Biology pertaining to humans
37
votes
3answers
567 views
Is there a reason why human eyesight and plants make use of the same wavelength of light?
The accepted range for the wavelengths of light that the human eye can detect is roughly between 400nm and 700nm. Is it a co-incidence that these wavelengths are identical to those in the ...
26
votes
1answer
2k views
Why Does Salt Water Help Sore Throats?
I am having some trouble understanding how salt water, a simple solution, could so effectively remove the pains of a sore throat.
I do believe that the answer is closely related to hypo/hyper-tonic ...
24
votes
1answer
4k views
Why do Humans not produce Vitamin C like other mammals?
Why do most mammals produce their own Vitamin C?
Why do Humans not?
24
votes
4answers
589 views
Human perception of time depending on age
From what I can tell and what thus far all people with whom I discussed this subject confirmed is that time appears to "accelerate" as we age.
Digging a little, most explanations I found basically ...
22
votes
3answers
3k views
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 ...
20
votes
3answers
2k views
Is there any advantage to one blood type over another?
All humans can be grouped into ABO and Rh+/- blood groups (at a minimum). Is there any advantage at all to one group or the other? This article hints that there are some pathogens that display a ...
20
votes
3answers
270 views
Is telomere length a reliable measure of health/lifespan?
Several companies are commercializing tests for telomere length such as this one here. I understand the basic mechanism for why telomeres shorten during DNA replication, but how good is the evidence ...
19
votes
2answers
350 views
Why don't teeth glow?
Hydroxyapatite is the main component of tooth enamel. It contains phosphorus in the form of phosphates, pyrophosphates etc. that are found to exhibit the the property of phosphorescence. But why don't ...
19
votes
5answers
439 views
Why do we age? or Do we have a theory of senescence?
There seem to be a number of ideas about why we age. Hypotheses include the gradual accumulation of cell metabolic products affecting organism function and the reduction of telomere length during cell ...
18
votes
2answers
3k views
If a human takes antibiotics are all bacteria in the body killed?
From my basic understanding, antibiotics kill living things, bacteria for example.
Do the antibiotics consumed by a human-being distinguish between what they kill? Or do they just kill every bacteria ...
18
votes
2answers
218 views
Why is rabies incurable?
I'm still not sure about the mechanics that lead to rabies being incurable. I know that it can be treated before any symptoms show up, but why is it that once symptoms show the person is a dead man ...
17
votes
4answers
2k views
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
...
17
votes
2answers
830 views
How long do your eyes need to adapt to darkness and reach full contrast?
I heard you should wait some time until your eyes adapt to darkness and are able to see smallest luminosity differences, otherwise you might overlook faint objects in the ocular. Are there any rules ...
16
votes
2answers
232 views
Why would diffusion be faster across a non-specialised tissue?
The standard protocol for a person experiencing chest pains is to chew a 300mg aspirin tablet, the argument being that chewing rather than swallowing the tablet results in the aspirin entering the ...
16
votes
1answer
373 views
Is kissing a natural human activity?
The word natural here is meant in contrast to it being a sociological construct.
Is kissing in all its forms something natural for humans? Is it instinctively erotic? Or is it just a conventional ...
16
votes
2answers
15k 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 ...
16
votes
2answers
234 views
Can an adult without genetic lactase persistence still develop a tolerance for dairy foods?
While investigating the rise of adult lactose tolerance, I came across the news that China has been encouraging its citizens to drink more milk, even though most of the Asian population lacks the SNP ...
16
votes
1answer
1k views
How does laughing gas (N2O) work?
Laughing gas (N2O), well, makes people laugh.
How does just a gas make us do that, there has to be some hormones at work...
So, I wanted to know how this works? What is the mechanism?
16
votes
2answers
2k views
What causes fingerprints to form and why is the pattern formed unique?
I've found research that suggests that the reason we develop fingerprints is because they aid us with feeling surfaces (Scheibert, et al. 2008) and not to increase friction and help with the gripping ...
15
votes
2answers
1k views
How do the brain and nerves create electrical pulses?
I have heard that information is sent between the brain and peripheral nerves via electrical pulses or signals, but I don't understand how they create them in the first place.
15
votes
2answers
1k views
What is the mechanism behind “acquired” alcohol tolerance?
I can understand natural variation in alcohol dehydrogenase (ADH) in a population leading to variation in rate of inebriation (after controlling for other variables -- e.g., mass, food consumption, ...
14
votes
4answers
1k views
How many genes do we share with our mother?
Somewhere I have read we share more than 99% of our genes with every other other person and 98% of our genes with chimpanzees. What does this mean? Don't we share 50% of our genes with our mother and ...
14
votes
2answers
619 views
How and where, in the human brain, are memories stored?
Background
I am a computer programmer who is fascinated by artificial intelligence and artificial neural networks, and I am becoming more curious about how biological neural networks work.
Context ...
14
votes
3answers
308 views
Are human fetuses more likely to be male?
Question: From a physiological point of view, when sex is determined in a human fetus, is it equally likely to be male or female?
Studies in this area typically measure age at birth, where the data ...
14
votes
1answer
630 views
Why do we get runny noses in the cold?
The most annoying thing for me about being cold is a runny nose. Is there an advantage to having a runny nose when cold? What does having a runny nose achieve?
14
votes
5answers
249 views
Are there any substance that are more dangerous at low dose than at higher dose?
It is commonly admitted that
The dose makes the poison
which means as a person, the more I take a substance, the more risk I take for my health.
There is even an indicator called LD50 (see ...
14
votes
2answers
933 views
What actually happens when my leg 'falls asleep'?
