This helps confirm my theory that all reindeer have some type of light emission from their nose and Rudolph was the result of a mutation that moved the light emission to visible spectrum.
This would suggest all reindeeer emit UV light form their nose which they use to communicate with one another.
Nonamerican here. Is the joke that the nose is typically/always lit up in decorations? (Sorry if I'm ruining it by asking to confirm an explanation of the joke; I could rot13 it if that makes the situation any better ^^')
The joke is simply referring to "Rudolph the Red Nose Reindeer," one of Santa's reindeer that has a bright red nose to help light the way. Those decorations would also be referring to Rudolph.
Well, all the childhood cartoons show Rudolph’s nose glowing red.
Of course, with a bright glowing red omnidirectional light source directly in front of the eyes, it’s a bit strange he or anyone else in the sled could see where they were going!!! (Nobody talks about that)
> The reindeer is the only mammal with a color-shifting retroreflector behind the retina and the only ruminant with a lichen-dominated diet. These puzzling traits coexist with eye fluid that transmit up to 60% of ultraviolet (UV) light, enough to excite the cones responsible for color vision. It is unclear why any day-active circum-Arctic mammal would benefit from UV visual sensitivity, but it could improve detection of UV-absorbing lichens against a background of UV-reflecting snows, especially during the extended twilight hours of winter. To explore this idea and advance our understanding of reindeer visual ecology, we recorded the reflectance spectra of several ground-growing, shrubby lichens in the diets of reindeer living in Cairngorms National Park, Scotland.
Ruminant (i.e.: animals that ruminate) is one word I didn't know in English yet but has no simpler synonym: the thing that cows do where they eat their food multiple times. Apparently reindeer are ruminants.
Lichen is another word that I didn't know other than from Minecraft. The actual definition is this (Merriam Webster): "any of numerous complex plantlike organisms made up of an alga or a cyanobacterium and a fungus growing in symbiotic association on a solid surface (such as on a rock or the bark of trees)".
Now, if someone could shed (UV?) light on why the paper's title is chosen the way it is (how is this useful to anyone? When you get this as search result, how're you gonna tell whether this is relevant to what you're looking for? Why not use the title that the HN submission¹ used?), I'd be rather interested
¹ "Reindeer can see UV light" at the time of writing
Thank you, very helpful! As to why they didn't use something like a "Reindeer can see UV light" title, my understanding is that was already known, and this study provided evidence that the selective advantage of this trait is that it allows them to see their food source (lichens) better.
That sounds like there is still a better title possible a la "Reindeer's UV sensitivity allows them to see lichens better", rather than just making some pun that reduces the information to "something about reindeer in Scotland"
Ruminant: an herbivorous, even-toed, hoofed mammal (suborder Ruminantia and Tylopoda) that has a complex 3- or 4-chambered stomach. The word "ruminant" comes from the Latin ruminare, which means "to chew over again". Related to the English word ruminate, "think deeply about something"
I seem to be unfamiliar with all of your acronyms. Dictionary service for anyone else:
FWIU=From What I Understand; KNF=Korean Natural Farming; JADAM seems to be an uppercase-stylized brand name from what I can tell after some searching (https://en.jadam.kr about page: `He established JADAM (meaning "People that resemble nature") in 1991, and opened website www.JADAM.kr`)
Fun fact - Some humans can see UV light. People that have had their lenses removed, normally due to having cateracts surgically removed. I know this because i had my lenses removed at 3 months old and have worn contact lenses my enitre life. The first time i became aware i could see UV light was in a bowling alley with black lights, where one of my contact lenses had uv filtering and the other did not. A very disorienting experience. This is my very low-key superpower.
Stupid question probably: does sunlight on days where there are high UV radiation warnings (announced so people know to not stay in the sun too long and avoid sunburns) look any different to you?
Do you know what part of the UV spectrum you can see?
