Human Definition and 895 Threads

Humans (Homo sapiens) are the most abundant and widespread species of primates, characterized by bipedality and large complex brains enabling the development of advanced tools, culture and language. Humans are highly social beings and tend to live in large complex social structures composed of many cooperating and competing groups, from families and kinship networks to political states. Social interactions between humans have established a wide variety of values, social norms, and rituals, which bolster human society. Curiosity and the human desire to understand and influence the environment and to explain and manipulate phenomena have motivated humanity's development of science, philosophy, mythology, religion, and other fields of knowledge.
Humans evolved from other hominins in Africa several million years ago. Although some scientists equate humans with all members of the genus Homo, in common usage it generally refers to Homo sapiens, the only extant member. H. sapiens emerged around 300,000 years ago, evolving from Homo erectus and migrating out of Africa, gradually replacing local populations of archaic humans. Early humans were hunter-gatherers, before settling in the Fertile Crescent and other parts of the Old World. Access to food surpluses led to the formation of permanent human settlements and the domestication of animals. As populations became larger and denser, forms of governance developed within and between communities and a number of civilizations rose and fell. Humans have continued to expand, with over 7.8 billion humans occupying almost all regions of the world in 2021.
Genes and the environment influence human biological variation in visible characteristics, physiology, disease susceptibility, mental abilities, body size and life span. Though humans vary in many traits (such as genetic predispositions and physical features), two humans on average are over 99% similar, with the most genetically diverse populations from Africa. The greatest degree of genetic variation exists between males and females. On average, men have greater body strength and women generally have a higher body fat percentage. Females undergo menopause and become infertile decades before the end of their lives. They also have a longer life span in almost every population around the world. The division into male and female gender roles has varied historically, and challenges to predominant gender norms have recurred in many societies.
Humans are omnivorous, capable of consuming a wide variety of plant and animal material, and have used fire to prepare and cook food since the time of H. erectus. They can survive for up to eight weeks without food, and three or four days without water. Humans are generally diurnal, sleeping on average seven to nine hours per day. Childbirth is dangerous, with a high risk of complications and death. Both the mother and the father provide care for human offspring who are helpless at birth.
Humans have a large and highly developed prefrontal cortex, the region of the brain associated with higher cognition. They are intelligent beings, capable of episodic memory, flexible facial expressions, self-awareness and a theory of mind. The human mind is capable of introspection, private thought, imagination, volition and forming views on existence. This has allowed great technological advancements and complex tool development possible through reason and the transmission of knowledge to future generations. Language, art and trade are defining characteristics of humans. Long-distance trade routes might have led to cultural explosions and resource distribution that gave humans an advantage over other similar species.

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  1. E

    Are there multiple pressures within the human body?

    I recently learned about the pressure of the atmosphere against the human body. It just so happens that this force is in equilibrium with the human body, so we do not feel any pressure. Although if we fly an airplane, we do. This got me to thinking, what of the blood in our veins? Does...
  2. MarkFL

    MHB Koshik the elephant mimics human speech

    I thought this was interesting...the pachyderm puts his trunk in his mouth to modulate the airway, and produces sounds that are recognizable as Korean words: http://www.sciencenews.org/view/generic/id/346259/description/Trunk_in_cheek_elephant_mimics_Korean South Korean Zoo Elephant Uses His...
  3. D

    Can Humans Survive Acceleration from 100 to 7000 mph in Seconds?

    Hi, all. I'm trying to ascertain whether it is remotely possible for a human being to survive acceleration from 100 to 7000 mph (essentially, from 0 to Mach 10) in say 5 seconds? 10 even? Assume the mass that of an ordinary man, and perhaps a co-pilot, the vehicle probably a prototype of modern...
  4. T

    G Forces experienced by human if rotated inside a giant hampster wheel

    I am working on an a project that consists of a giant wheel with a 30m radius that will be rotating at a velocity fast enough to keep a human on the inside surface of the wheel without being attached. Please refer to 30s in for reference of similar motion performed by a hamster: Can somebody...
  5. S

    Human powered wings with jet pack

    Hi guys, i was thinking recently people are trying to fly flapping huge great wings with no success, whilst others are flying with jet packs, so what i was thinking was adding them together. flapping smaller sets of wing assisted by a small jet pack say 2 RC jet engines producing 80-100lbs of...
  6. J

    The heck with the Cat, what about the Human?

    Just wondering about Schroedingers Cat experiment. While in box, Cat is both alive and dead until you open box and measure it according to the Copenhagen interpretation. Thats fine. But if you replace the cat with a human, then the human also is dead and alive until you open the box and...
  7. D

    I'm A Beginner: Relativity & The Human Mind

    I am traveling at 50% C in a rocket ship. My buddy passes me at 51% C in a rocket ship. Assume my buddy is doing long division, & it's required that he writes down his work on paper. Let's go off on a tangent here. Relative to our prehistoric ancestors, the human mind today is far more...
  8. I

    Electric current in the human body

    You mostly hear about electrons as being the vehicle of an electric current because we think of wires and metal. However, if an electric current traveled through the human body, it would be in the form of ions, right? But what happens at the interface between body and wire? I am guessing that...
  9. S

    Resonant frequency of a human body

    Does anyone know why the resonant frequency of a grounded human is smaller when ungrounded?
  10. C

    How strong is human stomach acid?

