Speaker 1: Welcome to Stuff You Missed in History Class, a production
Speaker 1: of I Heart Radio. Hello, and welcome to the podcast.
Speaker 1: I'm Holly Fry, and I'm Tracy Vie Wilson. Tracy, I
Speaker 1: bet this happened to you. I know it happened to me.
Speaker 1: Like you must have had those moments as a child
Speaker 1: where you thought you were being very insightful. I know
Speaker 1: I certainly did where I was like, how do I
Speaker 1: know that what I see is the same thing as
Speaker 1: other people see? I had this exact Yes. Yes, I
Speaker 1: also asked my mom one time. I was like, Mom,
Speaker 1: how do how do we know that what I see
Speaker 1: as green is the same thing as what you see
Speaker 1: as green? Uh? And my mom, stay at home mom
Speaker 1: with two little children, did not always have a lot
Speaker 1: of patients for weird questions. And she was like, it's
Speaker 1: the same. I'm not trying to drag my mom in
Speaker 1: any way. I'm know of our creativity and attentive to
Speaker 1: our but yeah, this was a case where I liked
Speaker 1: I just asked her a question she was not prepared
Speaker 1: for question time. Here is the thing. I asked the
Speaker 1: same question of my father, who I did not know,
Speaker 1: and I don't know that he knew at the time
Speaker 1: did not see color the way, so so he was
Speaker 1: trying to describe things, and I just remember, I mean,
Speaker 1: I was probably like seven or eight, already kind of
Speaker 1: a smart alic, and I was just like, okay, this
Speaker 1: is going nowhere. I'm out. So maybe just saying green
Speaker 1: is green was a really a better route because that
Speaker 1: led to a lot of confusion in our lives, um
Speaker 1: for a moment, until we finally put the pieces together right.
Speaker 1: And really what happened was that. And I don't mean
Speaker 1: to drag my father, but like he was career military,
Speaker 1: so um, he's now retired, but his clothes were like
Speaker 1: sort of prescribed for sure. When he stopped up being
Speaker 1: constantly on active duty and started picking out his own clothes,
Speaker 1: some things became readily apparent, which is that that does
Speaker 1: not go together. My dude, Yes, they look they're practically
Speaker 1: the same color. Oh, we should address this, right. That's
Speaker 1: we never knew for years, when you're wearing like jeans
Speaker 1: and a plaid shirt in your off time and then
Speaker 1: a uniform the rest of the time, it would never
Speaker 1: come up. Now we learned. But this curiosity about whether
Speaker 1: other people see the way that you see is really
Speaker 1: what drives a lot of scientific discovery. Uh And we
Speaker 1: are talking about somebody who was curious and did a
Speaker 1: lot of scientific discovery. But in the case of this subject,
Speaker 1: who was very well known and respected in his day,
Speaker 1: he just didn't think about how he or anyone else
Speaker 1: saw color until he kind of stumbled into it while
Speaker 1: studying plants and realizing that his vision might be different
Speaker 1: from other people. And that's John Dalton. And really John
Speaker 1: Dalton is far more famous for his work in atomic
Speaker 1: theory and which builds the foundations of organic chemistry, but
Speaker 1: he also wrote one of the first really thorough descriptions
Speaker 1: of what he called anomalous vision, meaning that he realized
Speaker 1: he was not perceiving color in the same way as
Speaker 1: other people. And his descriptions are very entertaining. We're going
Speaker 1: to read some of them. Uh So today we will
Speaker 1: talk a little bit about his life, but mostly about
Speaker 1: this sort of pocket in his scientific work, where he
Speaker 1: made a brief foray into exploring the world of photoreceptors
Speaker 1: and color perception, although he didn't use those words for it.
Speaker 1: Color blindness is a term that's falling out of favor
Speaker 1: because it's not really accurate color blind suggests that somebody
Speaker 1: can't see color at all. But most people who have
Speaker 1: historically been diagnosed with color blindness can see colors, they
Speaker 1: just see them differently. So defective color vision or color
Speaker 1: vision deficiency are becoming more preferred terms. I feel like
Speaker 1: I see people describing them selves as color blind still
Speaker 1: quite a lot, So this is something that's evolving. We're
Speaker 1: still kind of at the beginning of the scientific community
Speaker 1: shifting to these different terms just and it's really about
Speaker 1: clarity more than anything else, right, Like, now you do
Speaker 1: see color. We'll talk about one exception, but just differently.
