Abilities Evolution Took From Us

Abilities Evolution Took From Us


♪♪♪ A common misconception about natural selection,
and evolution as a whole, is that it’s essentially a long chain of progress, adding on new features
over and over again. But evolution doesn’t always add stuff. Sometimes it takes away traits too. That’s because natural selection only favors
traits that help an animal reproduce, or survive until it can reproduce. If a trait doesn’t do that, it’s not selected
for. In fact, it might start to disappear thanks
to mutations piling up. That’s known as relaxed selection, because
natural selection no longer maintains the trait. If the trait takes a lot of energy for the
organism to maintain, there can even be a selective pressure to lose it. Human evolution contains plenty of examples
of this — in fact, there’s a whole host of things our distant ancestors could do that
we just can’t anymore. From pheromone signaling to detecting electricity,
here are some weird abilities evolution has denied us. First up: the so-called “third eye.” If you take a look at some lizards or frogs,
you might see something that looks like a small, grayish dot on their forehead. This isn’t a scale. It’s actually an organ called a pineal or
parietal eye. It detects light, and scientists think it
functions as a kind of daylight sensor — a way to keep track of the seasons and how long
days are. It also synthesizes melatonin, a hormone that
helps regulate biological cycles related to sleep, reproduction, and body temperature. Parietal eyes are likely very old. The evidence can be seen in the fossil record,
including the skulls of the long-dead precursors of mammals. It’s an opening in the skull called the
parietal foramen, and in life it accommodates the parietal eye and its associated nerves. But a 2016 study found something interesting. Looking at the skulls of mammal ancestors,
the researchers observed that the foramen — and the eye, presumably — gradually
became both smaller and less common around 245 to 260 million years ago. The researchers suggest its disappearance
is evidence of one of two things. One, cells in the animals’ “normal”
eyes might have essentially taken over the pineal eye’s duty of sensing daylight length
and seasonal change. Or two, the loss of the pineal eye might be
evidence that the animals were becoming warm-blooded and better able to regulate their body temperature. Thus, being able to sense how long the nice
warm sun was out through the top of their head became less useful. Either way, the organ wasn’t as adaptive
as it had been, and the selection pressure to keep it waned. Today, we’ve kept part of the organ around
in the form of the pineal gland in our brains, which still synthesizes melatonin. But we no longer need an extra eye in the
middle of our forehead for it to work. Another ability we lost during evolution is
electroreception. This is the ability of some fish and amphibians
to detect weak electric fields. The electric eel, for example, can use it
to navigate or to detect prey in their sometimes murky river habitat. You can even see the organs responsible for
it in the lateral line on some sharks and fish. While not super common today, it’s found
in a wide array of different lineages, suggesting it might have also been a trait found in very
early vertebrates. However, our ancestors seem to have lost the
system with the transition to living on land. Why? It might have just not really worked as well
in air compared to water. And, again, traits that don’t confer selective
advantages are apt to disappear. Funnily enough, later on, some mammals, such
as platypuses, echidnas, certain dolphins, and maybe others did end up evolving electroreception
again, but through completely different mechanisms. And we’re not totally sure what for. Finally, let’s talk about the Jacobsen’s
Organ, aka the vomeronasal organ. This structure is found inside the nose, and
it’s used to sense odors and pheromones. When a snake flicks its tongue in and out,
it’s using its Jacobsen’s organ. That weird face horses and cats make sometimes? Same thing — it’s called the flehmen response. We have a vomeronasal organ too, but it doesn’t
really seem to work. The topic of whether humans can sense pheromones
at all is kind of contentious. But by the time we’re adults, our Jacobsen’s
organ has no sensory neurons connected to it, and most researchers believe it doesn’t
send our brains any information. And we have a handful of genes that, in other
animals, make the vomeronasal organ work. But in us, those genes are non-functional. As for when we lost it, a study from 2003
dated the inactivation of those genes to around 23 million years ago, about when the great
apes split from monkeys. That might correspond to apes’ visual systems
becoming more advanced, and visual cues becoming more important than scents during social and
reproductive activities. In fact, we might still be in the process
of losing the genes associated with our Jacobsen’s organ — totally at random. Mutations happen all the time in our genome,
altering or deactivating genes, and without selective pressure to stop those mutations
from building up, eventually the trait those genes contribute to can disappear. Natural selection isn’t just a matter of
continually adding on new features. If something isn’t helping an organism produce
offspring, that feature is likely to get left behind in the long run. The reason we don’t have third eyes or any
of these other neat traits is that, in the end, we ended up getting along fine without
them. Thanks for watching this episode of SciShow. If you like learning about why we don’t
have weird electricity-sensing superpowers and want more videos like this one, consider
supporting us on Patreon! You can get started at patreon.com/scishow. ♪♪♪

