This tag is for questions about the general biological features of human beings (as opposed to the biology of non-humans).

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1answer
22 views

Biosphere that simulates sun and moon shifts

Is there an enclosed biosphere that artificially simulates the movement of the sun and moon at increased intervals? It is known that the sun and moon alter plant movements therefore I was wondering ...
5
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1answer
92 views

Which part of human eyes is getting tired?

It's a thing of common sense that if you read, drive or look at computer screen for too long your eyes will get tired. They burn, itch and try to close all the time. But I was wondering which part(s) ...
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4answers
50k views

What's the maximum and minimum temperature a human can survive?

This is a question that has been in my mind since I was a kid. I'm not a doctor, nor even a biology student, just a curious person. What is the minimum and maximum temperature a human body can stand ...
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1answer
67 views

Simultaneously using both hands - How does that work?

Is some part in one hemisphere the decision maker and "calling the shots" - controlling the opposite side's hand "directly" and controlling its own side's hand through the corpus callosum. Or: is ...
2
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1answer
118 views

Are Asian people shorter than Europeans?

People in different countries have different average heights. For example, Wikipedia's article on human height states that Australian men have an average height of 177.8 cm, and Australian women 163.8 ...
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0answers
60 views

How many blood types are there? [duplicate]

In total how many blood types are there? And why do people normally know only 8 of them? (A+, B+ , AB+ and O+ and Rh- counterparts)
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1answer
52 views

level of organisation of proteins

Is there any disulphide bond in a quaternary structured protein? If yes, please provide examples. In tertiary structured proteins, what is(are) the most important characteristic(s) of tertiary ...
5
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2answers
482 views

The probability of indirect human fertilization?

What is the probability of conception in situations when sperm isn't directly ejaculated into the woman's vagina, like: The man's or the woman's hands come into contact with sperm, for example when ...
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0answers
57 views

What are hot spots on human body?

Recently I have just discovered that a certain amount of the mobile phone frequency can be absorbed by human tissues. For example, this is the SAR info of iPhone 4s: Head: 1.180 W/kg 1 g Body: ...
6
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1answer
263 views

Can HIV be transmitted via breastfeeding?

If a pregnant women is HIV positive and she is treated with medicines to deliver a normal child,can she transfer the HIV virus back to her normal HIV free child by colostrum?
6
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1answer
824 views

What is the normal duration of human sexual intercourse?

Wikipedia is saying: Men's typical ejaculatory latency is approximately 4–8 minutes How the researchers measured this? How did they know if the test subjects weren't suffering from premature ...
38
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1answer
8k views

Why do Humans not produce Vitamin C like other mammals?

Why do most mammals produce their own Vitamin C? Why do Humans not?
3
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1answer
67 views

Can frequent ultrasound diagnostics be harmful?

Are there any short or long term effects apparent in tissues if a zone (or the whole) of human body is scanned with ultrasonic waves often?
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1answer
55 views

Can someone provide resources on human electromagnetic frequencies?

Pardon all of my questions below. I'm basically looking to find online resources regarding my inquiry. If you can answer any of them off the bat, that would be awesome!! It seems that humans and ...
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2answers
288 views

How are proteins formed?

Somewhere, I have read that we need to consume proteins to make amino acids to make new proteins. What does it suggest? How do we make proteins from proteins?
4
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1answer
97 views

What happens to fecal matter if it's continually re-eaten?

After class today, the topic of eating one's one fecal matter came up. There was a sharp divide as to how people thought the defecations would change. I realize this is a bit of an odd question but ...
2
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1answer
70 views

What is the biological function of nose hair?

What is the biological function of nose hair? In general, can we consider underarm hair and pubic hair to be vestigial structures?
5
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1answer
90 views

Why is there no cure for Dandruff?

It looks like a simple problem, affecting almost half of the population at the post-pubertal age and of any gender and ethnicity [wikipedia]. What is so complex about finding a cure? Also, if you know ...
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0answers
34 views

Does healthcare and therapy affect natural selection adversely? [duplicate]

In the last 200 years or so, healthcare and therapy has been revolutionized. Mortality rates are going down everywhere. Even if the disease is terminal, medicine can prolong life for quite a while. ...
2
votes
1answer
110 views

What is the minimum air pressure the human body can tolerate if oxygen supply is not an issue?

Disregarding hypoxia, what is the minimum air pressure that the human body can tolerate? (i.e. at what air pressure would the blood start to boil, or skin start to burst, or whatever else might ...
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1answer
61 views

Religion and Genetics

Are there studies that investigate the heritability of believing in supernatural things (or related concepts)? Or stated differently. Are there studies that ...
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1answer
188 views

What is the effect of garlic on intestinal flora?

Now that we can compare whole microbiomes, has there been investigations on the effect of garlic (or diallyl disulfide, its main ingredient) on intestinal flora? From the proven antimicrobial ...
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1answer
82 views

Drinkable liquids that dont contain water [closed]

Are there any drinkable liquids that don't contain water? By drinkable I mean it would not harm me by just drinking it, like water.
5
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2answers
1k views

Which human cells have the longest and shortest lifespan?

Which cells in a human have the longest lifespan? Which cell has the shortest lifespan?
4
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1answer
194 views

Applying saliva to mosquito bites

Is it true that; when you apply your own saliva to a mosquito bite it would stop itching ?
4
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1answer
399 views

What is in Mosquito bites?