Speaker 1: So we need to make a clearer term for it
Speaker 1: that's not misleading. And color vision deficiency is the inability
Speaker 1: to distinguish specific colors red, green, and blue, and to
Speaker 1: be diagnosed as color blind historically or color vision deficient. Now,
Speaker 1: a person only needs to have an inability to distinguish
Speaker 1: one of these colors, but it is possible for someone
Speaker 1: who has color vision deficiency to be unable to distinguish
Speaker 1: all three. So in your retina, you have cells called rods,
Speaker 1: which perceive light, and then three types of cells called cones.
Speaker 1: Cones are really the important factor. Here. They are the
Speaker 1: photoreceptive cells that enable us to perceive color. The human
Speaker 1: retina contains six million cones. Red sensing cones make up
Speaker 1: sixty of the total number of cone cells, green sensing
Speaker 1: cones make up and blue sensing tones make up the
Speaker 1: remaining ten. So if all of your cone cells are
Speaker 1: functioning normally, you are said to have trichromacy, meaning you
Speaker 1: can see three try of these colors and they combine
Speaker 1: to create standard vision. But it is also possible to
Speaker 1: have dichromacy with only two types of cone cells present
Speaker 1: or functioning, or even monochromacy where only one type of
Speaker 1: cone is functioning. Monochromacy is a little bit tricky because
Speaker 1: it can also be used to describe a scenario where
Speaker 1: none of a person's cones are functioning, and a person
Speaker 1: who has monochromacy may have other vision issues as well,
Speaker 1: And monochromacy that we just talked about with no cone
Speaker 1: function is kind of the one variation in all of
Speaker 1: this where the color blind label would be actually pretty accurate,
Speaker 1: because everything to them appears not in the rainbow of colors,
Speaker 1: but as a shade of gray most of the time.
Speaker 1: Dichromacy manifests itself in a way that a person can't
Speaker 1: see a difference between red and green, and dichromacy of
Speaker 1: this nature is broken down into separate classifications based on
Speaker 1: which types of cones do and don't work in a
Speaker 1: person's retina. Protnopia describes a state of not being able
Speaker 1: to see red, and due to anopia is a case
Speaker 1: where the red cones functioned but the green cones do not.
Speaker 1: Blue yellow color deficiency, which is a little rarer, is
Speaker 1: similarly broken down into classifications based on its specific nature
Speaker 1: in a given person. So someone with a lack of
Speaker 1: blue cones is said to have tritenopia, and if they
Speaker 1: have blue cones but reduced sensitivity to that color, it
Speaker 1: is actually described as trite Anomally, and all color vision
Speaker 1: deficiency can fall on a spectrum. Some people have a
Speaker 1: diminished ability to distinguish red from green, for example, but
Speaker 1: they're able to see difference then specific shades of these colors. Yeah,
Speaker 1: sometimes you know, people can't hit the lighter tones of
Speaker 1: the darker tones get real muddy, but they can see
Speaker 1: different shades. It's it's all. It manifests in many different
Speaker 1: ways and in the United States and estimated five to
Speaker 1: ten of the population have some form of color vision deficiency.
Speaker 1: Usually this gets tested for when people are kids, and
Speaker 1: more boys than girls have colored vision deficiency, and the
Speaker 1: percentage shifts based on race. So there was a twenty
Speaker 1: fourteen study that gets cited a lot uh. This was
Speaker 1: published in the journal Optimology, and it had taken studies
Speaker 1: of the color vision of four thousand California children ranging
Speaker 1: in age from three to six. And in this study
Speaker 1: it was found that among the girls, less than half
Speaker 1: a percent of them exhibited signs of color vision deficiency
Speaker 1: regardless of race, but in boys the numbers were different.
Speaker 1: Six percent of the white boys in the study were
Speaker 1: diagnosed with color vision deficiency, three percent of the Asian
Speaker 1: boy had some form of color vision deficiency. It was
Speaker 1: found in fewer than three percent of the Latino boys
Speaker 1: and less than two percent of black boys. Genetically, boys
Speaker 1: are more likely to have red green color vision deficiency
Speaker 1: because they only need to inherit it from their mother.
Speaker 1: It is a recessive characteristic that's associated with the X chromosome.
Speaker 1: So if a female inherits the trait from her mother
Speaker 1: but not her father, she'll generally have normal color vision.
