5 Funky Little Elements of Evolution You Can Spot on Your Own Body

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I'm going to go out on a limb here and say that if you're reading this blog 99.9% of you believe in human evolution.

But if - for some reason - you needed convincing further, there are a number of very cool little clues to our evolutionary past that you can see on your own bodies. In fact, to show you how easy it is to see, I'm going to do a show and tell of my own!


Is this a gang sign? Am I in a gang now?
1. The Palmarus Longis Tendon

If you lay your arm on a flat surface and touch your little finger and thumb together, 85-90% of people will see a little tendon spring up in the middle of their wrist. If you're having trouble seeing it, tilt your hand towards yourself...still nothing? Well feel special, because it looks like you've evolved out of that trait naturally.

Here's mine. Please excuse the creepy E.T hand contortions: smalls wrists and flexible palms do that for ya.

This tendon attached to the Palmarus Longis a now relatively redundant tendon in your arm that once upon a time helped you climb about in trees. You see longer more pronounced tendons in lemurs and small monkeys, and shorter or weaker tendons in apes that spend more time on the ground than in the trees. There's no real signifier that this helps with grip nowadays if you have it.


2. Lactose Tolerance

Do you remember the Little Britain episodes with the 'Bitty' grown man who still breastfed? Do you remember how uncomfortable that was to watch? Well, as far as the majority of nature - including humans- are concerned, drinking any kind of milk as an adult is just as unsettlingly unnatural. 75% of adults on the planet have a natural gene that shuts down the production of lactase, making digestion of milk products difficult. In northern Europe, however, anything between 80-100% of people can digest milk products just fine. Because of Eurocentric Colonialism and the pervasive spread of 'Western' culture as being somehow normative, nowadays the majority of people take the consumption of milks, cheeses and yoghurts for granted as natural when, really, it's an aberration.

Seriously. Look at that divide. 

The ability to continue generating lactase as an adult, which allows the body to break down milk products, was a mutation that happened around 10,000 years ago to people in Northern Europe and some people in equatorial Africa. It's uncertain as to why it developed, but some theories have it that in the colder climates of the green areas in the map above, the ability to consume milk products conferred an advantage. These duller environments meant that people couldn't naturally absorb as much Vitamin D from the sun, which is vital for bone development. Lactose products are good alternative sources for vitamin D due to the calcium so from an evolutionary perspective it's likely that people with it who consumed milk were healthier. The spread of the green to other far flung countries were a product of colonisation by milk-loving europeans. Evolution before our very eyes from some freaky gene and some hungry guy or girl who thought drinking milk would be worth a try.

Living in England and being of British heritage, I can digest lactose just fine. I drink pints of the stuff - thank you freaky ancestor!

Huzzah!



3. Goosebumps to the Cold and Strong Emotions

Ok, I admit it. I stuffed my arm in my freezer for five minutes and didn't manage to get good enough set of goosebumps to photograph on my phone because: summer. But you've all had 'em.

Goosebumps, as most of us know, are leftovers from when we were covered in fur. Despite some modern beauty standards (*cough*) all of us are still covered in hair, top to bottom, but for the majority of the population it's fine and doesn't serve as much use for keeping us warm as it used to. Nevertheless should we get cold the cells at our hair follicles will stiffen and make it so that our hair rises up. When we had more fur and thicker hair, this would create air pockets which would become an excellent insulation.

However one thing you often don't hear about is an explanation for why we sometimes get goosebumps when experiencing a strong emotion. You may get them when you're scared, or when experiencing something so beautiful/ ethereal that it's oddly unsettling at a physical level - like a beautifully sung piece of opera music. (For me, being the dork I am, I got goosebumps when I heard the human and synth-enhanced high notes of the Diva Pavalaguna song in the Fifth Element for the first time). 
It is thought that these serve a similar function - they were from when you puffed up your fur - but instead of being for warmth it was instead for defense. Often when an animal is scared or uncertain it might puff up it's fur to make itself look bigger and more threatening while it processes whether to fight or run away. This response filtered down to the present day when the sudden intensity of an emotion locks us back into that primal fight or flight response of uncertainty and our hairs puff up in defense. We may not feel actually at threat, but the adrenaline response triggers the goosebumps.


Ah, noble Google Image Search. Where would I be without you?



4. Ear Muscles and Shapes

In most ears there are a set of three muscles that lay against them and serve little function nowadays, but for the approx 15% of the population who can wriggle their ears. This awesome party trick is a leftover of evolution from when, as small mammals, we had larger ears. The interesting part is that they're still actively in use. When observing the movement of these muscles even in individuals who can't move their ears, they found that they automatically react to audio stimulus. If there is a sudden noise the muscles leap to activity, and by studying the reaction of the muscles you can even tell what direction the sound was made in. Pretty neat.

Another interesting feature left over by evolution is "darwin's tubercle". These are little bumps that occur as a thickening of the in the outer rim of the ear, which are leftovers from some animal ear shapes - such as the pointed ears of a baboon. Taking a look at my own ears it was a mixed bag - while my left ear was completely thin and rounded my right ear might have a very faint bump. Evolutionary leftovers or just standard variation - who's to say? Have a look at your own and see :)

Piercings optional.


5. Your Third Eyelid

The vestigial third eyelid in humans is one of our most interesting evolutionary leftovers because they are most often found fully formed in birds, reptiles and amphibians. In other words, they prove a common ancestor waaaaay back.
This is called the Nictating Membrance or the Plica Semilunaris and is located in your innermost eye where there is a fleshy flap that takes up a small corner of your eye.

#NoMakeupSelfie

 Back in the day, these would be semi-transparent eyelids that swept vertically across the eyeball to help keep out debris and to keep the eyeball clean. Oddly they can still be found working in some primates, whereas others - like the chimpanzee - are like us in that they are entirely out of use. Here's what they look like when they're fully functioning:




So there you have it. Your body is a history book, so make sure to appreciate it!

Finally, I leave you with an equally awesome and hideous curio of the internet; What Humans Would Look Like If They Evolved to Survive Car Crashes. You're welcome.



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Stay curious!


Sources
- Vox via IFL science via tumblr
- Encyclopedia Britannica
- Wikipedia
- Live Science
- Slate.com
- Oxford Univeristy press
-Scientific American

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