Resources For Educators: The Nature of Color

Hello, and welcome to all the educators and to all of my colleagues. It's so great to have you here with us on our first virtual Educators Evening. I'm Dr. Linda Curtis-Bey. As Alonso said, I'm Director of the Gottesman Center for Teaching and Learning, which focuses on you, our educators, at the American Museum of Natural History.

It is my pleasure to welcome you all to this evening and to introduce the exhibition's curator, Dr. Rob DeSalle. Dr. DeSalle is a Curator of Molecular Systematics at the American Museum of Natural History. He is affiliated with the museum's division of invertebrate zoology and is a principal investigator at the Institute for Comparative Genomics where he leads a group of researchers working on molecular systematics and microbial evolution and genomics.

His current research concerns the development of bioinformatic tools to handle large-scale genomics problems using [? phylogenetic ?] system-- [LAUGHS] systematic approaches. Welcome, Dr. Rob DeSalle. He has curated several of the museum's landmark exhibits, including "Brain: The Inside Story," "Our Senses: An Immersive Experience," and most recently, "The Nature of Color." Welcome.

Hey. Thank you, Linda. And you nailed systematics.

Yay!

I know you were a little worried about that. That's a tough word. Welcome, everybody. It's a real pleasure for me to be here this evening, I should say, because this is an Educators Evening. I'm very sad, though, that I'm not in the Hall of Ocean Life speaking to you all beneath the blue whale. This should be pretty good, though. This should be a lot of fun. The folks in the education department have worked really hard to put this together, and I hope you have a good time this afternoon.

The other sad thing about color and about this talk is that the exhibition itself, "The Nature of Color," opened at the museum two days before [LAUGHS] the pandemic sanctions started. And so the show itself has sat for almost a year with very limited visitorship. So I hope in the next few months, we can fix that and pour people through it. It's a wonderful show and it's one that I hope you all enjoy, and I hope you take advantage of for your students and for your courses.

It's one of these rare shows where almost every part of the museum has something relevant to say. Color is a story about physics, astrophysics. Color's a story about anthropology. Color can be told from the context of vertebrates. Color can be told from the context of invertebrates. It can be told from the context of fossils, even. So it's one of these great, great subjects that I think is a really wonderful one, and one that I'm sure your students are going to enjoy.

I'm going to start my slides right now. Just sorry for the delay here. OK. So can everyone see the slide on your screen? I hope so. OK, great.

Color is a physical thing. And as Alonso's question alluded to, even though this prism is showing color coming from the white light, the wavelengths themselves are not colorful, nor are they visible. They're detected by your eyes, as we'll see here in a second.

And color as I said is a story about physics. And here we see Sir Isaac Newton doing his famous prism experiment where he fragmented white light into all of the lights of the color spectrum. And in the show, we have a small kind of mock-up of what Sir Isaac Newton did with his prism study.

So again, color comes to us via light waves. And one of the entrance parts to the show is a two-scale depiction of the range of visible light and what colors the wavelengths of visible light make.

And by two-scale, I mean it's one to one millionth. So wavelengths of light that we visualize are usually measured on the scale of nanometers, from 380 or so to 750 nanometers. And every nanometer that we see in the spectrum is represented by one millionth larger scale up on this part of the show.

And it gives you a sense of the range of visible colored light, visible light that we use and that we interpret as colors. And in the lower left-hand corner here, you can see that electromagnetic radiation, which is what we detect when we detect light and we detect colors, ranges over a wide, wide range of wavelengths from kilometers' long wavelengths to thousandths of a nanometer.

And it's spectacular that our eyes and the eyes of other organisms on this planet detect light through a very, very-- a short range of light, and that is from about 350 to 380 in the violet end of the spectrum to 750 or so in the red end of the spectrum. And beyond the violet end of the spectrum is the ultraviolet, and beyond the red end of the spectrum is the infrared part of the spectrum, parts of the spectrum that we don't see or visualize or interpret.

Now, let's just step back and ask, what are we seeing when we see colors? This beach ball is a really interesting object, and it's a subject of one of the videos in the show. And what we have here is essentially a piece of plastic, several pieces of plastic with some air inside of it. And each of the pieces of plastic is made of polymers, but infused with the polymers are dyes or colorants. And these colorants are made up of molecules.

And so the yellow dye or colorant that makes the yellow part of the beach ball might look like this molecule here, which is a yellow colorant molecule. The red would have a little bit larger molecule, and the blue would have an even larger molecule.