Speaker 1: She only has that one X chromosome, but then she
Speaker 1: could pass a trait onto her own children. And this
Speaker 1: is different from blue yellow color vision deficiency, which is
Speaker 1: a dominant characteristic, and so that only needs to be
Speaker 1: inherited from one parent, and it is not linked to
Speaker 1: a person's sex. I'm just gonna say these are related
Speaker 1: to sex and not to gender. That's the different thing. Yeah,
Speaker 1: we're going with kind of that twenty fourteen studies separation
Speaker 1: of boys and girls, which simplifies the whole discussion, and
Speaker 1: is sex assigned at birth not necessarily? How if they
Speaker 1: did that, I would be fascinated if they did the
Speaker 1: same exact test today and how they would break it out,
Speaker 1: because it's things have shifted a bit um. So if
Speaker 1: anybody knows of any studies similar to that going on today,
Speaker 1: I'm very curious. But here's the thing. You're probably wondering,
Speaker 1: how we figured all of this out? Uh. And in
Speaker 1: the late eighteenth century, this idea of people perceiving color
Speaker 1: differently than most humans was certainly not unknown. King George
Speaker 1: the Third, for example, reportedly discussed this with an English novelist,
Speaker 1: Fannie Bernie at court in seventeen eighty five, and there
Speaker 1: were some theories about what caused color vision anomalies published
Speaker 1: in Germany in the late seventeen hundreds, but the first
Speaker 1: systematic analysis of color vision deficiency appears in seventeen at
Speaker 1: least the first that we know of, and that brings
Speaker 1: us to the person we mentioned at the top of
Speaker 1: the show, John Dalton. John Dalton was born in early
Speaker 1: September seventeen sixty six. His actual date of birth is
Speaker 1: either September five or September six. His parents, Joseph Dalton
Speaker 1: and Deborah green Up Dalton, were Quakers. His father made
Speaker 1: a living as a weaver. The Dalton's had three children
Speaker 1: who lived to adulthood, and John was the youngest of them.
Speaker 1: And as a child, John attended a Quaker school, and
Speaker 1: that school changed hands when John was twelve. John Fletcher,
Speaker 1: the man who had been running it, gave it to
Speaker 1: John Dalton's older brother, Jonathan Dalton, and then Jonathan enlisted
Speaker 1: John's assistance in this new role, and this set John
Speaker 1: on a path as an educator. Just kind of delights
Speaker 1: me that they had a John and a Jonathan. It
Speaker 1: makes me giggle as well. John and Jonathan expanded their
Speaker 1: new careers by taking over a school in Kendall, England,
Speaker 1: when John was just fourteen. This is a larger operation
Speaker 1: than the Quaker grammar school they had been running, and
Speaker 1: it included students who boarded as well as students. Has
Speaker 1: totaled about five dozen students in all, and John was
Speaker 1: sort of learning on a job. He was studying with
Speaker 1: scholars to learn math, Latin, Greek and science to stay
Speaker 1: ahead of his students and to be able to speak
Speaker 1: on the subjects of their curriculum. And keep in mind,
Speaker 1: again he's like fourteen fifteen at this fight, uh, so
Speaker 1: he is taking in a lot of information. And he
Speaker 1: stayed in that job for a dozen years and then
Speaker 1: at the age of twenty seven, John moved on to
Speaker 1: a new professional post as a mathematics teacher at New College,
Speaker 1: and this was in Manchester. And he found all this
Speaker 1: a little bit frustrating though, because his workload in that
Speaker 1: job prevented him from having time to pursue his own
Speaker 1: scientific study. So he switched gears and decided that he
Speaker 1: would become a private tutor so that he could manage
Speaker 1: his own time in a way that would enable him
Speaker 1: to carry on with his side work. At this point,
Speaker 1: his work outside of his daily teaching task was focused
Speaker 1: largely on meteorology. He had been publishing articles in the
Speaker 1: subject for several years, but he kept studying other sciences
Speaker 1: as well and all and it was through these studies
Speaker 1: that he wound up writing a paper that expounded on
Speaker 1: the idea that not everyone saw colors in the same way.
Speaker 1: So this was not the first time the mention of
Speaker 1: non standard color vision appeared in print. As we said earlier, surely,
Speaker 1: color vision divisiency has been in play almost as long
Speaker 1: as humans have existed, and even before Dalton there had
Speaker 1: been some mentions of it, including a write up of
Speaker 1: a man named Thomas Harris that was published in Philosophical
Speaker 1: Transactions and that described Harris's inability to distinguish colors, which
Speaker 1: was published in seventeen seventy seven. We're gonna come back
Speaker 1: to Harris, and we'll talk first more about John Dalton,
Speaker 1: but before we do all of that, we're going to
Speaker 1: pause for a brief sponsor break. John Dalton presented his paper,
Speaker 1: which was titled Extraordinary Facts relating to the s of
Speaker 1: Colors with Observations by Mr John Dalton, at Manchester's Literary
Speaker 1: and Philosophical Society on October. He had joined the society
Speaker 1: upon moving to Manchester. And as scientific papers go, this
Speaker 1: one is kind of unique in that Dalton himself is
Speaker 1: really the subject of the paper, or at least his
Speaker 1: vision was. That text opens with quote, it has been
Speaker 1: observed that our ideas of colors sounds, tastes, et cetera,
Speaker 1: excited by the same object, may be very different in
Speaker 1: themselves without our being aware of it. He goes on,
Speaker 1: quote I was always of the opinion, though I might
Speaker 1: not often mention it, that several colors were injudiciously named.
