unidirectional flow.
This means that birds have continuous access to fresh oxygen, even while exhaling. The air sacs also help lighten the bones as well as provide a storage system for oxygen as it moves through the lungs and blood stream. This neat trick allows geese, hawks and other birds to fly at high altitudes where oxygen is scarce as well as to maintain the high metabolic rates of hummingbirds and other flitters and fliers. As stated in the article “Bird Respiratory System”:
“The avian pulmonary system uses “flow-through ventilation,” relying on a set of nine flexible air sacs that act like bellows to move air through the almost completely rigid lungs. Air sacs do not take part in the actual oxygen exchange, but do greatly enhance its efficiency and allow for the high metabolic rates found in birds. This system also keeps the volume of air in the lung nearly constant.”^1
According to WorldAtlas.com the mild mannered Mallard Duck can fly up to 21,000 feet (6,400 meters.) Granted that couldn’t get it over Mt Everest at 29,029 feet. Only two birds can manage that achievement. The Common crane has reached an altitude of 33,000 feet (10,000 meters). Sadly, the record holding high flying bird, the Ruppell’s Griffon Vulture is critically endangered. If we don’t protect it we will lose the highest flying bird on earth, a species that has been recorded flying at 37,000 feet (11,300 meters.) That is around the maximum altitude for commercial aircraft and higher than small planes can reach.^2
That’s a great trick, but what does it have to do with dinosaurs? Turns out that some dinosaurs had a similar system, complete with one way oxygen exchange and air sac interspersed within their skeletons.
Other evidence for the relation between birds and dinosaurs comes from the fact that dinosaurs evolved feathers before the began to fly. That means that feathers had an evolutionary purpose other than flying. Think about ostriches, penguins, emus and other flightless birds. They still retain feathers and wings. Penguins use feathers for insulation and waterproofing while their wings have evolved into flippers for “flying” through the water. Ostriches use their wings for display both for attracting mates and for defense. They also hold out their wings for balance while running. In other words, feathers have uses beyond flight. Dinosaurs probably used feathers for similar purposes before they became airborne.
What it all comes down to is an evolutionary line can be drawn directly from the theropod dinosaurs to modern birds. The next time you think a bird looks prehistoric pat yourself on the back for your cleverness.
Be well, stay curious, learn things.
Thanks for reading
Despite the quarantine, or perhaps because of it, I’ve been spending my summer making new friends. I’m embarrassed to say, that despite living among them for my entire life, I’m just now making their acquaintance. Please allow me to introduce them – I’m sure some of them, or perhaps their cousins, live near you as well.
Butterflies can be separated into families. This is fortunate for newbies like me, because butterflies are overwhelming. Some look so much alike I can’t even see the difference when staring at photos in a guidebook. Others look different to me but are the same species. It’s all very confusing.
First a disclaimer. I’m taking my information from a wonderful online class with Bryan Pfeiffer – a man who knows his butterflies and how to get students excited about them, as well as from various field guides, particularly A Swift Guide to Butterflies of North America by Jeffrey Glassberg. I’m checking my info, however, I am a newbie and any mistakes are my own.
We can start by breaking it down into 6 North American butterfly families. Actually, I’m only going to talk about 5, because one family – the Metalmarks, don’t fly near me. The ones I’m learning are:
Swallowtails, family Papilionidae. These are the easiest for me to identify. They are large and have “swallowtails.” Below is probably a Canadian Tiger Swallowtail, but possibly an Eastern Tiger Swallowtail, or even a hybrid. (Feel free to let me know in the “comments” below.)
Whites and Yellows and Sulphurs, family Peridae are the next family. They are identifiable by their color, which is usually, yes, white or yellow. But it can also be on the green side of things, or even pink edged, but they have a pale pastel look to them and the never stop flitting around!
Gossamerwings, family Lycaenidae, are difficult for me. To begin with there are a lot of them. They can be further divided into coppers, hairstreaks, blues and harvesters. My goal is to place them within their sub family. These are beautiful small creatures, with delicate lines and colors. They are easy to overlook, but I recommend spending time with them.