Comments

  1. Post
    Author
  2. Post
    Author
    Dr. Dragon

    YOU ARE DREAMING! after hundreds of years of agressive selective breeding on dogs, cats, horses, plants, etc, after experimenting on tousands of generations of fruit flies: they still got a dog, a cat, a horse and a fruit fly. Everything reproduces acording to it's kind and always looses information. Never has anyone seen new information being produced. And mutations= scrambling existing information. They are always harmful!

  3. Post
    Author
  4. Post
    Author
  5. Post
    Author
  6. Post
    Author
    boulderbash19700209

    Color detection was also decreased in mamalian. Especially in carnivores, now they only have two colors detector, for blue and green. Even in human, we have color blindness.

  7. Post
    Author
    Elizabeth Moriarty

    Sorry, but we do have a third eye…. well some of us do anyway. It's like that saying, you don't use it- you lose it. So if you can detox your body, decalcify your pineal gland (since the U.S. government loves us SOOOOOOO much 🙄, putting all that fluoride in the water and all), and meditate- there is a very good chance that you may get your third eye usage back. Now, before any fanatical Christians jump on me, PLEASE consider the following information:

    1. The pineal gland is mentioned in the Bible as the way to talk to/connect with God. It states something like (sorry I don't have a bible directly in front of me) that Jacob spoke with God face to face, and he calls that place pineal.

    2. The pineal gland is also called (by scientists) the Spirit Molecule.

    3. The pineal gland releases serotonin during the day, and melatonin at night(this is where your dreams are "visioned".

    4. When you die, the pineal gland releases DMT. Now, when used as a street drug (compared to naturally in your body)- DMT is RIDICULOUSLY hallucinogenic. (But people don't do DMT to get high, they do it for spiritual growth. I have never, not ever, not even once heard of anybody doing it for any other reason.) Now, this can't be proven, but LOTS of research has led me to this conclusion- DMT is released(in my opinion) , to remove the veil/ barrier that separates the physical world, from the spiritual world. You can not live in both worlds just as (stated in the Bible) you cannot serve two masters. Since Satan rules the physical world , some people may want to start decalcifying their pineal gland. The government is destroying this gland with all the chemicals that you are constantly bombarded with. This is not a conspiracy theory. Fluoride, will destroy this gland. When this gland is destroyed, you are stupider, docile, easy to control. And since this also is the place that seats the soul, they either gain power over your soul, or to destroy it ( I really don't know).

    I've gone on long enough, sorry about that. I just want people to open their eyes…..all 3 of them😁

  8. Post
    Author
  9. Post
    Author
  10. Post
    Author
    44 Hawk

    Considering that human DNA only goes back a hundred and twenty thousand to two hundred thousand years ago at most. Most of these dates you're stating has nothing to do with when we lost anything.

  11. Post
    Author
  12. Post
    Author
    kukukachu

    The third eye is real and can still be activated. I believe that mine was activated by jasper, but I can't confirm that. All I know is that I was sitting in a room with jasper rocks and tumbled rocks all around me, reading in a book and all of a sudden my forehead felt funny. It was a tingling sensation between the eyebrows and a light pressure above that. It has now been a month now and I still have the sensation. I looked up information about 3rd eyes and found that the description that was being described was the same thing I was experiencing. The 3rd eye can indeed still be activated, but not everyone is going to activate theirs. I can't say that it has changed me in a way that I know more than anyone else or anything, but I can say that I now feel like I am connected to something…It's really strange and I am excited to keep exploring the unknown and this new chapter in my life.

