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1500 questions
92
votes
6 answers
How could humans have interbred with Neanderthals if we're a different species?
To be clear, I'm not doubting that Homo sapiens and Homo neanderthalensis did interbreed: of that much I'm convinced.
Within the past few years I've seen an upcropping of pop-sci articles discussing the interbreeding between pre-historic species of…
Dave Kennedy
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Why did the process of sleep evolve in many animals? What is its evolutionary advantage?
The process of sleep seems to be very disadvantageous to an organism as it is extremely vulnerable to predation for several hours at a time. Why is sleep necessary in so many animals? What advantage did it give the individuals that evolved to have…
Gordon Gustafson
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89
votes
6 answers
Are humans the only species who drink milk as adults?
I was drinking a glass of milk the other day and that got me thinking that no other animal to my knowledge drinks milk past their infant stages. One could argue that cats might but it isn't good for them to do.
Are humans the only animal that are…
ggiaquin16
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84
votes
2 answers
What's up with this leaf?
This cool design was "tattooed" on this leaf.
I found it on the windshield of my car.
What's up with it?
Jossie Calderon
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84
votes
2 answers
Why is the heart not in the middle of the body?
All mammals that I can think of have a high degree of bilateral symmetry (In fact, almost every animal I can think of is like this).
So why is the human heart not exactly in the middle of the body? An effect of this is that one lung is slightly…
DrZ214
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84
votes
4 answers
Death because of distilled water consumption
One of my friends said that I would die if I drank distilled water (we were using it in a chemistry experiment) I gave it a go and surprisingly did not die.
I did a bit of Googling and found this
It said that drinking only this kind of water could…
The-Ever-Kid
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83
votes
3 answers
Why 20 amino acids instead of 64?
This question got me thinking about amino acids and the ambiguity in the genetic code. With 4 nucleotides in RNA and 3 per codon, there are 64 codons. However, these 64 codons only code for 20 amino acids (or 22 if you include selenocysteine and…
Daniel Standage
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83
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3 answers
Is there an RGB equivalent for smells?
Millions of colors in the visible spectrum can be generated by mixing red, green and blue - the RGB color system. Is there a basic set of smells that, when mixed, can yield all, or nearly all detectable smells ?
Spartacus9
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77
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2 answers
Do animals exhibit handedness (paw-ness?) preference?
I have been observing my cat and found that when confronted with an unknown item, she will always use her front left paw to touch it.
This has me wondering if animals exhibit handedness like humans do? (and do I have a left handed cat?)
One note of…
Thomas
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76
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3 answers
Why shouldn't dogs eat chocolate?
I was wondering why dogs shouldn't eat chocolate. Can't dogs just excrete the indigestible component in their droppings?
It's common knowledge that dogs shouldn't eat chocolate. What I don't know is why chocolate would kill them, from a specifically…
rockinboy3303
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74
votes
1 answer
Why do Humans not produce Vitamin C like other mammals?
Why do most mammals produce their own Vitamin C?
Why do Humans not?
Gabriel Fair
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73
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3 answers
How does the brain's energy consumption depend on mental activity?
What is the impact of mental activity on the energy consumption of the human brain?
I am most interested in intellectually demanding tasks (e.g., chess matches, solving a puzzle, taking a difficult exam) versus tasks with a similar posture but less…
Piotr Migdal
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73
votes
5 answers
Why are there no wheeled animals?
In physics, "almost everything is already discovered, and all that remains is to fill a few unimportant holes." (See Jolly.) Therefore, on Physics SE, people are veering off into different directions: biology, for example.
Thus, it happens that a…
user3395
71
votes
2 answers
What is the evolutionary advantage of red-green color blindness?
Red-green colorblindness seems to make it harder for a hunter-gatherer to see whether a fruit is ripe and thus worth picking.
Is there a reason why selection hasn't completely removed red-green color blindness? Are there circumstances where this…
Christian
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67
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2 answers
Can a woman give birth to twins with different fathers?
Is it possible for a woman to conceive from two different men and give birth to half-siblings?
Probably
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