Brushfoots family Nymphalidae, are also tough. These butterflies include checkerspots, crescents, fritillaries, ladies, commas, admirals and others. No wonder it’s confusing. I try to identify it’s broader group – ah yes, that’s a comma and over there is probably a crescent. But really… Fortunately many of them like to pose for the camera.
Here are a few of the more obvious.
Then comes my favorite group. The Skippers, family Hesperiidae. I’m not sure what it is I like about these little dudes and dudettes, but they are cute. They are small and fly around like the busiest of bees. Unless they have strong markings I don’t bother trying to identify them, I just enjoy their presence.
Here are a few additional for you to test your identifications skills. (Good luck.)
This doe is out of control. Once again she has terrorized my poor pup.
I was sitting in my back yard when Beatle started barking. Sure enough the doe was back. You can see one of our previous encounters (we’ve had several) here.
In the photo below you can see here just how close she was. I was glad to have the fence between us. I had to wave a shirt at her while yelling at her to “git,” before she “got.” Even then she ran off a few yards and returned twice before she got bored with harassing us and trotted off to find better victims.
Last week I saw her chase our neighbor’s cat. (I’m not kidding. This really happened.) My sister and I were standing on the front steps (at a proper social distance) and the cat came tearing down the road at a dead run.
Coyote or fox after him? Neighbor’s dog on the prowl? Nope. Two seconds later who appeared but the devil in disguise. That damn doe, charging after. I have heard of deer chasing animals to protect their fawn, but this is beyond the pale.
I have decided this doe must be a demon.She pretends to be a deer in order to lure her prey closer. But look how she bares her teeth when she thinks no one is looking.
In fact, if you look closely, you can see her fangs.
It’s been a busy morning, full of unexpected company.
It began as I took my dog for a walk along a nearby back road. I had just stopped to say hello to a butterfly, when I notice a red fox up ahead. Fortunately, I saw it before my dog, so by the time she threw herself to the end of the leash barking hysterically I was ready.
We had just recovered from that when a fawn spooked out of the meadow. Perhaps by the fox which had headed that way. It’s amazing to watch deer run. They leap, float and rebound so gracefully it seems they are barely moving. However, it didn’t take long for the fawn to disappear.
I decided to concede the road to the wildlife and hustled my dog back home. Since we hadn’t had much of a walk we proceed to circle the yard. When the wild turkey flushed under my feet I confess I yelled.
It was not a peaceful morning.
I left the dog inside and headed back to the dirt road. There I spent an enjoyable hour making friends with a butterfly. Perhaps the same one I had stopped for recently.
Thanks for reading. Stay well, be curious, learn things.
In the early 1800’s Charles Dickens was born, Jane Austin was in the middle of her career, and a young girl named Mary Anning was about to unearth a fossil.
Mary Anning was born in 1799, to a poor family living in the coastal town of Lyme Regis in Dorset, England. Her father, Richard, was a cabinetmaker who supplemented the meager family income by selling fossils, or “curiosities” to tourists. Richard must have adored his daughter, because from the age of 5 or 6 Mary joined him on his fossil hunting expeditions to the cliffs nearby, despite how unusual this would have been at the time. Unfortunately, when Mary was just 11 years old, her father died leaving the family finances yet more precarious.
Soon after their father’s death, Mary’s brother Joseph, was out searching for fossils when he found a 4 foot long skull of what he took to be a gigantic alligator. He took it back to the house as an interesting, but not particularly important, find. Joseph soon took up an apprenticeship to help earn money for the family, challenging Mary to find the remainder of the skeleton. She took up the challenge. Almost a year later 12 year old Mary found the remaining bones of the “alligator.”
Imagine the scene, a young girl, in worn, hand-spun clothing, tapping at the rock face with a pick and chisel, carefully carving away the eons of materials encasing the bone fragments. Over the course of several months she unearthed the entire skeleton of what was clearly not an alligator. It was so large she needed the help of several of the village men to bring it to her home. She recognized the importance of the find and carefully cleaned and mounted the specimen. When news of the find spread a collector came to view, and eventually purchase, the skeleton. A few years later it was recognized as a new creature and was named Ichthyosaurus.