Edit: hmm, and the article's abstract says that reindeer' eye fluid is 60% transparent to UV (I assume that means "60% at the average thickness/depth of a reindeer eye from lens to retina"). That sounds like other animals' generally does not. Does humans'? I guess it must if you're seeing it, or you have special eye fluid!
No stupid questions.
This is not something i have noticed before. I don't think I am able to discern the difference to be honest. The sun during the day just looks like white, yellowish light to me.
Is there a way to compare what you see with what the average person sees? Would a “calibrated” photograph of a sunny day let you “see” what people see when they have “normal” vision?
Fellow aphakic here, can confirm. I never knew what people were talking about when they said blacklights, they just look like a real bright intense pinkish/purple light.
I only realised one day when I noticed that some kinds of lights looked really dark through my glasses but really bright when I took them off.
Ok, but for people with normal vision: when you look directly at a UV bulb, are you “supposed” to see an intense (brighter than any object fluorescing under the bulb) purply color that is hard to bring into sharp focus, or does it just look like a bulb that is switched off / totally dark?
It depends on the bulb. “Black light” used to mean a very specific fluorescent tube tech with a specific wavelength output, but now there are all sorts of different methods and wavelengths out there and each of them looks different to the eye (average vision and I’m assuming those with UV vision also).
UV LEDs are the worst offenders for this as their spectrum can be all over the place even due to QC-passing manufacturing defects.
I have been curious in the past about how much of it is that effect (ie- how much further away from the ‘visible’ UV spectrum I can actually see). It’d be interesting to know.
It looks like it's basically the entire ~315-420nm range. And, we normal/phakic people are technically sensitive to all of those wavelengths too—they're just very heavily, not completely, attenuated by lens absorption. Your relative sensitivity is greater by a factor of maybe 10,000, at 350 nm.
I can also see black light as deep purple, but I never had eye surgery. I think this due to the fact that spectra of UV lights spread into the visible range as well, but the peak emission is at UV-A.
For me they’re like a whitish-purple (intensely purple) but bright like any other regular light. About as bright or only slightly dimmer than the objects that glow from them.
I thought most humans could? I can definitely discern UV light from other sources. What does it look like to you? Very curious. A white shirt, white teeth etc dawn a very bizarre bright appearance under UV light. Tennis balls too.
If you have a UV light and look at the bulb or LED, you don't see any light coming from it at all? The bulb just looks to you like it isn't on?
UV bulbs look bright purple to me. They are so intense, I can barely even look at them directly. I always thought they were called black lights because they do not appear to light up a room (excepting materials that fluoresce under UV light); the UV light itself is very bright, but everything else stays almost as black as if there were no light at all.
I don't think I can see UV light, though. I don't see UV patterns on flowers that have them, for example. I think I am just seeing some violet light that UV bulbs also release, and maybe it feels so bright because the invisible UV stings my eyes.
Everyone can see that. Those old “black light” fluorescent tubes had filters that eliminated most of the visible light and appeared a dim purple when on… but modern UV LEDs and such emit plenty of visible light.
Fluorescent things shift frequencies, normal light reflection does not. You wouldn’t see any UV light in a dark room unless it struck something fluorescent. Plenty of things are not at all fluorescent.
I figured that there is something below the rank of species that differentiates them then, but checking what the word for that would be, there is none! Species is the most specific classification of life forms (https://en.wikipedia.org/wiki/Taxonomic_rank), so then they should be literally the same animal (every caribou is a reindeer and vice versa). Checking Wikipedia:
> "Reindeer is the European name for the species of Rangifer, while in North America, Rangifer species are known as Caribou." The word reindeer is an anglicized version of the Old Norse words hreinn (“reindeer”) and dýr (“animal”) and has nothing to do with reins. The word caribou comes through French, from the Mi'kmaq qalipu, meaning "snow shoveler", and refers to its habit of pawing through the snow for food.
> I figured that there is something below the rank of species that differentiates them then, but checking what the word for that would be, there is none! Species is the most specific classification of life forms (https://en.wikipedia.org/wiki/Taxonomic_rank), so then they should be literally the same animal (every caribou is a reindeer and vice versa).