Most people have experienced the temporary loss of feeling and tingling in their leg resulting from sitting in an abnormal position for a short while. Usually you get a loss of feeling in your leg ...
13
votes
8answers
3k views
Why have humans evolved much more quickly than other animals?
Humans have, in a relatively short amount of time, evolved from apes on the African plains to upright brainiacs with nukes, computers, and space travel.
Meanwhile, a lion is still a lion and a ...
13
votes
3answers
1k views
What causes the development of antibiotic-resistant strains of bacteria?
I understand bacteria have become resistant to antibiotics due to selection pressures, but how do resistant bacteria process antibiotics when exposed to it, compared to non-resistant bacteria. Also, ...
13
votes
2answers
241 views
How is temperature sensed?
Can anyone summarize the mechanism by which when an object of a given temperature is placed in contact with, say, the skin on a human fingertip, the average speed of the particles of the object is ...
13
votes
4answers
647 views
Can two humans with 44 chromosomes produce viable offspring?
It is known that there are very few individuals having 44 chromosomes, not the usual 46 chromosomes.
One example is a male in China: the first article, the second article.
The other is a female in ...
13
votes
2answers
404 views
Does testosterone increase female sexual behavior?
According to my lecture notes testosterone generally increases sexual behavior.
Given that it's generally thought to be the male hormone I'm not quite sure whether they mean that it also increases ...
12
votes
2answers
102 views
Relationship between our microbiome and personalized nutrition
Recently, it has been asked whether there are 'metabolic types' between humans that can benefit from a sort of personalized nutrition. One answer suggested that one discerning factor could be the ...
12
votes
2answers
482 views
How does a brain distinguish stimuli?
If all the brain ever "sees" is action potentials, how do we know that one set of action potentials denotes a flash of light, another one signifies a loud sound, etc ?
12
votes
2answers
4k views
Possible? When a pregnant woman suffers an organ damage, fetus would send stem cells to the damage organ to help repair it?
I am quite sure that there is this blood-placental barrier between the mother and the baby so that nothing (except a type of antibody) can pass through it.
But I remember reading somewhere that when ...
12
votes
1answer
3k views
Why do mammalian red blood cells lack a nucleus?
How did the red blood cell in humans get to lose its nucleus (and other organelles)? Does the bone marrow just not put the nucleus in, or is it stripped out at some stage in the construction of the ...
12
votes
1answer
402 views
Does bioluminescence occur in humans too?
I read that Japanese researchers have developed very sensitive camera that recorded bioluminescence in humans; is it possible and if so what is the mechanism behind it?
12
votes
2answers
221 views
Do probiotics survive digestion?
Pretty much this. I've been wondering if any of the yogourt and other "health" foods containing living probiotic cultures survive digestion to populate our intestines? If so, is there peer-reviewed ...
12
votes
1answer
618 views
What causes REM atonia to be lost in sleepwalking?
I understand that in normal REM sleep the voluntary muscles are in effect paralysed in order to prevent an individual acting out their dreams. This paper indicates that there are likley to be ...
11
votes
3answers
556 views
How does the human body metabolize gasoline?
A Chinese man has been drinking gasoline to relieve his pain for 25 years. How does the human body metabolize gasoline? Also, what are the side-affects to gasoline?
11
votes
3answers
408 views
What happens to dextrorotatory amino acids in humans?
As indicated by this question, most of the amino acids in the human body have the L-chirality. As enzymes also have handedness, what happens to the D-amino acids that end up within the human body? Are ...
11
votes
2answers
201 views
Is the 'fluttering feeling' when under stress neurological or physical?
I'm sure that everyone is familiar with the sensation commonly known as "butterflies in the stomach". It is commonly experienced during periods of anxiety or stress (e.g. before high stakes job ...
11
votes
2answers
312 views
Do human beings have pheromone receptors?
What is the current consensus on whether or not humans have receptors that detect pheromones?
If there are purported receptors, in what anatomical areas are they located? With what organ systems do ...
11
votes
4answers
1k views
Do white Australians have a distinct look?
Background
I've heard from many people working in tourism or similar industries that, white Australians can be recognized as Australian solely by their facial features. Being Australian myself I've ...
11
votes
1answer
187 views
Is it correct that the body only responds to the most painful stimulus?
I'm rather ashamed to say that this question is partly based on an episode of House.
I have previously heard that, if there are multiple simultaneous painful stimuli, the mind will only feel the ...
10
votes
2answers
141 views
Why is the microbial ecosystem of the gut so susceptible to disruption by pathogens?
From all accounts, it seems as if the Escherichia, Enterobacter, etc. that live and thrive in the human gut are pretty well entrenched. I know that these microbial populations are often analyzed as ...
10
votes
3answers
255 views
Where does the 'C' in exhaled CO2 mostly come from?
When a human being exhales $CO_2$, what is, by the numbers, the main source of carbon atoms exiting the body in this way? I mean what class of cells, or which tissues are the biggest on a pie chart of ...
10
votes
2answers
258 views
Could an “overactive” brain increase the chances of Alzheimer's Disease?
From Raichle ME. 2010. Two views of brain function. Trends in cognitive sciences 14: 180–90:
Alzheimer’s disease (AD) is the most common cause of progressive
cognitive decline and dementia in ...
10
votes
1answer
295 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 ...
10
votes
1answer
2k views
Why does scar tissue change color?
I was wondering why, when you are cold, scar tissue turns bluish or purple while original skin stays the same color.
The only thing I can think of, is that maybe scar tissue gets less circulation ...
