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Dorsa Amir @DorsaAmir

Evolutionary anthropologist. Postdoc @BostonCollege|@BCVirtueProject. I study the diversity of human behavior from a cross-cultural, developmental perspective.

https://t.co/4wvdKYCXoR
Dorsa Amir @DorsaAmir
Did you know the human body is full of evolutionary leftovers that no longer serve a purpose? These are called vestigial structures and they’re fascinating. (1/8)

Palmaris longus, sisa-sisa kemampuan manusia sebagai primata yang mampu memanjat pohon.


Dorsa Amir @DorsaAmir
Put your hand flat on a surface and touch your pinky to your thumb. Do you see a raised band in your wrist? That there’s a vestigial muscle called the palmaris longus. It used to help you move around the trees. About 14% of us don't even have this muscle anymore. (2/8) pic.twitter.com/ZF3Ta91IGy
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Darwin's tubercle, yang membantu dalam menggerakan kuping.


Dorsa Amir @DorsaAmir
Check out your ear. Do you see this little bump? That’s called Darwin’s tubercle. It used to help you move your ears around. Now that we have super-flexible necks, we don’t need these anymore. (3/8) pic.twitter.com/2OlVWEu6gT
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Tulang ekor, sisa ekor yang membantu dalan keseimbangan badan.


Dorsa Amir @DorsaAmir
Here’s a more obvious one: the tailbone. This is the ghostly remainder of our lost tails, which were useful for balance & movement in trees. We still grow tails as embryos, but then attack and destroy them in the following weeks. Not the most efficient system. (4/8) pic.twitter.com/pmF2lCpnyT
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Manusia ternyata punya "kelopak mata ketiga" yang fungsinya untuk berkedip menyamping seperti kadal.


Dorsa Amir @DorsaAmir
Ever wonder what this little pink thing in your eye is? This is the plica semilunaris. It used to be a third eyelid that would blink horizontally. You can see this in action in the eyes of many other animals. (5/8) pic.twitter.com/0ubMulahA0
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Vestigial reflex, atau merinding, yang memungkinkan manusia untuk tampak lebih besar ketika merasa terancam.


Dorsa Amir @DorsaAmir
Oh, and you know how you sometimes get goosebumps when you’re cold or scared? That’s a vestigial reflex that used to raise body hair to make you appear bigger or trap an extra layer of heat for warmth. Some people can actually do this on purpose. (6/8) pic.twitter.com/uY2zJddguy
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Bayi suka menggenggam jari? Ternyata ada alasannya…


Dorsa Amir @DorsaAmir
Another cool reflex is the palmar grasp reflex. If you place your finger on an infant’s palm (or feet!), they will try to grasp it. Ancestral primate babies would have used this to grasp on to their parents for transport. (7/8) pic.twitter.com/LFpN1ykSug
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Dorsa Amir @DorsaAmir
These are just a few pieces of evolutionary baggage handed down to you from your primate ancestors, among others. Your body is basically a natural history museum! (8/8)
Dorsa Amir @DorsaAmir
A few addendums: Wisdom teeth — yes, though still ~functional for original purpose. Appendix — potentially yes, though it still seems to do stuff (may have been repurposed). Male nipples — though technically non-functional, not quite vestigial. Due to embryonic development.
Dorsa Amir @DorsaAmir
Additional footnote: I think the diagram I randomly pulled off Google Images yesterday isn't as precise as it should be. *This* is the plica semilunaris. pic.twitter.com/nWh4PLoiOV
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Fraser Scott @FJScott3
@DorsaAmir @SteveStuWill LOVE THIS. Somehow a sport science degree allowed me the opportunity to study this for a few months. Best thing I got out of the degree. Beautiful evolution.
Peter Moleman @MolemanPeter
@DorsaAmir Wow, that's interesting. How do you know that they have no function anymore, e.g. the grasp reflex?
Dorsa Amir @DorsaAmir
@MolemanPeter Good question! In most cases, vestigiality is determined by comparing to related animals, considering what function those traits are serving for them, and whether they still serve the same function for us. Check out this woolly monkey to see what this grasp reflex is used for. pic.twitter.com/0JRgo0hZio
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Fernet Bronco @BusterBroncoEsq
@DorsaAmir @MolemanPeter Does help with immediate bonding though ❤️❤️❤️ pic.twitter.com/smvBITb3yk
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Brown @xyogee
@DorsaAmir Very interesting and enlightening. Do other species also carry vestigial structures that we know of? since they'd also be continuesly evolving in new environmental challenges?
Brown @xyogee
@mrmarchee @DorsaAmir No, but in this pic who has the vestigial structure and where ? Elephant or Human?
Frances Ana @snowflakedunord
@xyogee @DorsaAmir I would think so. Whales for example used to live on land and you can still find tiny legs on the big blue whale and some other ones.
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