And so if you can imagine these three molecules being distributed across these different regions of the beach ball, then that's what we actually are dealing with when we attempt to use our visual system to visualize color. It's just molecules. And these molecules have really interesting properties. This is what the beach ball would look like if you stripped the colors away.

And the molecules have a very interesting property, and that is that white light, which is a mixture of-- as Sir Isaac Newton showed-- is a mixture of all of the colors of the spectrum. When white light hits the ball, it hits the plastic, it hits the polymers, light will go through the polymers. It will partially reflect from the polymers. But when light hits these colorant molecules, some of the light waves will be absorbed by the molecule and some of the light waves will be reflected by the molecule.

And what we'll see is that white light hitting the yellow colorant will absorb all of the wavelengths except for the yellow wavelength. And the yellow wavelength will be reflected, and these are the wavelengths that reach our eye. And these are wavelengths between 580 nanometers and 610 nanometers. Everything below 580 gets absorbed by the molecule. Pretty much everything. And everything above 610 are absorbed by the molecule. And it's only those wavelengths of light that are in between that are reflected. And these are the wavelengths that hit your eye.

Now, what happens, though, if we bounce different kinds of white-- of light off of these colors? So here is part of an exhibit in the show where there's a room with a really interesting painting on the wall. And the room is bathed in white light. And as you stand there, the room then gets bathed with pure yellow light.

And so what happens is that all of the blue, green, and red light that was reflecting in the right-hand side gets eliminated because it's not in the source of the light. And so all you see is yellow light reflecting off of the surfaces. And when that happens, the shades of yellow light that make it to your eye are all that you see, and it makes a rather dull color impression.

The actual biological basis for color vision resides in our eyes, of course, and light comes in through the lens. It's focused on the back of your eye where your retina lies. And your retina is made up of a bunch of cells, kind of a field of cells called rods and cones. And there are three kinds of cone cells. Red, green, and blue. There's actually two kinds of red ones, but they're grouped together.

These rods and cone cells are the cells that collect the light, that interact with the light, and then send a message to the brain via the optic nerve. And so what happens is the light that's reflecting off of the objects that you're viewing come into these cone cells.

And if, say, this is a red cone cell, a cone cell that's constructed by your genome to detect red light, if it's red light, then it will interact with the protein in the cell membrane of the cone cell called an opsin. And this opsin will change shape and cause a transition in the cell that creates an action potential that then goes to your brain.

And then the information gets to your brain and is processed in the back part of your brain, in your optic lobe of your brain, in two directions, one upper direction and one lower direction. These two ways of processing the object and the color are what eventually give you your image of color.

The biology of this is really amazing. Humans have three kinds of opsin genes that work in cone cells. Blue, green, and red. And the reason that the mantis shrimp that Alonso mentioned has such great color acuity is that instead of only three opsins, it has between 12 and 16 opsins, different opsins that detect light at different wavelengths. And it's this detection of light at different wavelengths that really makes color come to life in our brains and the brains of other organisms.

The show itself is really, I think, cleverly laid out. And I wish I could claim some of that cleverness, but it's actually due to Lauri Halderman and her crew in the Exhibitions department.

And one of the things that we tried to get the visitor to realize about color is that color is really connected to us, and it's really connected to our emotions and to our way of dealing with the world. And in this really great interactive, you're asked a series of seven or eight questions, and you answer them.

And you might be saying, well, what about COVID? Why should we be touching screens? Well, you can actually play this in the hall on your phone by scanning a digital code and going right on to the museum's computers and playing this game.

And we ask questions here like this one. Which of these-- which of these does your mood relate to? Which of these colors? And it's sort of a survey that gives the visitor a sense of how color affects their emotions and how color affects the way that they're feeling.

And it's really interesting. And it's interesting because colors do have a huge impact on how we deal with the world. This is a figure from a study that showed that children prefer plates of food with more color on them. And the experiments were done such that children were offered choices between, say, 1 and 5. And children would almost always choose 5. And so the more colorful the plate, the makeup of the food on the plate, the more likely a child is to choose that food to eat.

There are all kinds of experiments done like this with color and with other senses in the context of commercial preference. And this is in the field of neuroeconomics. Color is a very important aspect of neuroeconomics and how people, including children, make decisions about things like what they want to eat, what they want to buy, things like that.

Another section of the show-- and the show is separated into five major galleries-- yellow, which we just saw, green here, red, and blue that we're going to see in a second, and a major white hall. The green hall is about biology. And the biology of color is spectacular, and this is because organisms evolve, and color is one of the major things that researchers have looked at in the context of evolution.