What? That's like saying that cauliflower and cabbage must be literally the same plant.
Reindeer and caribou are differentiated by which continent you find them on. To the extent that it's difficult to walk from Canada to Norway or Siberia, they will have associated genetic differences.
> Cauliflower is one of several vegetables in the species Brassica oleracea
clicks on the latter
> Brassica oleracea is a plant species from family Brassicaceae that includes many common cultivars used as vegetables, such as cabbage, broccoli, cauliflower, kale, Brussels sprouts, collard greens, Savoy cabbage, kohlrabi, and gai lan.
I'm sorry, what?! All the same species? What's the point of calling something a species if it's a different plant or animal! That's like grouping cats and dogs as the same species called Quadlegs Adorables
More seriously, goes to show how little I know about this. Thanks for pointing out how silly a thing it was for me to be surprised that there are different words for the same animal .. when it's not actually the same animal/plant necessarily! I did not know this was a thing. I did hear about definition problems and proposals of "when it can produce viable offspring" or something, but they didn't say that cabbage and cauliflower produces viable offspring which would 180° change my idea on whether that's a useful lowest taxonomy class.
> it's difficult to walk from Canada to Norway or Siberia, they will have associated genetic differences.
I was surprised about that indeed, but less so now that I know that "one species" != "scientific way of saying 'one animal/plant/thingy'"
> What's the point of calling something a species if it's a different plant or animal! That's like grouping cats and dogs as the same species called Quadlegs Adorables
There is a lot of essentialism that went into initial efforts at taxonomy and a lot that people believe instinctively that they bring to their own modern understanding of it.
By now it is agreed that the correct use of taxonomy is to classify organisms in groups according to common descent from earlier organisms. This was not true as recently as the 1980s, when my mother's college biology textbook included a "teach the controversy" section explaining that that was one approach to taxonomy, but there were other approaches that also made very good points. [Editorial note: there were other approaches, but of course it isn't true that they made good points. They made points like "it's important for each taxon at a given level to contain the same number of species as the other taxa at that level".]
Anyway, once you lose the essentialism, you discover that there is no way to determine what label ["kingdom" / "class" / "genus"...] should be given to a taxon. [= a group of organisms sharing common descent from an ancestral organism.] So you see that divisions between taxa that are important, but that don't match up to traditional boundaries, are given names like subspecies, subfamily, and infraorder.
You might consider why you think it's absurd to unite the categories of "cats" and "dogs", but you see no problem uniting "dachshunds" [tiny and oblong, aggressive, like entering burrows to hunt] with "newfoundlands" [huge, affectionate, like rescuing humans from water]. Just the size differences are such that a female dachshund is unlikely to be able to breed with a male newfoundland. But also consider that rescuing drowning humans is such an important part of the newfoundland lifestyle that they have webbed feet.
Right, but GP's point, the jokey title doesn't actually convey much about the study.
I know many articles like to have funny titles. I wonder if this might start to change as people start to use AI more to go through 100,000 journal article titles to quickly see which ones may be useful to their research.
Wouldn't that allow titles to now contain exclusively humoristic content, because the AI already read the whole paper for you and matched that against your search request rather than merely the title and/or abstract?
I was already wondering if the ability to search abstracts (and modern engines are pretty good at matching synonyms as well unless you "quote" the keyword), and the displaying of excerpts below each title (like any web search engine does), is what makes the current situation workable.
I read in Arctic Dreams (Barry Lopez) that polar bears are hard to detect in the visual (white on white) and infrared (very good thermal insulation) spectrums, but that they are easily detectible in the ultraviolet spectrum due to the particular qualities of their fur. I'd suggest this is a reason that UV vision has developed in reindeers. Polar bears are the largest land predator in that region, and being able to see it in the only spectrum it's really detectable in would be a major benefit for reindeer.