I was wondering what is in the mosquito bites, which causes the swelling of the skin at the bite and also the itching. I know that the mosquito injects some stuff, but what is it?
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1answer
763 views

Why do veins look blue?

I know that veins carry oxygen. Veins look blue because the oxygen-depleted blood in them is blue. Is this true??
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1answer
7k views

Can a person really die quickly from biting their tongue?

A common trope in certain circles (like Eastern martial fiction), is someone committing quick suicide by biting his or her tongue. But is this really possible? The internet turns up millions of ...
9
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1answer
194 views

What would be the conduction speed of A-alpha fibers, were they unmyelinated?

It's known (Hursh 1939) that myelinated axons exhibit the behavior $v = 6d$, where $v$ is the propagation speed [m/s] and $d$ is the axon diameter [μm]. A related relation for unmyelinated axons is ...
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0answers
93 views

Human female chest model or data representation?

I am looking for professionally used representation of female chest (I know how it sounds ;). Generally - a model comprehensive enough to effectively represent human chest, with focus on breasts. ...
2
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1answer
35 views

What is inside IDL (intermediate density lipoproteïn)?

I am studying about the endogene lipidcycle in the human body and I know that VLDL (very low density lipoproteïn) is made in the liver and that it contains triglycerides and cholesterol from your food ...
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3answers
84 views

If the top epidermal layer is burned away, what is it replaced with?

If the squamous (top) layer of epidermis, or skin, is burned or damaged in another way, will it then be replaced by the next layer of below? Also, from where does the basal membrane originate? Does ...
3
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2answers
55 views

Cancer growth and cell division [closed]

I am confused about the prerequisites for cell division and cancer. Which of the following is necessary for the cell cycle to progress? Hormones Growth factor Cyclins Cyclin dependent kinases ...
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1answer
89 views

Why do we suffer abdominal pain after we get very angry or stress?

You also realize probably, when we get so much anger or high levels of stress, after some point we have terrible stomach ache, like really heavy pain. Why is that? How stress or anger can effect our ...
2
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1answer
81 views

What is the evolutionary cause for various finger lengths?

Why are the lengths the way they are with middle finger the longest?
0
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1answer
69 views

What is atrial fibrillation?

I am wondering exactly what a-fib is (causes and symptoms). I would really appreciate having a sample of an EKG with it (because in my limited research, I have found it nearly impossible to find just ...
2
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1answer
44 views

What cells don't have a primary cilium?

It is often stated that most cells in the human body have a primary cilium. Which ones don't? For which cells is it unknown?
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1answer
103 views

Do macrophages engulf mtDNA?

Let us assume that in a human body, a mitochondrial DNA is released to extracellular environment. We know that mtDNA inheritance is solely matrilineal. So the question is, If your mitochondrial DNA ...
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2answers
47 views

Could humans choose to establish fibre digesting colonies in our guts?

Humans don't digest fibre, and nor do any animals, but some creatures have micro-organisms (bacteria, I'm guessing) in their gut which digest fibre for them. My question is, could humans take some ...
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1answer
28 views

Effects of having too much vitamin D?

I saw there was another question about vitamin D; however, I do not believe this is a repeat. What are some of the effects/side effects of having too much vitamin D in your body?
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2answers
2k views

How does HCl does not burn our stomach?

How does the digestive acid (HCl) not burn the surrounding skin of our stomach? It digests majority of raw food we eat but how does it stays safe in our stomach? Also, how does the stomach retains the ...
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0answers
73 views

In-Ear headphones increasing nasal breathing resistance

I figure this is a rather strange question, however, I noticed this quite some time ago and wanted to make sure that this is in fact a permanent condition before posting. The situation is as follows: ...
3
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1answer
38 views

Is there a hormone combination that makes humans grumpy?

Imagine a typical situation that is likely to give rise to a bad temper within an individual: a person is awoken very early in the morning by a sound of a lawn being mowed next door. Unlike expected ...
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0answers
46 views

What is the current scientific position on the issue of human race?

Race is perhaps one of the most controversial and sensitive issues in anthropology, biology, and other related fields. As a non-scientist, I've used google to probe the disparity between the positions ...
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0answers
17 views

Chemical events of fertilization

During the acrosome reaction, the activation enzyme present in the sperm dissolves the corona radiata and zona pellucida enabling the sperm to reach the plasma membrane of the egg. Also calcium and ...
5
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1answer
357 views

Why does it hurt more when you touch a nerve directly?

I am not a biologist nor know much about biology (so please explain in layman's terms) however I have always been curious as to why this is. What causes the difference in pain between touching an ...
4
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2answers
6k views

Why do toenails grow much slower than fingernails?

As the title suggests, I've noticed that my fingernail grow much faster than my toenails. For instance, I usually trim my fingernails every two week or so, but for toenails the number would be about 6 ...
6
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1answer
282 views

Why do people sleep with their eyes open?

It's a fact that some people sleep with their eyes open, but why does that happen? Is it normal behavior, not a symptom of any sort of disorder? Are there any (dis)advantages to sleeping with eyes ...
3
votes
1answer
67 views

Getting goosebumps at will

I can get goosebumps at will, regardless of the environment. Its mostly visible on my arms, and I can feel it on my head. It requires some level of concentration to achieve this. My questions are : ...
0
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1answer
53 views

How does Oedipus complex fit in the evolutionary theory? [closed]

This is somthing that really makes me curious. How is posible that trough a evolution process the best posible candidate is the one that falls in love whith his progenitor?