This was just the beginning for Mary. Over the course of her lifetime she unearthed any number of fossils, including the first full skeleton of a Plesiosaurus giganteus, a new fossil fish species (Squaloraja,) and a new type of pterodactyl. She gained a reputation for her ability, not just to find fossils, but for her knowledge of the anatomy of the different species. She was also fastidious about cleaning, mounting and framing the specimens. She took meticulous notes and made drawings of her finds which she used to tempt collectors and inform her friends.
This was an age when science and religion were fighting over the origin of the earth. According to the Bible (and prominent theologians) the earth was approximately 4000 years old and had remained as it was created. However, there were some problems with this theory.
Mary’s fossils were part of the problem. How to explain these bones? Where did these monsters come from? Why had no one ever seen one before? Presumably a creature as large as some that she and others were finding would have caught someone’s attention at some point in history. Was it possible these animals no longer existed? It was at this time that the debate about evolution was heating up and fossils became a part of the argument in favor of a changing world. According to her journals and letters Mary wasn’t interested in the philosophical debate, but rather was fascinated by the creatures themselves. She read what she could and corresponded with many prominent scientists of the day.
Although she remained poor, Mary eventually earned enough to open a small shop at the front of the house she lived in with her mother. There she met many of the men, and the few women, studying the new science of paleontology. She often became friends and corresponded with them over the years including with Henry De La Beche, Louis Agassiz, Richard Owen, and The Philpot sisters: Mary, Elizabeth and Margaret. Elizabeth in particular became a close friend and the two of them would scour the cliffs together, sharing the excitement of each new find.
Mary took her friends and many others on tours of the cliffs or brought them out to hunt fossils with her. She was generous with her time and skill, despite the fact that her clients and friends were mostly wealthy, while she barely managed to scrape by. In fact, in 1821, a collector friend named James Birch stopped by to discover that the family was on the verge of selling their furniture to pay the rent. Birch was so horrified by their plight he sold his own collection to raise money for them:
The fact is I am going to sell my collection for the benefit of the poor woman Molly and her son Joseph and daughter Mary at Lyme who have in truth found almost all the fine things, which have been submitted to scientific investigation.^1
Over time, many of Mary’s male friends became leaders in the field. However, while they received recognition for their work, Mary remained mostly unacknowledged. As a poor woman she was invisible to the establishment, despite the number of specimens she had contributed to that establishment.
Women were not accepted into the scientific societies which benefited from her work and Mary was rarely given credit, even by her friends. However, after she died of breast cancer in 1847, at the age of 48, the president of the Geological Society of London, her friend Henry De la Beche, gave the following eulogy:
I cannot close this notice of our losses by death without advertising to that of one who though not placed among even the easier classes of society, but one who had to earn her daily bread by her labor, yet contributed by her talent and untiring researches in no small degree to our knowledge of the great Enalio-Saurians, [ichthyosaurs and plesiosaurs] and other forms of organic life entombed in the vicinity of Lyne Regis…there are those among us in this room who know well how to appreciate the skill she employed (from her knowledge of the various works as they appeared on the subject) in developing the remains of the many fine skeletons of Ichthyosouri and Plesiosauri, which without her care would never have been presented to the comparative anatomist in the uninjured state so desirable for their examination…. ^
It was not until the 20th Century that scientific societies began to accept women as full members and even today women are often not recognized for the work they do. Once the contributions of all members of society come to be recognized people like Mary Anning will finally be acknowledged for the contributions they have made.
1 Hugh Torrens, “Mary Anning’s Life and Times: New Perspectives,” Mary Anning Symposium, 1999; Lyme Regis, June 2-4, 1999. As quoted in: The Fossil Hunter: Dinosaurs, Evolution and the Woman Whose Discoveries Changed the World, by Shelley Emling, Palgrave McMillan, 2009. p.71.
Ibid p. 199-200.
Thanks for reading. Stay well, be curious, learn things.
The idea of race was formally introduced to Europe by an adventurer and traveler named Francois Bernier (1625-1688.) In 1684, after traveling around the world, he published a work called A New Division of the Earth. In it he proposed that humanity could be divided into “four or five species or races of men in particular whose difference is so remarkable that it may be properly made use of as the foundation for a new division of the earth.” Thus began white racism.
