Why The Human Eye Is A Design Disaster - Cheddar Explains

[Music] they say eyes are the window to the soul but if human eyes are a window they'd look like this over 24 million adults in the united states have eye issues either you're born with eye issues you grow up to have eye issues or you get so old that your eyes deteriorate into one big issue and it's not just bad vision there's cataracts glaucoma retinal detachment the list goes on and on and all of it makes me squeamish and we aren't alone all of our vertebrate counterparts have terrible eyes as well so why are our eyes an engineering nightmare to answer that question we'll have to look into the eyes of a squid do you suffer from age-related macular degeneration uveitis keratoconus blepharitis corneal ulcers diabetic retinopathy strabismus colorblindness or astigmatism then unfortunately you may suffer from having human eyes 400 million years of evolution has been conspiring against you so let's take a closer look pun very much intended at why our eyes have so many issues this is an eye the sclera is the white part here it's covered in tiny blood vessels and made of tough material to protect everything inside the cornea is a dome of transparent tissue on the outer surface the iris the colorful part of the eye here is a ring-shaped membrane that contracts and expands to let light into the eye the pupil may look solid but it's actually an empty hole that light goes through to enter the inner eye this is the lens it sits right here behind the pupil to focus light light then travels through the vitreous humor before hitting the retina the retina's job is to receive the light and turn it into neural signals the millions of light-sensitive cells that make up the retina are connected to the optic nerve which sends all the information to your brain but here lies the problem our retinas are backwards these are the photoreceptor cells and they're facing towards the back of your head where there is definitely no light the back of the cell which doesn't receive light faces front towards the pupil if every cell is like a tiny camera they're all facing backwards so the photons of light have to travel around the photoreceptor cell to hit the receiving side of the cell i know confusing right scientists haven't been able to come up with a working hypothesis as to why our retinas are set up backwards to learn why let's take a look at organisms that have a front-facing retina cephalopods cephalopod eyes and vertebrate eyes are super similar but they evolved completely independently of one another there are 10 or 12 different types of eyes out there in the animal world but this one the camera-like eye is the most sophisticated the most complicated and also capable of the greatest resolution and we share that also with cephalopod so squids and octopi have the same kind of eye as well pretty much even though they invented it separately this means that nature invented the camera-like eye twice insects arachnids and crustaceans have entirely different types of eyes during the evolution of the cephalopod eye the retinas never flipped inwards which is the logical way to have it and cephalopod eyes have perfectly adequate oxygen and blood delivery to the metabolically active receptor cells but that doesn't answer the question of the backwards retina there aren't any scientifically proven positives so are there any negatives well yeah right smack on top of the retina is the optic disc it's where the millions of photoreceptor cells converge to form the optic nerve it creates a blind spot in each eye we don't notice these blind spots normally because the other eye compensates for it but they're definitely there having a blind spot is unavoidable because of the backwards retina and all vertebrates have it but cephalopods don't because their optic disc and nerve are behind the retina and that's not all a myriad of other eye issues plague humanity because of the backwards retina like diabetic retinopathy 80 of diabetics who have had diabetes for 10 years will develop it in response to a chronic lack of oxygen in the eye the blood vessels around the retina expand and proliferate to increase the blood supply because the blood vessels are on the back side of the retina which is the front side of the eye they get in the way an obscure vision which yikes even more yikes is that to fix it they take a laser and burn away some of the blood vessels so you can see through them again but it isn't just that backwards retinas make our eyes a design disaster another big problem with our eyes is their size one of the most common issues with our eyes is nearsightedness myopia as it's called scientifically is caused by our eyeballs being the wrong size i'm not kidding 30 to 40 percent of american and european adults and seventy percent of asian adults have myopia which is nearsightedness which means they can't see things that are far away because their eyeballs are too long the light coming through their eyes focuses here before the retina but the light actually needs to focus here on the retina which it doesn't do and the backwards retina just makes the problem worse myopia is also a strictly human problem but when we look into the numbers about uh distance vision so myopia losing your your ability to see a distance what we find is that this is a relatively new phenomenon in our species and it began around the middle ages because what happened in the middle ages is that we began to live our lives indoors prior to to that time period uh in the in the history of the west you were outside most of the time day-to-day life you know basically took place outside and so our when we grew up particularly as children as our eyes were growing we were used to seeing existence what happens when you spend the majority of your childhood indoors focusing on near objects is that your eyes do not grow to the right length and essentially they grow too long but what about farsightedness there are actually two kinds one is the opposite of nearsightedness meaning that our eyeballs are too short and the light doesn't focus before hitting the retina the other kind of farsightedness is caused by aging and so to accommodate for very near vision you have to flex and squeeze that lens a little bit and that's what allows us to see up close unfortunately as we age however it becomes more and more inflexible and the muscles that are responsible for pulling that lens uh in order to flex it they just aren't strong enough they're called the ciliary muscles that surround the lens they just simply can't flex it because it hardens as we age and so when this lens becomes so inflexible that it can't be squeezed that's when you lose your near vision it usually begins to set in around age 40. by age 60 virtually everyone has it and what's interesting i've noticed i'm 42 years old and i've noticed that when i read i'm getting farther and farther away from my face in order to read properly and that seems weird like if you want to see it you should bring it closer but i just can't focus on near enough vision because my lens like everyone else my age my lens is getting harder and more inflexible and there's pretty much nothing we can do about that humans have a lot of eye issues because our eyes are so complex but other vertebrates have eye issues too and all of us have worse eyes than cephalopods our backwards retinas are simply bad design and scientists don't know why they evolved that way it might have just been a quirk of evolution in addition in the past few thousand years super sharp eyesight hasn't been a trait that has been sexually selected for that means that when your ancestors were getting together great-great-grandma didn't really care if great-great-grandpa could see far away your body might have been a disaster but you were smart so that was another way you could contribute and succeed and that's not really true for any other animals i can live in a very different way from someone else and we both succeed and that's really the power of cultural evolution and cultural evolution has taken biological evolution out of the driver's seat unfortunately there's not much we can do about it now our retinas are backwards and they're not changing anytime soon thankfully 20 20 vision isn't necessary to survive or have a happy life but if any sentient cephalopods roll up asking you why you're wearing glasses now you know what to tell them what do you think of the bad design of our backwards retinas let us know in the comments make sure you like this video click subscribe and don't forget to ring the bell for post notifications we'll see you next time

Channel: Cheddar

Views: 434,791

Rating: 4.8803411 out of 5

Keywords: Cheddar, cheddar explores, cheddar explains, explainer, human eye, design disaster, evolution, eyeball, eye, glasses, vision, myopia, nearsightedness, farsightedness, cataract surgery, retina, reversed retina, squid, squid eyes, natural selection, animals with best vision, eyesight, sight, anatomy, biology, human anatomy, octopus eye, ophthalmologist, ophthalmology, eye disorders, bad vision, evolve

Id: fPnYH06VJVo

Length: 9min 8sec (548 seconds)

Published: Tue Dec 01 2020

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[u/cheap_tree]

The interpretation of that verse has changed to “Allah was speaking about the mind” after those defects in human body where found(btw there is way more than just the eye disaster). However, even the brain is flawed with its illogical thinking and beliefs and how can it be easily tricked and deluded (which evolution give an explanation to)

[u/[deleted]]

does islam say that gods creation is perfect if so then that means that this video pretty much debunks it