  13. Post
    Author
    Archer

    There are theories that the skin of Celtic people used to be reddish/copper brown, instead of the pale white that we are today. It is theorized that after migrating 15,000 years ago, from Northwest Africa (Morocco/Algeria) to present-day U.K., they no longer needed the natural UV sunblock and so it has slowly degenerated over thousands of years into what we call freckles today.

  14. Post
    Author
  15. Post
    Author
  16. Post
    Author
  17. Post
    Author
  18. Post
    Author
    RyoPaque Q

    It could be that apes lost their pheromone sense when they gained more walking ability, allowing them to spread out to the degree that they didn't smell each other as often and then because of that they needed to have better eyes to see each other.

  19. Post
    Author
    jmatt4life

    Maybe the traces of a parietal foramen is what I sense when I make myself sleep on nights which I cannot sleep?
    I do sense a red light even though my eyes are closed and eventually melatonin kicks in and doze off.

  20. Post
    Author
  21. Post
    Author
  22. Post
    Author
  23. Post
    Author
    Del Bel

    Hey! Great video as aways! But a little correction to be made:

    The lateral line in modern fishes is mostly a water pressure, and not a eletric field, sensor.

    From your own sources:
    "Electroreception is absent in most modern fishes, with the exception of two independently evolved lineages of teleosts, which include the catfishes and the notopterid knifefishes of Africa."

    So a golfish does not have a eletric-sensing lateral line.

    But yes, the ancestor of vertebrates probably had eletricfield sensors associated with the lateral line (but not along the line), so the overall point of the video still holds.

    I'll leave this here: https://jeb.biologists.org/content/216/13/2515

  24. Post
    Author
  25. Post
    Author
  26. Post
    Author
  27. Post
    Author
  28. Post
    Author
    killer oblivin

    You do realize that many people at least in America are evolution deniers my point is that that thumbnail gives ammo… Even if that ammo is easily clairifyed.

  29. Post
    Author
    Israel Vazquez

    It is a common misconception that evolution is a proven truth. It's mostly just baseless assumptions and presuppositions

  30. Post
    Author
  31. Post
    Author
  32. Post
    Author
  33. Post
    Author
  34. Post
    Author
  35. Post
    Author
    Brandon Payton-Coons

    Evolution isn't real. Somebody try to explain this; How could we evolve to a point to believe in God, without any outside information being input into us? How would evolution, alone, bring us to the point to believe in spirits, without any outside info coming into our minds.

  36. Post
    Author
  37. Post
    Author
  38. Post
    Author
  39. Post
    Author
  40. Post
    Author
  41. Post
    Author
  42. Post
    Author
    Turtle Von Nurtle

    The Lateral Line is a pressure sensing organ, it is not electroreceptive, electroreception goes through related pits that are on the shark/fish/amphibian's (pretty much only salamanders in larval or neotenic form) face.

  43. Post
    Author
    penguins forall

    We also lose traits through extinction events where by the spread of useful genes are cut off from an otherwise surviving population who happen to have some other gene that helped them survive.

  44. Post
    Author
    ShadowFoxSF

    We don't have a 3rd eyelid (nictitating membrane) so we can't blink without shutting our eyes…
    We can't swivel our ears…though some like me cam wiggle them a little.
    We can't bite as hard as many apes and our ancestors.
    But the ones in this video are about much older traits. I approve.

  45. Post
    Author
  46. Post
    Author
  47. Post
    Author
  48. Post
    Author
  49. Post
    Author
  50. Post
    Author
  51. Post
    Author
    neighbor . - J -

    Lots of conjecture, loose extrapolation, and weak hypothesis here…

    Yet you talk so matter of factly, why is that?