The abstract mentions a similar hypothesis in regard to wolves and their prey:
> White wolves are well camouflaged on white landscapes; unless the prey are sensitive to UV light. It is an appealing hypothesis, but wolves in circum-Arctic habitats subsist on a variety of ungulate species––moose (Alces alces), muskoxen (Ovibos moschatus), roe deer (Capreolus capreolus)––which predicts similar selective pressures on their visual systems (Dominy & Harris, 2022). Studying the eyes of these animals may prove rewarding but, to date, there is little indication they share reindeers’ distinctive visual abilities.
This hypothesis depends on the predator-prey system not yet having reached equilibrium. Animals are white in the snow because that makes them hard to see, not by coincidence. (Where snow isn't present year-round, the same animal will usually be white in the snow and brown in the summer!) If wolves benefit from being white in the visible spectrum, and their prey starts detecting them by ultraviolet light they reflect, they should respond by turning whatever the analogue of white is in the UV spectrum.
To explain the UV vision of some prey animals as an adaptation to the fact that their predators are otherwise difficult to see, you'd need an additional assumption along these lines:
1. UV vision is a recent development in the prey animal. Eventually the predator will develop UV camouflage, but this just hasn't happened yet.
2. UV camouflage is inherently difficult. (Might be true! This is the generally accepted theory for why insects, reptiles, and birds can be blue, but mammals can't -- mammals are more recent.) This is the same theory as (1), but allowing a longer timescale.
3. Detecting this predator is more important to this prey animal than ambushing this prey animal is to this predator. (For example, maybe reindeer are primarily threatened by polar bears, but polar bears mostly eat seals.)
I can see UV light, that purple light from some nightclubs. Is that not UV light? Partially? Can't all humans see it? If all humans can see it, what is the evolutionary hypothesis to explain it? I'm lost in my ignorance someone please help lmao.
Those lights (like most lights) give off a broad range of frequencies. The blue / violet parts that humans can see are by definition not "ultra"violet (beyond the visible spectrum). Even if we could see those frequencies, not much would be needed to explain it other than it helps us see certain things / under certain conditions better.
No, what you're seeing is the lower end of visible light that's also emitted by the uv lamps. They're emitting a lot below 400nm that doesn't pass through your lens. Unless you've had surgery that removes or thins your lens.
Letting uv in is bad in general because it's very damaging. The evolutionary question is rather what benefit the reindeer get that overcomes the drawbacks of increased retinal UV exposure.
I love when articles and knowledge like this surfaces. It adds color and makes our world so fascinating. We really should protect our planet so that future generations can continue to learn and evolve from the wild parts that took thousands of years to develop these unique traits.
Cats can too. Zenny Optical sent me a purple laser to show off their UV blocking technology (I guess it blocks a wide spectrum) and my friend's cats go wild for it. I think it's much brighter to their eyes than mine.
68 comments
[ 3.0 ms ] story [ 145 ms ] threadThis would suggest all reindeeer emit UV light form their nose which they use to communicate with one another.
https://en.wikipedia.org/wiki/Rudolph_the_Red-Nosed_Reindeer
Well, all the childhood cartoons show Rudolph’s nose glowing red.
Of course, with a bright glowing red omnidirectional light source directly in front of the eyes, it’s a bit strange he or anyone else in the sled could see where they were going!!! (Nobody talks about that)
> The reindeer is the only mammal with a color-shifting retroreflector behind the retina and the only ruminant with a lichen-dominated diet. These puzzling traits coexist with eye fluid that transmit up to 60% of ultraviolet (UV) light, enough to excite the cones responsible for color vision. It is unclear why any day-active circum-Arctic mammal would benefit from UV visual sensitivity, but it could improve detection of UV-absorbing lichens against a background of UV-reflecting snows, especially during the extended twilight hours of winter. To explore this idea and advance our understanding of reindeer visual ecology, we recorded the reflectance spectra of several ground-growing, shrubby lichens in the diets of reindeer living in Cairngorms National Park, Scotland.
