Questions tagged [human-biology]

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
29 views

What are the genetic basis for further classification of human beings? [closed]

According to anthropology, human race further gets divided in Caucasians, Mongoloids, Aboriginals, Eskimos, Red Indidians and Negro's. How far, is this classification, though maybe anthropologically ...
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3answers
8k views

Why are bald heads so “shiny”?

Why do males with baldness have shiny skin on their head, whereas we don't experience such "shiny skin" in other parts of body without hair.
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4answers
8k views

Are there biological reasons why life expectancy is lower for men in most countries of the world?

I've been checking life expectancy figures for men versus women in many countries of the world and the figures for men sometimes are terrifying. Countries like Russia have a 12 years gap in disfavor ...
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2answers
68 views

Why isn't life expectancy normally distributed?

Lots of phenomenon in nature can be plotted onto some sort of normal distribution, and that makes intuitive sense to me (such as human height). Why then, does global human life expectancy drop off so ...
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0answers
10 views

Nutrition and experimental biology

We know that food in the stomach is present in the form of chyme treated with pepsin and hydrochloric acid, if we take food crush it with saliva and then treat it with Pepsin and HCl (in the lab),and ...
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0answers
6 views

Is atrial natriuretic peptide relased when we drink water?

I know that osmolarity is controlled by the hypothalamus and recover by ADH which reabsorb water. It also can be released when ECV is very low. ECV/salt is controlled by aldosterone/atrial ...
17
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1answer
3k views

Are human bodies programmed to die?

Following from this question: What is the evolutionary advantage of death?: Is there any evidence that human bodies have systemic self-destruction built into their developmental program? I'm not ...
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1answer
42 views

How important is getting enough glucose for maximal brain performance / cognition?

I know from many studies that have been done, that resting versus active use of the brain has relatively similar overall energy expenditure levels. On the other hand, however, we know that the brain ...
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1answer
114 views

Coronary circulation

It is said that the coronary artery that gives the posterior descending artery(PDA) determines if the heart is right dominant(most cases) or left dominant. Is there any reason to this? Why PDA?
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1answer
69 views

What is a deep exhalation/inhalation?

I tried to find the academic definition of deep exhalation/inhalation but found nothing special. I speculate that the correct definition is as follows: • Deep ...
2
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1answer
45 views

How do painkillers prevent shock?

I was reading about the Placebo effect and came across this little story: The roots of the placebo problem can be traced to a lie told by an Army nurse during World War II as Allied forces ...
3
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1answer
93 views

What is a catalytic domain?

I have to answer a few questions from an article I'm reading, and I am just really confused on defining "catalytic domain." I have to relate it to the antibiotic Teixobactin. Is catalytic domain the ...
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2answers
232 views

What was the biological mechanism that allowed Tarrare to eat so much?

Are there any conjectured mechanisms that cause Tarrare's extremely oversized stomach and abdominal cavity? Along with his superhuman appetite of course. Whether from a medical perspective or a ...
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1answer
35 views

Are there any benefits/disadvantages/traits from having a permanent lower core temperature?

My body temperature as far as I remember has always been around 35.6 degrees Celsius, that's a degree less than what is the usually quoted as the average temperature for humans. Are there any known ...
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0answers
31 views

Does intelligence depend more on environment than on genetic factors? [duplicate]

Many have argued that the test of IQ is simply a test of language. The application of the test consists of asking a number of questions. The person should understand the question presented to them and ...
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0answers
29 views

How much Oxygen can the Human body carry?

Basically - the title: How much Oxygen does a human body carry at a single point? What have I tried: A friend of mine has done some calculations and came up with the following numbers. Neither of us ...
4
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1answer
106 views

Does body absorb nutrients less efficiently if we ingest the same amount at the same time, opposed to spreading over a larger period?

I would like to understand if ingesting a certain amount of nutrients will result in different absorption from my body, depending on whether I ingest that amount spread over time or everything at once....
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0answers
23 views

Does any tendon in humans receive a high amount of blood supply? Or is the property of not receiving a large blood supply a constant across tendons?