    Sounds a hell of lot more like rough guesses based on other barely connected evidence. Far from conclusive theory.

  52. Post
    Author
    Emily Lochore

    Look at all these abilities that aren’t really that useful but would be cool to have. I need my vaguely convenient third eye and electromagnetic receptors.

  53. Post
    Author
    Rubicel Trejo

    It’s fascinating to see how humans have evolved to achieve the highest chance of survival. What’s ironic is that our intelligence, which has brought us to this point is what’s going to bring our demise if we keep turning a blind eye to our environment. I sadly doubt we’ll be able to evolve as a species to realize that

  54. Post
    Author
  55. Post
    Author
    Xsell Epoch

    This is a great example of the fallacy that anything “natural” must inherently be “good”, so we should just let evolution take its natural course, and any attempts to meddle must automatically be bad. Humans should take control of their evolution with science, not settle for “barely good enough”!

  56. Post
    Author
  57. Post
    Author
    Pedro Vieira

    We still have whatever traits we had on the past, only very diminutive.

    Besides time acting in "favour" to lose them, society also did its part. As time past, people who had certain "skills" wouldn't need them (and therefore train them) and they wouldn't pass them to the offspring. That's epigenetics, I believe.

    That being said, we only have remains of such traits (biological vestiges), like the appendix.

    But many people believe that the pineal gland has more than meets the eye… Get it? 😂

  58. Post
    Author
    Jerome Rovnak

    Food Poison = You Eat and Drink Chemicals , for $ This is affecting Your Evolution . Egos and Emotions Damaged to Self Distrust and Disunity . Just Like Being Farmed By Demonic Creature$ You Get What You Pay For !

  59. Post
    Author
  60. Post
    Author
  61. Post
    Author
  62. Post
    Author
  63. Post
    Author
  64. Post
    Author
  65. Post
    Author
  66. Post
    Author
  67. Post
    Author
    Michael Watts

    We do still have a melatonin producing third eye. We can sense electricity. Some people are just more sensitive than others

  68. Post
    Author
    Hajar Renate Midbrød

    why hasnt natural selection gotten rid of stupid ???? since november 8 2016 …AKA doomsday …AKA presidential election ) stupidity has increased in frequency …what gives evolution ???

  69. Post
    Author
  70. Post
    Author
  71. Post
    Author
  72. Post
    Author
  73. Post
    Author
    Dichtsau

    sorry, point #2 is simply WRONG. we humans still do have electroreception – or how do you explain that ppl feel a weird electrical pressure in their brain, comparable to a sour muscle, if they're surrounded by strong electrosmog for a long period of long intervalls with short breaks???

  74. Post
    Author
    Omar Bassam

    I’m studying medicine, and I won’t believe in any case that all of this has came by evolution and chances …this video is just time wasting…

  75. Post
    Author
  76. Post
    Author
  77. Post
    Author
    blocksterz

    Thankfully the Jacobsen organ gone .. imagine heading to work in crowded metro smelling hundreds of stacked pheromones

  78. Post
    Author
  79. Post
    Author
  80. Post
    Author
  81. Post
    Author
  82. Post
    Author
    M.J H

    Natural selection has been excedingly rare throughout evolution.

    Nearly all evolution can be attributed to artificial selection dictated by interactions with other organisms, not the environment. I will provide two examples.

    The first is Darwin's finches. Often these birds are used to explain Natural selection, however the natural enviornment itself had little to do with the evolution of their beaks. It was in fact the fruits of the trees and plants that dictated who would survive long enough to have offspring.

    Thus their selection was dictated by another living thing and so is classified as Artificial and not Natural.

    The second is leaf cutter ants and the Acacia tree. Where the tree has proteins within it that cause the leafcutter ants to become more aggressive and protect the tree from herbivores and beetle larva wishing to devover it. This artificial selection has determined the evolution of the ants and the tree, promoting adaptations that favor both.

    There are an infinite number of examples I can place here.