Darwin and Wallace both used color in their studies to establish the existence of evolution, to give all of their examples of the existence of evolution, and indeed, to come up with their ideas about natural selection. And in this room, there are several stories about color in nature.

But I wanted to turn to one of my favorite biologists, this guy. [LAUGHS] And color is involved in all of these adaptive ways that organisms deal with the world.

So the first one is "ay-posematism" or aposematism, And aposematism is simply warning, warning coloration. And in this cartoon, we see three ways that animals warn other animals that they're dangerous. And a fourth down there in the corner, how nature says, do not touch.

Nature also says do not touch with color. And so bright red colors are usually-- have usually evolved in organisms that are poisonous to warn off other organisms that they are poisonous. Bright yellows and bright blues and bright color is a warning coloration.

Another is through mimicry. And mimicry systems involve a lot of color. And here is a cartoon showing when animal mimicry breaks down. And when animal mimicry breaks down, it means that the predator has decided that it won't be tricked by the mimic. And again, color is used in a lot of these mimicry systems.

Here, we have camouflage. And when the monster came, Lola, like the peppered moth and the Arctic hare, remained motionless and undetected. Harold, of course, was immediately devoured. It's essentially wonderful natural systems that we observe where camouflage exists. And again, camouflage is one of these things that Darwin and Wallace examined in great detail. And while the cartoons I'm showing you here are all in black and white, you can imagine them in color too.

And finally, biological color. This cartoon says, Nick, the fireflies across the street, I think they're mooning us. And Gary Larson, who drew all of these cartoons and came up with them, is perhaps one of the best biologists I've ever encountered. And in this particular case of color, the neighbors are fluorescing or bioluminescing as a result of the production of chemicals in their bodies that make light that are detected by the eyes of other organisms.

We go on to the red room. And the red room is all about human society and human cultures. And as you learned from the quiz at the beginning of the evening, cochineal, which is a red dye, was obtained through the use of cochineal beetles. And these beetles exist in South and Central America and were used by the South and Central American cultures to color garments and to color other kinds of objects.

Red can mean a lot of things. And red indeed has meant a lot of things to a lot of the different cultures. And red is very-- color is very important in understanding preferences. And here, we see Gainsborough's "Blue Boy" on the left and "Pink Boy," his "Pink Boy" on the right, and a second artist's rendering of a girl in pink.

These colors have a lot to do with the way that the person who views the painting interprets the meaning of the painting. And indeed, through cultural context and through cultural movements, blue began to be associated with maleness. Pink began to be associated with femaleness. And we address this concept in the show and attempt to understand-- attempt to give explanations for how these different color schemes and different color preferences came about in human populations.

And you have to realize that color in natural organisms, in populations of organisms arise and fall through natural selection. But color in human cultures rises and falls as a result of cultural norms and cultural preferences. So we oftentimes see really rapid changes in preferences for colors in human populations and in human cultures, whereas these rapid changes simply don't happen in populations of organisms where natural selection is the moving factor.

The blue room is also a room about functional coloring through dyes and through colorants. And the major interactive in this room is one where you isolate indigo from indigo leaves via an interactive. And the blue room tells the story of how humans adopted colors and how humans used colors in their cultural context.

The show also talks about skin color. And this is an exhibit from an artist who photos individuals and matches their skin color with a Pantone background. So this is a lot like trying to match a wall color with a paint color.

And this artist points out that of the 1,500 or so photos she's taken, she's only had a couple of individuals who have had-- who have been matched to the same Pantone background. So imagine this. Alonso pointed out that we can see 10 million colors. We have the capacity to see 10 million colors. But even for skin color, we see at least 1,500 as documented by this artist. And it's a really stunning exhibit showing the breadth of human skin color and how human skin color comes about biologically, and how human skin color is viewed by humans.

Then we try to end the show with some fun, and this is an area where the visitor can play with color. Color is a really important aspect of our lives. And if we didn't have color, we would lose a lot of meaning in our lives.

And this does not, however, mean that people who are colorblind have color-- have a color deficiency or cannot enjoy life as much as people with color, but it certainly means that we have a lot of things that we can do with color and a lot of things that help us think about the world through color.

This part of the show is one that I like to just sit and watch, and to think about color and what color means to me and what color means in a more or less philosophical context. And color itself, as was pointed out in one of the questions at the beginning of this evening's presentation, is really not that colorful. It's our brains that make our perception of color colorful, and it's our brains that interpret the colors and the things that we see in nature.