Speaker 1: The term pink, in reference to the flower of that name,
Speaker 1: seemed proper enough. But when the term red was substituted
Speaker 1: for pink, I thought it highly improper. It should have
Speaker 1: been blue in my apprehension, as pink and blue appear
Speaker 1: to me very nearly allied, whilst pink and red have
Speaker 1: scarcely any relation. He goes on in his introduction to
Speaker 1: mention how he had learned about light and optics in
Speaker 1: his scientific studies, but he hadn't really thought about applying
Speaker 1: any of that information to colors, because that entire area
Speaker 1: the idea of color seemed kind of confused, And on
Speaker 1: to them like he really was, like, why would people
Speaker 1: group these colors together? Doesn't make any sense, But I
Speaker 1: guess that's how we've always done it. Uh. It was
Speaker 1: not until he turned his scientific work to botany that
Speaker 1: he really started thinking about why some color groupings just
Speaker 1: made no sense. And this study prompted him to ask
Speaker 1: other people questions about colors. He actually uses the example
Speaker 1: in this paper of asking a person whether a flower
Speaker 1: was blue or pink. But they always just thought he
Speaker 1: must be joking because the queries came off as so
Speaker 1: completely absurd to them. So he just thought everybody had
Speaker 1: this weird relationship with color. Even though he thought colors
Speaker 1: made no sense, it didn't really occur to him to
Speaker 1: wonder if there was something unusual about the way he
Speaker 1: was perceiving colors. It was a moment in seventeen ninety two,
Speaker 1: two years before he presented his paper, that really gave
Speaker 1: him this moment of pause. That moment happened when he
Speaker 1: was looking at a geranium by candle light. So he
Speaker 1: had frequently seen these flowers, this particular variety he was
Speaker 1: looking at were in fact pink in daylight, and to him,
Speaker 1: in daylight he perceived them as sky blue, but by
Speaker 1: candle light, he saw this flower as a vibrant red,
Speaker 1: and this significant shift in their color due to lighting
Speaker 1: changes startled him and led him to make a quick
Speaker 1: study by asking a number of friends to look at
Speaker 1: these same flowers in both daylight and candle light. All
Speaker 1: the people he initially asked about it saw them as
Speaker 1: pink in both lighting conditions, except for his brother, who
Speaker 1: perceived that same shift of them being sky blue in
Speaker 1: the day and red in candle light. This experience caused
Speaker 1: him to start a more structured study of light and color,
Speaker 1: which he did with an assistant who had quote normal
Speaker 1: color vision. First, he used a prism to project sunlight
Speaker 1: into a dark room and then recorded the number of
Speaker 1: colors that various people saw in that band of light.
Speaker 1: Most of them saw six red, orange, yellow, green, blue,
Speaker 1: and purple. He does mention that purple is separated into
Speaker 1: indigo in violet and Newton's writings on color for the
Speaker 1: purposes of a person simply looking at a band of light,
Speaker 1: that distinction is really nominal. I think we talked about
Speaker 1: this in one of our episodes that touched on Newton. Previously.
Speaker 1: He put the indigo and violet in their separately because
Speaker 1: he wanted there to be seven. So that's why people
Speaker 1: typically don't actually see them. As to the state shades
Speaker 1: in light from a prism, yeah, or you'll see what
Speaker 1: you think is maybe a slight difference, but it's hard
Speaker 1: to be sure. So for for Dalton, he just called
Speaker 1: that one thing, it's purple. Uh. When Dalton looked at
Speaker 1: the prismatic light, though, he could only make out two
Speaker 1: or sometimes three colors, so generally he just saw yellow
Speaker 1: and blue, or sometimes he would see yellow, blue, and
Speaker 1: a little bit of purple. And through his work he
Speaker 1: identified that the band that he saw is yellow was
Speaker 1: where other people were seeing red, orange, yellow, and green,
Speaker 1: and he wrote quote that part of the image, which
Speaker 1: others call red, appears to me little more than a
Speaker 1: shade or a defective light. After that, the orange, yellow,
Speaker 1: and green seemed one color which descends pretty uniformly from
Speaker 1: an intense to a rare yellow, making what I should
Speaker 1: call different shades of yellow. Dalton's perception of blue and
Speaker 1: purple aligned with what other people were seeing, and the
Speaker 1: contrast between the end of his band of yellow and
Speaker 1: the adjacent blue was really sharp. So next he did
Speaker 1: the same collecting of perceptions from himself and others when
Speaker 1: looking at candle light projected through a prism, and these
Speaker 1: results were mostly the same. The only exception that Dalton
Speaker 1: calls out is that for him, the red edge of
Speaker 1: the image looks more vivid in candle light than it
Speaker 1: did looking at some light under the same conditions of
Speaker 1: being put through a prism. Dalton's paper next breaks out
Speaker 1: studies of specific colors as he had always perceived them.
