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1500 questions
19
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How old is the oldest intact DNA?
DNA fragments are known from bone fragments from the Mesozoic, but these don't count. I'm guessing the oldest DNA is recovered from permafrost, but how old exactly?
Gordon Stanger
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What effect does a bat's echolocation have on other bats?
Bat echolocation is a perceptual system where ultrasonic sounds are emitted specifically to produce echoes. By comparing the outgoing pulse with the returning echoes, the brain and auditory nervous system can produce detailed images of the bat's…
M.A.R.
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Where’s the flaw in my proposed TB Treatment?
Ten years ago, I emailed a prominent lung specialist with my suggestion for a treatment for Tuberculosis. His lack of response led me to believe that the idea had no merit whatsoever – but I had no idea what the failings might be. I still don’t and…
Lefty
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Why do humans require vitamin B12 supplementation while herbivores do not?
This question came about from reading the comments of this (very unclear) question, which the author did not properly clarify.
Vegans are often recommended to take vitamin B12 supplements, as the vitamin is not present in sufficient quantities…
March Ho
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Was the recent "conservation hunt" of a black rhino supported by science?
CNN recently covered a sanctioned black rhino hunt in Namibia by Texan Corey Knowlton, who bid US$350,000 for the license. In the story, he claims that the hunt was actually supporting conservation of the critically endangered species, as they were…
MattDMo
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Why is the brain dependent on glucose?
The strict dependence of the (human) brain on glucose has always been puzzling to me. While ketones can substitute for a portion of the brain's energy needs, it cannot substitute completely: blood glucose levels below 2--3mM somewhere causes serious…
Roland
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What kind of fruit is this?
Just spotted this fruit while walking to school. It's the size of a small coin.The taste is almost sour and tangy and somewhat sweet (I only tried one of them and very little of it). I admit, I've never seen it before. Does anyone know what this…
darksky
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Are there single-celled organisms that have evolved from multi-cellular ones?
I'm reading this paper about transmissible cancer cells in clams (Metzger et al. 2015) and I was wondering if there are any single-cellular organisms that are around today that are suspected as having descended from a multicellular organism
My…
C_Z_
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How do birds deal with their eyes drying out at high speeds?
My eyes tear up when cycling at 15 mph, which is nothing compared to bird airspeeds.
Do birds continuously produce lots of tears and blink a lot, or do the eyes self-moisturize from the inside without need of blinking, or are their eye surfaces just…
SuperElectric
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Why can't the brain and red blood cells use fuels other than glucose?
The question is rather straight forward: I have always been curious as to why, but cannot find an explanation online.
I can imagine that the mechanism is different for each, but why does brain tissue and red blood cells use specifically and only…
LanceLafontaine
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Why did humans lose their fur?
The little amount of body hair humans have don't seem to be of much use for keeping warm.
Our Simian cousins on the other hand sport thick furs.
At which point during the species evolution and why did humans lose their fur?
Cleber Goncalves
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Why is green fur not a thing?
In most biomes on earth, and certainly in the most densely-populated, the best camouflage color or pattern for an animal would be a variant of green, so as to blend in with the leaves and grasses of the surrounding environment. Whether predator or…
Nerrolken
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Why do birds move their heads abruptly?
When we humans look around, we pan smoothly from one side to the other. Birds on the other hand seem to point their head in one direction for a while, then abruptly point their head in another direction and stay in the new position for a while. Then…
atmelino
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What is the female equivalent of the morning erection that some men experience?
There was question about what causes "morning wood." It was answered that the erection in the morning is caused by decline of norepinephrine during REM sleep. Which in part allows to prevent uncontrolled urination.
My question is: How does the…
jnovacho
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How does Sodium Valproate cause neural plasticity
I have been reading a fascinating paper: Valproate reopens critical-period learning of absolute pitch
18 individuals were given Sodium Valproate (VPA) for a fortnight during which they trained on a pitch-training game. Results suggest that VPA…
P i
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