Humans Could Have 3 Eyes but Lost One Over Time

Parietal eye or third eye. One of the features we lost almost 250 million years ago. If you take a closer look at animals like frogs or lizards, there’s a small dot somewhere between their eyes. It’s not just a random dot but an actual organ. Scientists claim it’s some kind of a sensor that detects daylight. 

Not just that, it produces melatonin, a special hormone that regulates our biological cycles such as body temperature, reproduction, and sleep. They noticed this eye gradually became smaller over time, which means evolution realized it’s a feature animals don’t actually need. Maybe it happened because cells in our normal eyes became efficient enough, so we didn’t need one more eye to sense how long the day is going to be or when we should sleep. Also, more and more animals were becoming warm-blooded with time, which means they were able to regulate their body temperature better. We have part of the organ even today, but in the form   of the pineal gland in our brains. Still in charge for melatonin. Either way, bye-bye third eye! There’s a gene called GULOP. With it, our ancestors could produce their own vitamin C. Not in a way they can set up a stand and sell it, but enough for the body to use it.  Around 60 million years ago, the gene kind a stopped working. Not randomly; our ancestors probably started getting enough of vitamin C with fruit they ate. Some of our very, very distant primate cousins that took a whole new direction in a family tree,   such as lemurs, can still produce their own vitamin C. At some point, evolution decided they   needed it, while we didn’t. It’s not just us, our side of the primate family tree also doesn’t need   it anymore; monkeys, apes, tarsiers. Bye-bye, GULOP too, we have lemons and oranges now! Our body would lose lots of energy if it had to deal with all those traits our ancestors used to have, so it kind a deactivates those we don’t need anymore. Let’s say, electroreception. It’s   the ability many amphibians and fish have. For example, the electric eel uses this feature to   detect prey when the water is murky, communicate, or as a navigation system. Humans and our land cousins lost this feature because electric current can’t flow through the air that easily. Then, there’s this thing called Jacobson’s organ. It’s found inside the nose and has a purpose to sense pheromones and odors. A snake flicks its tongue, cats and horses make those weird faces… They all use Jacobson’s organ. We also have it, but it doesn’t quite seem to work. It doesn’t send or receive signals from our brain,   and scientists think we lost the ability to use it over 20 million years ago. As human habits and the way of life changed over time, we needed bigger brains. Scientists have   skull remains of our ancestors from different periods, so they’ve realized our brain got way bigger over the last 3 million years. We needed to think of ways to deal with climate changes,   big predators chasing us, finding some new, nice food… Yup, the brain grew for a reason. Food had a huge impact on our evolution. For instance, animals that only eat meat lost their sweet taste receptors because, well, they gave up on dessert so didn’t need those kinds of genes. Humans are omnivores, so we’ve always had a well-rounded set of receptors that could recognize tastes pretty good. These taste receptors came in handy because they could tell our ancestors which foods were   good for them, and which ones were toxic. Some bitter taste receptors stopped working through time since humans have changed their eating habits. For instance, we learned to use fire for cooking, so many plants were less toxic for our bodies. We became sophisticated when it came to preparing food and also learned how to share   information we discovered by communicating and using language. Like in cook books. Ha. We didn’t need all the taste receptors anymore, so our body decided to shut them down and leave those that would come in handy in the future of our species. Phew, luckily we didn’t lose our sense for nice chocolate. Yum! Our jaws have also changed. Our ancestral relatives had way bigger jaws, but since we started eating softer and cooked foods as well as using our brains more, the structure of our head needed some changes. Teeth became smaller too, plus we lost some. Many people may never develop third molars we also call wisdom teeth. They grow between the ages of 18 to 25. We can do without them, but for our ancestors, they were pretty much vital. By this age, their teeth had already become worn out, so third molars were possibly a replacement they needed. We may wonder why exactly we have body and head hair, but scientists wonder why   we don’t have MORE of it. Hair on our scalps is long, a bit shorter on some other areas, and we don’t have hair on the underside of the wrists, palms, and the soles or our feet. One of the popular theories about human ancestors says that, when moving from cool shady forests to the hot, dry savannah, they got a new way of regulating their body temperature. They lost   the fur along the way, which made it easier for them to catch their prey without overheating.   Later, they discovered clothes and fire, which could keep them cozy during the colder times. Of course, there are more reasons for losing fur. Some say without fur, there’s less chance to face lice or other parasites. Other researchers think that, during dry seasons, humans would try to catch prey near lakes and shallow waters. Hair is not such a good insulator in water, so humans lost fur and instead got a layer of fat. 85% of people can’t wiggle their ears. There’s a muscle that surrounds our outer ear,   and scientists believe it used to allow our primate ancestors to move their ears in whichever direction they wanted. That helped them determine where the sound was coming from. After they started living in groups, they didn’t have to completely rely on themselves so they lost that feature. Apes can use their feet as well as they use their hands, thanks to the plantaris muscle in their feet. With that muscle,   animals can grip and do anything they want with objects they’re holding. We also have this muscle,   but it’s underdeveloped and rather useless. 9% of humans are even born without it now. Hic! Hiccups are also one of the evolutionary leftovers humans may have gotten from their   water-dwelling ancestors. Fish push water through gills, while amphibians gulp air.   That’s something mammals don’t have wired in their brains, so this reflex can cause spasms of our diaphragm which, in the end, leads to hiccups. When we’re angry, our lips may twitch. That’s also a feature that used to be important for our   species. When they wanted to scare away predators or potential danger, they would bare their teeth,   the same as bears, wolves, and chimps do. Lip twitching is the first step towards it. Many people want to climb to a higher position or sense the urge to lift their   feet when feeling anxious or scared. Evolutionary biologists believe it’s because so many early land mammals used to climb trees when they felt a threat coming. Goosebumps are something we do have, but, compared to old times, they’re useless now. When hairy creatures felt cold, a reflex would contract those small muscles that make the base of hair follicles. That way, the coat was standing up and trapping more air so they felt warm. Today, it’s just a reminder you need a jacket or that nice feeling you get when hearing your favorite song on the radio. All living creatures can trace their ancestry to a simple bacterium from billions of years ago. DNA is that special thing that holds all the information our cells need to know. We all   start as one cell that then grows into trillions of them, until our body is formed. DNA completely   controls our growth, eye color, height, and so many other traits. It’s not just humans; even   snakes have hip bones that say they used to have four legs just like their dear cousins, lizards. Dolphins and whales have some kind of small bones in their bodies   that show they used to have hind legs. Yup, fossil remains say these marine mammals were   once four-legged and walked on land. To be precise, about 50 million years ago. Evolution doesn’t actually track a straight line from species to species. It’s more like a huge tree with plenty of branches where some lead to new ones, a trait there, a trait then, some in, some out, and BAM, some completely new species are there. For example, birds. Who would have thought they evolved from dinosaurs? They even lost their teeth along the way. And, yeah, both seem to be coming from reptiles. Oh, and those nuts over there, that’s part of MY family tree.