I read on https://www.physiocomestoyou.co.uk/blog/all-you-need-to-know-about-tendons/ (mirror): [Tendons] do not have a large blood supply. Does any tendon in the human body receive a high amount ...
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0answers
28 views

Apply ficks law to explain biological examples of diffusion [closed]

Apply ficks law to explain biological examples of diffusion. I have researched this question and found the equation for ficks law rate of diffuion= area of diffusion surface x difference in ...
5
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1answer
50 views

Can stress and arousal be independent?

I'm trying to figure out if it's possible to have a stress response without being initially, or simultaneously aroused. I'm defining stress to be physiological stress (ie. release of cortisol) and ...
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0answers
29 views

Is it possible to buy a DNA sample with a specific mutation?

I would like to test a genotyping method (ARMS) on a specific human snp (heterozygous or homozygous ). Unfortunally, we do not have any dna samples with the mutation. Is it possible to buy somewhere a ...
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0answers
51 views

What are areas of the body where stab wounds are not lethal? [on hold]

I do not know if this stack exchange is the most appropriate one for this question, and if not I apologise and hope it will be redirected to the correct stack exchange. As title indicates, I'm ...
4
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1answer
126 views

When does the brain stem appear in humans?

This article states: Once the neural tube closes, at around week 6 or week 7 of pregnancy, it curves and bulges into three sections, commonly known as the forebrain, midbrain and hindbrain. ...
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1answer
19k views

How late in a human pregnancy can a zygote split?

This page indicates that the first two days is "very early" for a zygote to split, and that conjoined twins are the result of an "extremely late" split: If the zygote splits very early (in the ...
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0answers
18 views

How to overcome the tiredness feeling which come after studying 60-90 minutes [closed]

I am preparing for a examination called JEE which have physics, chemistry and maths questions in it. I study in slots of 10 minutes, for the first 9 minutes I study and and than completely rest for 1 ...
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0answers
30 views

How long can a human survive in a vacuum? [duplicate]

I’m curious how long a human could survive in a vacuum, how he/she would die, and if an O2 mask or tight-fitting clothing would help.
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Can we drink water before brushing teeth? [on hold]

It is written almost every where to drink water in the morning empty stomach but should we do it before brushing or after brushing?
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30 views

Could ions inside lungs produce hydroxyl?

I am not proficient in either biology or chemistry. However, I have a question which I can't find answer to. It seems to belong somewhere between chemistry and biology. I apologize for any errors and ...
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1answer
23k views

Why do Asian people have black hair and Northern people have golden hair? [closed]

I have got two questions. Why do majority of Asian people have black hair? Why do majority of people from the northern countries (Sweeden, Norway, Finland) have light (golden) hair? Thanks for an ...
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0answers
30 views

Can we “learn” reflexes?

Can we force our bodies to react to situations faster than our brain can think about them? Some reflexes I can think of off the top of my head: knee jerk reflex retracting hand when touching a hot ...
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1answer
64 views

Does the 1:1 sex ratio at birth apply to every human pregnancy or is it a statistical average?

Are there genetic factors that biase the sex ratio of offsprings for each person but average to 1:1 for the entire human population, or does the 1:1 ratio apply to every single fertile person?
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0answers
27 views

Clone instict of life [closed]

If we create 2 clones of a person, how would they behave to each other? I mean, would they protect each other at all costs or work as separate beings?
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1answer
20k views

What would cause a single white eyelash?

I couldn't find a paper who could give me the explanation. Unfortunately, according to my search, it seems there are not many reported case, particularly for the younger population (<30). Would ...
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1answer
31 views

What do we mean by MHC molecule diversity? Does each human have a variety of MHC molecule isoforms?

I'm going to try and explain what I think I know From what I understand, MHC/HLA molecules present peptides to T cells. To be able to present peptides from a wide variety of pathogens, they need to ...
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2answers
2k views

Can UV radiation be safe for the skin?