Speaker 1: He starts out by describing colors grouped with red as
Speaker 1: they appear in the daylight versus candle light. His description
Speaker 1: of crimson is pretty charming quote Crimson has a grave appearance,
Speaker 1: being the reverse of every showy and splendid color. A
Speaker 1: similarly quaint description this is a description of pink. He
Speaker 1: breaks that down as nine parts light blue and one
Speaker 1: part red quote or some other color which has no
Speaker 1: other effect than to make the light blue appear dull
Speaker 1: and faded a little. He also lists out all the
Speaker 1: flowers that to him look blue to give the reader
Speaker 1: a sense of context. When he says he says pinks
Speaker 1: and reds as blue. Blood, he says appears to him
Speaker 1: as the color most people call bottle green, and he
Speaker 1: mentions that if he saw a light colored stocking that
Speaker 1: was spattered with either fresh blood or dirt, he would
Speaker 1: not be able to tell the difference visually. I love
Speaker 1: this entire paper so much. It's exactly like this. The
Speaker 1: way through his his turn of phrases, quite quite charming
Speaker 1: and endearing, He goes on to describe the significant change
Speaker 1: that red undergoes for him when viewed in candle light.
Speaker 1: He describes it as much more vivid, and the blue
Speaker 1: no longer being present and instead replaced by yellow tones.
Speaker 1: While he found most reds and pinks quite drabbed by daylight,
Speaker 1: in kindle light they became really vivid and even exciting.
Speaker 1: Orange and yellow, he says, are not too different for
Speaker 1: him than anyone else. When he moves on to discussing green,
Speaker 1: he writes, quote, I take my standard idea from grass.
Speaker 1: This appear is to me very little different from red.
Speaker 1: The face of a laurel leaf is a good match
Speaker 1: to a stick of ceiling wax, and so it will
Speaker 1: be immediately concluded that I see either red or green,
Speaker 1: or both different from other people. The fact is, I
Speaker 1: believe that they both appear different to me from what
Speaker 1: they do to others. He concludes that blues he generally
Speaker 1: sees the same as other people, and purple is just
Speaker 1: a little bit different from blue. He described brown in
Speaker 1: the same creative way that he does other colors, writing quote,
Speaker 1: my idea of brown I obtained from a piece of
Speaker 1: white paper heated almost to ignition. He also notes that
Speaker 1: seeing colors in moonlight presents the same or near same
Speaker 1: results for him as seeing them in candlelight. Lightning gives
Speaker 1: the same effect as daylight. It doesn't matter whether the
Speaker 1: sun is rising or setting when it comes to color,
Speaker 1: and any kind of combustible substance creates the same color
Speaker 1: perception as any other flame. He concludes the section of
Speaker 1: the paper with quote, my vision has always been as
Speaker 1: it is now. His next section breaks out the information
Speaker 1: that he's collected from other people and their perceptions of color,
Speaker 1: starting with people he has found who have vision that
Speaker 1: seems similar to his own, and Dalton mentions Mr Harris
Speaker 1: of Maryport and his alternate perceptions of color. Dalton thought that,
Speaker 1: based on the description, Harris's anomalous vision might have been
Speaker 1: different from his own. He discovered that one of Harris's
Speaker 1: brothers was still alive, so he made contact and went
Speaker 1: to visit. Upon questioning this brother and testing his vision,
Speaker 1: Dalton found that the Harris family seemed to have the
Speaker 1: same genetic variable that he and his brother had when
Speaker 1: it came to how they perceived the colors of the
Speaker 1: world around them. This led to a general line of
Speaker 1: questioning of the students and colleagues that Dalton regularly came
Speaker 1: in contact with, kind of as a subject group, and
Speaker 1: he found a small proportion of them share his specific
Speaker 1: experience regarding pink and light blue looking similar by daylight
Speaker 1: and different by candle light. Dalton also found just a
Speaker 1: couple of examples of people who quote differ from the
Speaker 1: generality and from us, also meaning that they seem to
Speaker 1: have a different type of color vision deficiency. He also
Speaker 1: mentioned a shared experience among all of these people that
Speaker 1: justice with him it had not occurred to them that
Speaker 1: they were seeing things differently from the majority of people,
Speaker 1: but that they too found the names and groupings of
Speaker 1: colors perplexing at times. Though his paper was really the