Ruminant (i.e.: animals that ruminate) is one word I didn't know in English yet but has no simpler synonym: the thing that cows do where they eat their food multiple times. Apparently reindeer are ruminants.
Lichen is another word that I didn't know other than from Minecraft. The actual definition is this (Merriam Webster): "any of numerous complex plantlike organisms made up of an alga or a cyanobacterium and a fungus growing in symbiotic association on a solid surface (such as on a rock or the bark of trees)".
Now, if someone could shed (UV?) light on why the paper's title is chosen the way it is (how is this useful to anyone? When you get this as search result, how're you gonna tell whether this is relevant to what you're looking for? Why not use the title that the HN submission¹ used?), I'd be rather interested
¹ "Reindeer can see UV light" at the time of writing
That sounds like there is still a better title possible a la "Reindeer's UV sensitivity allows them to see lichens better", rather than just making some pun that reduces the information to "something about reindeer in Scotland"
FWIU if you feed land cows seaweed it reduces or eliminates their methane output.
FWIU=From What I Understand; KNF=Korean Natural Farming; JADAM seems to be an uppercase-stylized brand name from what I can tell after some searching (https://en.jadam.kr about page: `He established JADAM (meaning "People that resemble nature") in 1991, and opened website www.JADAM.kr`)
stop it!
Do you know what part of the UV spectrum you can see?
Edit: hmm, and the article's abstract says that reindeer' eye fluid is 60% transparent to UV (I assume that means "60% at the average thickness/depth of a reindeer eye from lens to retina"). That sounds like other animals' generally does not. Does humans'? I guess it must if you're seeing it, or you have special eye fluid!
I only realised one day when I noticed that some kinds of lights looked really dark through my glasses but really bright when I took them off.
UV LEDs are the worst offenders for this as their spectrum can be all over the place even due to QC-passing manufacturing defects.
https://sci-hub.se/https://doi.org/10.1016/0042-6989(92)9016... ("Scotopic spectral sensitivity of phakic and aphakic observers extending into the near ultraviolet")
It looks like it's basically the entire ~315-420nm range. And, we normal/phakic people are technically sensitive to all of those wavelengths too—they're just very heavily, not completely, attenuated by lens absorption. Your relative sensitivity is greater by a factor of maybe 10,000, at 350 nm.
If you can see that unreflected light you have very unusual sight powers.
I don't now if this is even possible, but someone up thread claims they can do it.
UV bulbs look bright purple to me. They are so intense, I can barely even look at them directly. I always thought they were called black lights because they do not appear to light up a room (excepting materials that fluoresce under UV light); the UV light itself is very bright, but everything else stays almost as black as if there were no light at all.
I don't think I can see UV light, though. I don't see UV patterns on flowers that have them, for example. I think I am just seeing some violet light that UV bulbs also release, and maybe it feels so bright because the invisible UV stings my eyes.
That's because they emit a bit of violet light too
> maybe it feels so bright because the invisible UV stings my eyes.
Afaik the problem with UV is that your eyes don't feel them immediately, the pain comes hours later
> "Reindeer is the European name for the species of Rangifer, while in North America, Rangifer species are known as Caribou." The word reindeer is an anglicized version of the Old Norse words hreinn (“reindeer”) and dýr (“animal”) and has nothing to do with reins. The word caribou comes through French, from the Mi'kmaq qalipu, meaning "snow shoveler", and refers to its habit of pawing through the snow for food.
Reindeer have a bunch of subspecies. And there is argument if there are one species or six. Caribou are American and reindeer are Eurasian.
What? That's like saying that cauliflower and cabbage must be literally the same plant.
Reindeer and caribou are differentiated by which continent you find them on. To the extent that it's difficult to walk from Canada to Norway or Siberia, they will have associated genetic differences.
> Cauliflower is one of several vegetables in the species Brassica oleracea
clicks on the latter
> Brassica oleracea is a plant species from family Brassicaceae that includes many common cultivars used as vegetables, such as cabbage, broccoli, cauliflower, kale, Brussels sprouts, collard greens, Savoy cabbage, kohlrabi, and gai lan.