    Furthermore you will find it quite difficult to produce examples of truly natural selection within evolution. The few I know would be catastrophic events like asteroid impacts or volcanos.

  83. Post
    Author
  84. Post
    Author
  85. Post
    Author
  86. Post
    Author
    Chananiah Mordecai

    I think in western society intellegence will get evolved out, because people with greater intellegence have fewer children, and people with lesser intellence have more children. So western society will get dumber and dumber as time goes on. Maybe that's what happened to Rome?

  87. Post
    Author
    Marc Abelha

    TL;DR
    this video develops 2 misconceptions. I want you to consider 2 points below, having in mind traits cost, sometimes heavy cost.
    1) While relaxed selection is a thing (0:25), evolution selects negatively BECAUSE the cost is, in some way, detrimental (0:32). Somehow the video touches the point, but disregard it for the rest of the arguments presented.
    Sad thing.
    2) Loosing a trait forces the development of a better adaptation, so we loose it not because it lost value (1:49 and 3:30), but because it favored a better way to cope with the same old necessity (4:08) with further benefits. The change was also costly, but payed off.

    Detailed.

    Any trait, any gene or physiological interaction has a cost, undergoing negative and positive selection pressure AT THE SAME TIME. This is an axiom for biological systems, a philosophy if you like. Utterly underestimated in the video.
    1) We don't loose traits because they have low or no value.
    See, traits (phenotype, and its genotype distribution) always have a cost. Some have a high cost in physiology, ecology, etc. A pin-point example: Bacteria have plasmids, small circular DNA chains separated from the big genome that encode for antibiotic resistance. They add this heavy cost in extra DNA (negative pressure) produced because it has value (positive pressure). But once the environment doesn't have antibiotics anymore, random bacteria that lost this plasmid reproduce faster (positive pressure without negative pressure), less time time consumed in DNA replication, less resources needed. Thus natural selection favored the loss of trait, no more antibiotic resistance in the population, cost less for living and reproducing.

    Relaxed selection doesn't affect phenotype frequency in a population, so it has no impact on natural selection. Explanation: a mutation, called recessive gene (mutated gene), occurs in a single individual and has a 50% chance to disappear in the next generation. Even if an entire family has the mutation, further reproduction will loose it because the dominant gene exists in such overwhelming numbers. Google for Genetic Drift why we have recessive genes in high relative number (high frequency). Mutation mechanisms that affect more then one individual do impact, like a DNA virus that, in a contagion process, inserts itself in the host genome causing it to change somehow.

    2) Trait replacement like in 4:08 is tricky: We need, at some point, to have both traits, so that one strengthen (because of net positive pressure) while the other recedes (because of net negative pressure). But they are both complex systems being selected. A system has a core trait or traits, but have marginal traits that connect to other systems, which also undergo a parallel, maybe less selective process. But IT IS NOT a strong trait replacing the older, but rather been strengthened by the negative selection of the older. If the conditions for positive and negative selection continues, regarding costs and value, the systems enter a feedback loop.

    As we can see, the topic is very complex. Consider the process that formed the appendix, a diminished organ functionality was costly, so this entire region of the intestines diminished also, as a core residual trait (immunology) justified its existence, but in a very small tissue with less maintenance needed.

  88. Post
    Author
  89. Post
    Author
  90. Post
    Author
  91. Post
    Author
  92. Post
    Author
  93. Post
    Author
  94. Post
    Author
  95. Post
    Author
  96. Post
    Author
    Arthur Estrela

    We already have superpowers. Instead of imagine having another eye or eletric sensitive organs, just be glad by carrying complexes liver and kidneys, and most of all, the brain. If we were cyclops or something we would wonder how amazing it'd be if we had two eyes and see the world in 3D

  97. Post
    Author
  98. Post
    Author
  99. Post
    Author
  100. Post
    Author
    Harley Toms

    Evolution probably took away our ability to see gods. Maybe ancient humans saw them. Natural selection "thinks" its OK since people believe in an invisible unicorn

Leave a Reply

Your email address will not be published. Required fields are marked *