Speaker 1: beginning of sciences study of color vision deficiency, even in
Speaker 1: his really relatively small data set, Dalton was already capturing
Speaker 1: information that showed a difference in instances of color vision
Speaker 1: deficiency in regards to people's sex. He noted that in
Speaker 1: the Harris family, four of six sons in the family
Speaker 1: had what would come to be known as color vision deficiency,
Speaker 1: sometimes also called dalton is um for obvious reason, but
Speaker 1: their sister didn't. Similarly, Dalton and his brother Jonathan had
Speaker 1: the same color experience, but their sister did not. He wrote, quote,
Speaker 1: it is remarkable, but I have not heard of one
Speaker 1: female subject to this peculiarity. He also included the line
Speaker 1: quote I did not find that the parents or children
Speaker 1: in any of these instances have been so unless in
Speaker 1: one case. So, even though he didn't really realize it,
Speaker 1: he was gathering information on the recessive genetic nature of
Speaker 1: red green color vision deficiency. Next up, we'll talk about
Speaker 1: what Dalton thought was causing his anomalous vision, but first
Speaker 1: we will take a break for a word from our sponsors.
Speaker 1: The third section of Dalton's paper tries to unravel the
Speaker 1: cause of what he was referring to as quote our
Speaker 1: anomalous vision. One of the ways that he worked out
Speaker 1: his theory here was to work with transparent colored liquids,
Speaker 1: and then he would have various people look at objects
Speaker 1: through those transparent colored liquids to record their perception of color.
Speaker 1: So he would hold up a thing behind, like a
Speaker 1: tank of blue water, whatever um and ask them what
Speaker 1: they saw. And because people with you know, quote unquote
Speaker 1: normal vision described color similar to what he saw in
Speaker 1: his normal day to day life when they looked through
Speaker 1: a tank of blue water, he came to this incorrect
Speaker 1: conclusion that quote, one of the humors of my eye
Speaker 1: must be a transparent but colored medium, so constituted as
Speaker 1: to absorb red and green rays principally because I obtain
Speaker 1: no proper idea of these in the solar spectrum, and
Speaker 1: to transmit blue and other colors more perfectly. Honestly, this
Speaker 1: is a totally reasonable conclusion based on understanding. Right. He
Speaker 1: outlined how this would impact the perception of various colors,
Speaker 1: and then addressed why the colors changed so dressed for
Speaker 1: him and other others like him. In candlelight, writing quote,
Speaker 1: when any kind of light is less abundant in blue,
Speaker 1: as is the case with candle light compared to daylight,
Speaker 1: our eyes serve in some degree to temper that light
Speaker 1: so as to reduce it nearly to the common standard.
Speaker 1: The Earth's atmosphere, he believed was a blue fluid that
Speaker 1: quote modifies the Sun's light so as to occasion the
Speaker 1: commonly perceived difference. So this paper was met with some curiosity,
Speaker 1: and his very detailed comparisons of his vision to that
Speaker 1: of other people who saw color normally offered a lot
Speaker 1: of insights. But this idea of a blue humor in
Speaker 1: his eye that was causing his anomalous color vision was
Speaker 1: kind of dismissed by the scientific community, and in response, Dalton,
Speaker 1: who really thought he was onto something with it, donated
Speaker 1: his eyes to science. He wrote up a document that
Speaker 1: requested that his eyes be dissected upon his death to
Speaker 1: see if he had been correct and whether there was
Speaker 1: any other physical evidence to explain the way he perceived color.
Speaker 1: A little less than a decade after Dalton's writing on
Speaker 1: his anomalous vision, scientist Thomas Young published on the theory
Speaker 1: of light and colors, and this put forth the idea
Speaker 1: that there were receptors in the eye for each of
Speaker 1: the colors red, green, and blue. So he was totally
Speaker 1: onto it, and Young addressed Dalton's work and his anomalous
Speaker 1: color vision with a different theory that there was a
Speaker 1: quote absence or paralysis of those fibers of the retina
Speaker 1: which are calculated to perceive red. He was so completely
Speaker 1: on the right track that you would think that this
Speaker 1: would have just broken eye science wide open. But no, no,
Speaker 1: it advancement slowed down after this and studying the eye
Speaker 1: and that went on for decades. Yeah, it was like
Speaker 1: people are like neat idea and they moved on to
Speaker 1: other stuff. Um Beyond the study of color vision deficiency.