I'm sorry, what?! All the same species? What's the point of calling something a species if it's a different plant or animal! That's like grouping cats and dogs as the same species called Quadlegs Adorables
More seriously, goes to show how little I know about this. Thanks for pointing out how silly a thing it was for me to be surprised that there are different words for the same animal .. when it's not actually the same animal/plant necessarily! I did not know this was a thing. I did hear about definition problems and proposals of "when it can produce viable offspring" or something, but they didn't say that cabbage and cauliflower produces viable offspring which would 180° change my idea on whether that's a useful lowest taxonomy class.
> it's difficult to walk from Canada to Norway or Siberia, they will have associated genetic differences.
I was surprised about that indeed, but less so now that I know that "one species" != "scientific way of saying 'one animal/plant/thingy'"
There is a lot of essentialism that went into initial efforts at taxonomy and a lot that people believe instinctively that they bring to their own modern understanding of it.
By now it is agreed that the correct use of taxonomy is to classify organisms in groups according to common descent from earlier organisms. This was not true as recently as the 1980s, when my mother's college biology textbook included a "teach the controversy" section explaining that that was one approach to taxonomy, but there were other approaches that also made very good points. [Editorial note: there were other approaches, but of course it isn't true that they made good points. They made points like "it's important for each taxon at a given level to contain the same number of species as the other taxa at that level".]
Anyway, once you lose the essentialism, you discover that there is no way to determine what label ["kingdom" / "class" / "genus"...] should be given to a taxon. [= a group of organisms sharing common descent from an ancestral organism.] So you see that divisions between taxa that are important, but that don't match up to traditional boundaries, are given names like subspecies, subfamily, and infraorder.
You might consider why you think it's absurd to unite the categories of "cats" and "dogs", but you see no problem uniting "dachshunds" [tiny and oblong, aggressive, like entering burrows to hunt] with "newfoundlands" [huge, affectionate, like rescuing humans from water]. Just the size differences are such that a female dachshund is unlikely to be able to breed with a male newfoundland. But also consider that rescuing drowning humans is such an important part of the newfoundland lifestyle that they have webbed feet.
I know many articles like to have funny titles. I wonder if this might start to change as people start to use AI more to go through 100,000 journal article titles to quickly see which ones may be useful to their research.
I was already wondering if the ability to search abstracts (and modern engines are pretty good at matching synonyms as well unless you "quote" the keyword), and the displaying of excerpts below each title (like any web search engine does), is what makes the current situation workable.
> White wolves are well camouflaged on white landscapes; unless the prey are sensitive to UV light. It is an appealing hypothesis, but wolves in circum-Arctic habitats subsist on a variety of ungulate species––moose (Alces alces), muskoxen (Ovibos moschatus), roe deer (Capreolus capreolus)––which predicts similar selective pressures on their visual systems (Dominy & Harris, 2022). Studying the eyes of these animals may prove rewarding but, to date, there is little indication they share reindeers’ distinctive visual abilities.
To explain the UV vision of some prey animals as an adaptation to the fact that their predators are otherwise difficult to see, you'd need an additional assumption along these lines:
1. UV vision is a recent development in the prey animal. Eventually the predator will develop UV camouflage, but this just hasn't happened yet.
2. UV camouflage is inherently difficult. (Might be true! This is the generally accepted theory for why insects, reptiles, and birds can be blue, but mammals can't -- mammals are more recent.) This is the same theory as (1), but allowing a longer timescale.
3. Detecting this predator is more important to this prey animal than ambushing this prey animal is to this predator. (For example, maybe reindeer are primarily threatened by polar bears, but polar bears mostly eat seals.)
Letting uv in is bad in general because it's very damaging. The evolutionary question is rather what benefit the reindeer get that overcomes the drawbacks of increased retinal UV exposure.
Dogs are famous for this and researching it just now I see that dogs have a tapidum lucidum and we know they are mammals, sooo…