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. ♪♪♪

100 thoughts on “Abilities Evolution Took From Us”

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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”!

  8. 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? 😂

  9. 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 !

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

  11. 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 ???

  12. 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???

  13. 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…

  14. 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.

  15. 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?

  16. 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.


    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.

  17. 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

  18. 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

  19. Right because wings or extra stength would not help something survive. Really there is no evidence that animals are all related. Intelligent design, a much better theory, clearly indicates that animals were created separately.

  20. Ancient Chinese Proverb


    literally translates as
    "animals compete nature selects, suitable ones survive on"

  21. I do believe we can sense pheromones, it's just we are overloaded with them daily to notice them. While on deployments where I was mainly surrounded by men who were not always well maintained, I was able to notice the fragrance difference of a normal daily woman and an aroused woman. My biological reaction surprised me which taught me to get out of the area quickly (married). Lol.

  22. Evolution of eyesight: from
    Blind to very very gradually to full sight. While the species is totally blind is how will it catch his meal? How will defend itself from predators for hundreds or maybe thousands of years?

  23. There is NO SUCH THING AS EVOLUTION!!!! IT NEVER HAPPENED AND NEVER WILL!!! There is Not enough Time EVER to have what evolution says happened to ever happen.

  24. Why its called natural selection , How evolution is selecting them ?
    Cant we just state it as " Traits thats were not able to help species better survive in nature , these species simply wiped out , to those with better traits to help in survival.

  25. My jacobsens organ functions just fine tyvm. I can smell the musk's of various animals, pheromones, even female menstruation. This trait is not lost in the group of humans with significant neandertal dna. Slight electrical fields are aguably sensed by a small number of people as well. We just give it ridiculous names and discredit what we don't understand. The human brain is capable of every trait of every living organism and possibly more. Don't sell yourselves short. What do you think the large percentage of the brain we don't understand or use is for? Why can some people do what others can't? The truly intelligent being realized it knows almost nothing. Once we realize the miniscule scope of our understanding of the universe and our own species then we begin to truly understand how much there is to know. Almost everything. Most claims of knowledge turn out to be nonsense theories. In other words the only thing we know is how little we know. So anyone who claims to know it all is a fool.

  26. Humans have been born with gills, horns, fins and webbed digits, single eyes, tails, fur, scales, you name it and this is a fact of science. Therefore it stands to reason that human dna also contains the DNA of other fauna , maybe all of it. and for all we know possibly even Flora and mycos. This being the case perhaps all life contains all the building blocks of all other life, the switches of the DNA strand being flipped on and off in certain sequences being the deciding factor of what form it will take. This would suggest endless possibilities for combinations of abilities and traits, even genetic memories and evolutionary advancements of both current and defunct species. Combine that idea with how little we know about the human brain and it's functions and abilities and you can see that what some people view as impossible is logically possible, even probable. Brain scans in people with odd abilities show activity in parts of the brain we don't normally see it in. What does this say to you? Is it crazy? Or is it to be expected? Past lives? People who don't need sleep? People with esp? A third eye? Monks with ability to drop their hearts and breathing to a slow almost undetectable rate? People who can dive exceptionally deep and for long times? Regeneration? What else is possible? Is it easier to not believe? How many theories have been proven wrong after being accepted science for a long time?

  27. we still have armpit hair, which is gross, disgusting and useless. We even use perfume to mask our body odour now. So when ARE WE GOING TO LOSE ARMPIT HAIR?

  28. ATTENTION : I AM pro evolution.

    Now that being said, since there is such a debate with anti-evolutionists, why don't we grab some chimps with different lineages and simulate the environments that forced our own evolution? I am aware that it would take a very, very long time for it to take place, yet I see it as having many benefits for science.

    Anti-evolutionists often remark that if we evolved from apes, why are there still apes? Why aren't there also other species of homonids since there are primates that seem to have lasted relatively unchanged over time? Yada yada.. I am also sure there will be people concerned about the rights of the chimps that would be in this MULTI generational experiment. As there should be people concerned and asking questions. There should be people concerned with the welfare of these animals. YET… there are solutions to that as well. There is an island already full of chimps that were "retired" there after labs were finished with them. We could either introduce things and situations into their environment that we believe spurred our own evolution (Opportunity to harness fire, meat based diet, need to become bipedal due to predators ect.) That, or we could choose chimps from that island that don't have communicable diseases and what not, and relocate them with other chimps. We could use cloning as a method of obtaining the chimps needed for those worried about the now living chimps welfare. I'm not in any way suggesting we do terrible things to these animals. Just isolate them from other chimps and continuously introduce situations that we believe helped evolved us.

    So what are y'alls opinion on this idea? Do you think it would even work? Please try keep the hate speech to a minimum, I truly hope I could get some serious feedback to this theory. 🙉🙈🤭

  29. Excellent video, but I just wish you had also mentioned photolyases. They are a MAJOR loss shared by all placental mammals – the very reason we get sun burns and skin cancer. Maybe a future episode on that?

  30. I really like this host. He’s got a calm, smooth voice and seems to not be uncomfortable on camera. Very enjoyable video! Thanks for posting.

  31. Humans are experiencing a devolution as a direct consequence of our drive to make everything easy and divorce ourselves from our natural origins. People still have a 3rd eye, it is nothing more than a shadow of what it likely once was and though it does not pierce through bone, muscle, flesh or skin in a physical way it is what we come into contact with when we explore ourselves from within. We likely all have certain ineffable experiences that feel too real to be dreams yet we either keep them secret or relegate them into socially acceptable boxes. In a certain state of calmness and stillness I can, at times, see a shadow like version of the environment around me, including my hands and feet. I have no mental illnesses, I don't lie and I don't need any drug to achieve this. It is very subtle, like my brain is mapping my environment based upon a perception that is like an eye but not quite. It reminds me of ultrasound imaging. It is a state that can be shattered by the most basic of distractions, it is very fragile and I think that's why a lot of people never experience it or don't want to try and describe it if they do. It is a remarkable mystery to me and it makes me wonder just what exactly we have lost and what that could teach us about ourselves and the direction that we are heading in?

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