Speaker 1: John Dalton of course continued to make important contributions to
Speaker 1: the scientific world. Concurrently, while working on figuring out why
Speaker 1: he couldn't see flowers the same way as other people,
Speaker 1: he also published a work titled Meteorological Observation and Essays.
Speaker 1: He published additional work in meteorology as well, and his
Speaker 1: work in this field led to some fellow scientists considering
Speaker 1: him the father of meteorology, although his work. Anytime somebody
Speaker 1: gets called the father of something, I always have to
Speaker 1: go because his work was of course building on that
Speaker 1: of his mentors on this subject. He had particularly had
Speaker 1: a really good mentor in meteorology when he was studying
Speaker 1: as a teacher. Dalton also did a lot of work
Speaker 1: in chemistry, specifically atomic theory. His work in this area
Speaker 1: came to some incorrect conclusions, but it was also instrumental
Speaker 1: in moving the scientific community away from the long held
Speaker 1: idea that matter was at the basic level all the
Speaker 1: same and just configured differently to form different things. Dalton
Speaker 1: championed the idea that there were all kinds of different
Speaker 1: atoms with different sizes and weights, and that they behaved differently.
Speaker 1: He started a project to measure the masses of different
Speaker 1: atomic particles to begin cataloging all of the different atoms
Speaker 1: that could be found. He presented the first table of
Speaker 1: atomic weights in eighteen o three, and his work in
Speaker 1: this area propelled organic chemistry forward. He is also sometimes
Speaker 1: called the Father of chemistry. Dalton had joined the Manchester
Speaker 1: Literary and Philosophical Society in seventee when he was still
Speaker 1: in his twenties. In eighteen seventeen, as a man in
Speaker 1: his early fifties, he became its president. He held this
Speaker 1: position for the rest of his life. His scientific career
Speaker 1: slowed down quite a bit. Yeah, there were some other
Speaker 1: issues where his He had some papers that were denied
Speaker 1: for publication, and it just wasn't like the heyday he
Speaker 1: had had when he was a little younger. He had
Speaker 1: a unique distinction though, of seeing for example, his own
Speaker 1: statue erected in Manchester during his lifetime for his accomplishments,
Speaker 1: and while he had been barred from an education at
Speaker 1: Oxford or Cambridge as a young man because he was
Speaker 1: a Quaker not an Anglican, he received honorary degrees from
Speaker 1: both later in life. He also served as a foreign
Speaker 1: Associate of the French Academy of Sciences. On April eighteenth,
Speaker 1: eighteen thirty seven, Dalton, who was seventy at the time,
Speaker 1: had a stroke that resulted in a partial paralysis, and
Speaker 1: then he had another small stroke or possibly a seizure
Speaker 1: several days later. Being pretty pragmatic, he set his affairs
Speaker 1: in order as soon as he was recovered enough to
Speaker 1: do so. But then he lived another seven years. He
Speaker 1: continued as president of the Literary and Philosophical Society. He
Speaker 1: made visits to Lake Country. That's something that he had
Speaker 1: been doing throughout his life. Yeah, it was a very
Speaker 1: close call, and then he kind of was like, well,
Speaker 1: I'm still alive. I'm gonna keep doing my living stuff. Uh.
Speaker 1: John Dalton died finally on July forty four. He was
Speaker 1: really really beloved in Manchester by this point, and he
Speaker 1: was given a public funeral all by the city on
Speaker 1: August twelfth, eighteen forty four, and estimated forty people paid
Speaker 1: their respects before Dalton was interred. The day after Dalton's death,
Speaker 1: on July eighteen forty four, his wishes were carried out
Speaker 1: his eyes were dissected. This was done by Dr Joseph
Speaker 1: Bransom to determine whether this idea about having a blue
Speaker 1: humor in his eye was correct. Of course it was not.
Speaker 1: Ransom described what he found in Dalton's eye as quote
Speaker 1: perfectly pellucid and some also sliced off a section of
Speaker 1: the posterior pole of the eye and used it as
Speaker 1: a lens to see if colors that were viewed through it,
Speaker 1: especially red and green, took on a different hue, which
Speaker 1: they did not. But Dalton's eyes were not discarded after that,
Speaker 1: so for clarity he did the full dissection on one eye.
Speaker 1: That little part he sliced off was from the second eye,
Speaker 1: um so he had only taken the primary samples from one.