Bernier’s division was based on looks and geography. He listed race according to specific countries, going so far as to separate out specific areas within countries for one race or another. This question of the division of humanity into races was controversial, not because it was arbitrary and bigoted (which it was,) but rather because it raised the question of whether all of humanity was a single race descended from Eve (called monogenesis,) or whether the different races were actually different species (polygenesis.)
This was a time of change in Europe as previously unquestioned beliefs about the world were challenged by science. In particular, the new field of paleontology (the study of fossils) played a large role in the growing belief in some form of evolution. The theory of evolution was solidified by Charles Darwin who showed how all humans could be traced back to a common ancestor. While there remained a few stubborn hold-outs, Darwin refuted the idea of polygenesis. But the idea of race as a way of categorizing people remained. One of the reasons for this was a need to justify slavery.
Slavery has existed as long as human civilizations have existed. However, slavery in earlier times was usually situational. By that I mean that people were conquered or kidnapped and forced to work for their captors. People were sometimes legally enslaved as a punishment, or because of debt. In some cultures children of enslaved mothers were born into bondage. Differences in religion or language were often viewed with suspicion and sometimes slavery was allowed for one group and not another. People were bought and sold. These forms of slavery were often brutal and the enslaved were often dehumanized.
Something shifted, however, with colonization and the international slave trade. Suddenly slavery was big business. Big, international business. As colonization divided Africa between European states African people became a commodity. Not only did this reduce resistance to European conquerors, but enslaved Africans provided labor for the growing plantations. It’s one thing to say we captured your village and now you have to work for us and a whole different thing to say you are now a cog in a business enterprise. That requires a different level of dehumanization.
Here the idea of race comes in handy. If you can group people into specific categories it becomes easier to form nice neat hierarchies. Now it becomes possible to say “my race is better than yours.” As science gained traction it was used to justify the hierarchy among races. In 1775 Johann Friedrich Blumenbach used skull size to “prove” that whites were superior to all others. (It wasn’t until the late 1800’s-early 1900’s that Franz Boas challenged this by showing that nutrition was actually the cause of the variation. He showed how children of immigrants had skulls similar to their country of birth – as did their parents.)
In the 19th and 20th Centuries people used pseudoscience to justify eugenics, the idea that by breeding together the “right” types of people you could create a superior human. In the US this was used to create a hierarchy among immigrants of different races. Among the many problems with their “science” was the use of undefined and subjective terms such as “feeble-minded,” “degenerate” and “criminal type.” Researchers applied these terms to their “subjects” based on their own determination rather than any set measures. If they felt someone was feeble-minded that was the label given to that person. This of course reinforced the biases of the eugenicists as they set out to determine who was the smartest, strongest and most desirable type of person.
They discovered, surprise, surprise, that people just like them were the superior human race. The eugenics movement lost favor after Nazi Germany took it to the extreme, although the idea of race still remains entrenched in our society. Now though, it’s less certain what is meant by race.
Modern science has studied race using DNA and found that, overall people are more similar than different. There are certainly genetic differences between people and also between groups of people. But divvying people up into specific groups is harder. People move around and cultures mingle. That means that you can’t say this area is defined this way, because it will depend on the era. At one point in time that area may have been dominated by group A, while a few centuries later group B migrated from area C and the people are now genetically ABC people. We all originated in Africa. After that it gets messy.
Then there is the problem that this does not say anything about race. It is necessary to first define what is meant by race. Clearly race exists and plays a big role in our society, but it is a cultural construct. Just as being Canadian, or a Vermonter is “real,” so race is real. However, it is a socially defined label, not a scientific division. And certainly not a reason for discrimination.
We can only hope that the Black Lives Matter movement continues the slowly growing cultural perception that race does not describe a hierarchy. It does not describe a scientific division among people. Race exists. We shouldn’t strive for sameness, but rather for equal enthusiasm for the rights of all races. That will require us white folk to give up on the idea of racial superiority which is so ingrained into our culture as to be invisible. Until we look hard at the history of the white race it will be impossible to see ourselves as one race among many – however society decides to define it.
Stay well, be curious, learn things. Kate June 2020
Note: François Bernier, “A New Division of the Earth” From Journal des Scavans, April 24, 1684. Translated by T Bendyshe in Memoirs Read Before the Anthropological Society of London, vol. 1, 1863-64, pp.360-64.