It is well known that UV radiation can damage the DNA and generally harm our skin. We also know that UV radiation helps on the production of melanin and Vitamin D. From what I could find, the DNA ...
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0answers
17 views

Adenosine Triphosphate is used as energy supplier why not GTP / CTP / TTP [duplicate]

All are having Triphosphate ATP / GTP / CTP / TTP Why only ATP is used as an energy supplier?
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1answer
140 views

Does estrogen increase muscular growth in females?

Regarding humans it is said that most psychological effects caused in men by testosterone are caused in women by estrogens. There are many studies on that, particularly regarding temporary shifts of ...
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0answers
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Is attractiveness linked to total population of sexes?

I ask due to linking in with some pre University research. I am seeing if there are studies and if you can link them to me about if The rating of attractiveness per female is more if there is less ...
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2answers
1k views

Special visceral efferent

Why are special visceral efferent nerves are named as such? They are supplying motor impulses to muscles of pharyngeal arch, which are both skeletal(facial) and visceral(laryngeal) 1, so why only ...
3
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1answer
70 views

Does eating hard food really cause wisdom teeth to erupt properly?

According to the article Bad molars? The origins of wisdom teeth, in our evolutionary history, people were eating harder food like nuts and had unimpacted wisdom teeth. Later, that article appears to ...
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5answers
12k views

What is the evolutionary reason behind the fragility of teeth?

Almost all organs in the human body have a rather large threshold within which the organ or tissue is capable of repairing itself using materials supplied by the body, whether it's made from organic ...
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3answers
322 views

Serological assays measuring antibody response

Given that an appropriate immune response to a bacteria may be thwarted in an individual, including not producing all of the antibodies which are known to occur in people who have been infected, or ...
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0answers
64 views

What are the sufficient criteria that make an entity a living homo sapiens? [closed]

When I say criteria I mean like x biological functions or y genetics. If it were to be appearance,anatomy. A corpse completely looks like a man. Moreover a person who has had their 4 limbs amputated, ...
4
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2answers
101 views

What could humans do to “see” what dogs smell?

We're able to see a lot of things using computers that we can't see normally: yellow-green, UV light, X-rays, etc. What do we have that harnesses the ability to "see" what dogs smell (e.g., harnessing ...
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1answer
511 views

Does a generator potential pass along a nerve the same way an action potential does?

I have read that a generator potential is a localized depolarization of a membrane. Does that mean that it does not pass along a neuron the same way an action potential does ? If not, then how do ...
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0answers
42 views

Why do I have 95% of chimpanzee's DNA, and only 2% of Neanderthal's DNA? [duplicate]

Excuse me if it is a question with a simply answer, but I don't understand these discoveries, looking a discrepancy from my unknowledge of genetics: I have 95% of Chimapanzee's DNA, and, I have [...
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1answer
2k views

What is the difference between Amino acids from blood and urine?

I would like to understand the difference between different tests for Amino Acids. Any blood laboratory offers amino acids tests using 3-4 methods Blood serum Urine Random Urine 24 hour (all the ...
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0answers
22 views

How does the cardiovascular system improve upon repeated, strenuous exercise?

New here, hopefully this is the right place to post this question. It's widely known that repeated, strenuous aerobic exercise gradually improves the capacity of one's cardiovascular system — $\text{...
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0answers
16 views

Are cold weather tolerance and spicy food tolerance related physiologically?

If a person grew up in a cold place they happily walk outside in winter in short sleeves and shorts in places with mild Winters while the locals are bundled up in thick jackets. Spicy food with ...
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1answer
57 views

Are casein proteins in UHT milk digestable for infants or toddlers?

As a novice cheesemaker, I have read that Ultra High Temperature prosessed milk is unsuitable for cheesemaking, as casein proteins are denatured and cannot be curdled with rennet. I have verified that ...