Speaker 1: The other was mostly intact, and the remains of Dalton's
Speaker 1: eyes were preserved and were even actually given to the
Speaker 1: Manchester Literary and Philosophical Society. That was not the end
Speaker 1: of their story. A hundred years after Dalton died in
Speaker 1: a DNA analysis was conducted on his preserved eyes, and
Speaker 1: this examination determined that he had due to anopia, conclusively
Speaker 1: proving that he had red green color vision deficiency. Two
Speaker 1: years after those findings were published in seven the eyes
Speaker 1: were donated to the Science and Industry Museum in Manchester
Speaker 1: and they remain in the collection there to this day. Yeah,
Speaker 1: you can find pictures of him online. Uh. In the
Speaker 1: eighteen seventies, German anatomis Max Schultz identified the rods and
Speaker 1: cones of the retina and deduced that rods were dedicated
Speaker 1: to night vision and cones to daylight vision. Then later
Speaker 1: in the eighteen seventies, Wilhelm kun laid the groundwork for
Speaker 1: a concept of photochemical basis for vision. In the nineties,
Speaker 1: Spanish neuroscientists Santiago Ramonica how studied the retina and drew
Speaker 1: detailed diagrams of the cells within it. How scientific drawings
Speaker 1: are incredibly intricate and very beautiful, and they were part
Speaker 1: of an art exhibit at n y U. Yeah. So
Speaker 1: you know, all of the things that would have explained
Speaker 1: to Dalton what was going on came a little too late.
Speaker 1: There was also a cool discovery so fairly recently, a
Speaker 1: new kind of photo receptor was discovered, the ganglion cell,
Speaker 1: and that once again refined our knowledge of how the
Speaker 1: human eye takes in and processes visual information. Always learning. UM,
Speaker 1: I really really really love John dalton story, and I
Speaker 1: love this part of it. Um. I knew a little
Speaker 1: bit more about you know, his work in in establishing
Speaker 1: the basis of a lot of the chemistry we use,
Speaker 1: but I didn't. I had never read this paper before,
Speaker 1: and I honestly it's the most fun reading. It's very sweet.
Speaker 1: I will switch gears completely form our listener mail though
Speaker 1: okay one I won't read his mail because it's pretty short,
Speaker 1: but I'll sum it up. I wanted to say hi
Speaker 1: to Todd who wrote us he was listening to our
Speaker 1: transfusion episodes while he donated platelets. So thank you Todd
Speaker 1: for donating platelets. We have had several people right in
Speaker 1: to make sure that we uh let people know that
Speaker 1: donating blood is very important and it is. So this
Speaker 1: is your p s A again and again, thank you Todd.
Speaker 1: But my actual email that I'm gonna read is from
Speaker 1: our listener, Larissa. I think that's probably how she pronounces it.
Speaker 1: Who writes Hi, Holley and Tracy. I've been a fan
Speaker 1: since sixteen and I always look forward to new episodes
Speaker 1: each week. It helps keep my brain limber while at
Speaker 1: home with the kids during lockdown, which we are currently
Speaker 1: experiencing here in Ontario. Recently, I have been thrilled to
Speaker 1: make connections between your podcast in my library. I just
Speaker 1: finished reading Scherie Demelin's Empire of Wild, which is a
Speaker 1: novel set within the Matti community of Georgian Bay, Canada,
Speaker 1: in which a rugarou plays a major part. The moment
Speaker 1: of the novel that answered the niggling part of my
Speaker 1: brain that said, Ruguru, Where have I heard that before?
Speaker 1: Was when one of the characters leaves thirteen objects on
Speaker 1: her porch to protect herself because the rugarou can only
Speaker 1: count to twelve. I'm so curious about how the creature
Speaker 1: became part of both culture. Surely the link must be
Speaker 1: the French. This may have set off the great rugaru
Speaker 1: investigation of one on my part, invest which is yes,
Speaker 1: we mentioned in that episode, although we didn't go super
Speaker 1: deep because there's not really documentation of it that Since
Speaker 1: Ruguru is kind of a shift from Lugaru, which is
Speaker 1: French for werewolf, it seems to have traveled over with
Speaker 1: French colonists, uh, and French fur trappers kind of became
Speaker 1: pretty standard in in that area in the north and
Speaker 1: then migrated south into Louisiana. That is the best guess
Speaker 1: how it traveled since we don't have, like I said,
Speaker 1: hard documentation him. But I love that the Rugaru and
Speaker 1: his inability to count beyond a dozen is still delighting
Speaker 1: people and making us all laugh because we need it
Speaker 1: right now. Uh. If you would like to write to us,
Speaker 1: you can do so at History podcast at iHeart radio
Speaker 1: dot com. You can also find us as Missed in
Speaker 1: History everywhere on social media. If you have not subscribed
Speaker 1: to the show, why not, You can do it right now.
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