    This may seem weird, but after a day of acid reflux here goes: Let's say you could shrink yourself down, and get swallowed alive by a healthy woman -- would her stomach be able to dissolve you bones and all? Or would you suffocate before feeling any considerable burning? Would you even feel...
  11. O

    Diffraction limite of the human eye

    Calculate the diffraction limit of the human eye, assuming a wide-open pupil so that your eye acts like a lens with diameter 0.8 centimeter, for visible light of 500-nanometer wavelength. Is there a formula for this? There are two other parts to this question, but if I get this the others...
  12. B

    The physics behind human whistling-where does the sound come from?

    The physics behind human whistling--where does the sound come from? In most whistles, air is split somehow. When humans whistle (by forming a small hole with their lips), this is definitely not the case. I would assume that the mouth is the resonance chamber because pitch can be altered by...
  13. AnTiFreeze3

    Quadruple-Helix DNA Found in Human Cells

    Here is the full article, just published today: http://phys.org/news/2013-01-quadruple-helix-dna-human-cells.html The article makes it apparent that this discovery could be used to inhibit the reproduction of cancer cells. Does anyone know of any other uses that this discovery could lead to?
  14. U

    Desciribing intensity of human scream?

    i was trying to verify the '8 years 7 months 6 days' myth/fact that states that you would have you scream for that much time to produce enough energy to warm up a cup of coffee. i assume that an average human screams at 80 dB.if i have to calculate the power,do i have to take the area of mouth...
  15. L

    Medical What are the physiological processes that initiate human choices and thinking?

    I have a question that maybe basic and psychological in nature but I'm hoping someone with experience in Neuroscience research or any related fields could answer it. As far as I understand it, there is a common debate as to what influences human decisions and what does not which leads to the...
  16. E

    Where Can I Find Research on Humanoid Robot Controllers?

    Is there anyone here who can help me, can suggest or has an idea as to where I can find a latest thesis paper/Journal about a human body mimicking robot that focuses more or had problems on its controller, like EMG, potentiometer, or the likes? I am a fourth year engineering student and I...
  17. jim mcnamara

    Interesting article on early human neurobiology

    Linking brains and brawn: exercise and the evolution of human neurobiology. Raichlen DA, Polk JD. Proc Biol Sci. 2013 Jan 7;280(1750):20122250. Here is the abstract: http://www.ncbi.nlm.nih.gov/pubmed/23173208 A short precis: endurance running provided access to a high protein diet...
  18. K

    Are human beings done evolving?

    Are human beings still evolving or is homo sapien the final stage of evolution? If we're not done evolving, have scientists hypothesized what the next stage of evolution might be like?
  19. T

    Future Human intelligence: Superhuman

    I have watched next world'' Future Superhuman" and they shown what abilities and powers the human being will have in the future. They showned Telepathic communication and what it show is that we will speak to machines and make telepathic calls. Getting smarter was interesting. Digital eye...
  20. Monsterboy

    Reason behind Human Intelligence ?

    Balance ! this is all an ecosystem is about ,balance between predator and prey ,balance between births and deaths but why would evolution lead to a species that can overpower it's own predators and disrupt the entire ecosystem and multiply without any constraints,limited only by resources and...
  21. J

    Human consciousness, awareness or whatever?

    Its a tough question to ask and I am looking for a scientific answer. How can we talk in our mind? I mean when we think about something it feels as if we are talking in our head. They are multiple arguments going on in our head and you can listen to it. What is it? This question arose when...
  22. M

    Transhumanism - human upgrades such as artificial limbs or nanobots

    Transhumanism -- human upgrades such as artificial limbs or nanobots Hi, I'm a physics student (actually doing the third year of my bachelor degree ) in Canada and am wondering what field I should choose for my master and/or phd if I want to work in transhumanism. By transhumanism, I mean...
  23. M

    If you could change yourself into just one other animal (not human),

    if you could change yourself into just one other animal (not human), what would that animal be? I chose a sea turtle. I love them and they are very pretty.
  24. A

    History Wars and battles in human history inevitable?

    Most of the wars and battles that took place happened because of fight for natural resources, right? Could these wars be avoided? Every country wants its survival so they will naturally fight for resources. Now that we have advance technology we can trade resources quickly so fight for...
  25. C

    Problem involving the human body and rate of heat transfer

    Homework Statement If you lie on the ground at night with no cover, you get cold rather quickly. Much of this is due to energy loss by radiation. At night in a dry climate, the temperature of the sky can drop to -40°C. If you are lying on the ground with thin clothing that provides little...
  26. S

    Medical Causes of aging in human beings

    what are the various causes of aging?
  27. S

    Evolving Prime Number Algorithms: Can Computers Duplicate Human Programming?

    there are many prime number algorithm the simplest being dividing all the number less than the prime number. then comes division of number less than or equal half of the number to prime number with the prime number finally the division by all the smaller prime number than the given number...
  28. V

    Medical Low Gravity, Human Health, & the Solution

    Gravity on the Moon is one 6th of that on earth. Gravity on Mars is one 3rd of that on Earth I beleive? Low g enviroments are not good for the human body because they cause bone degeneration and muscle loss. Anyone living in a base on these planets could be weighted down with something heavy...
  29. C

    News What's the difference between many human rights violation accusations and

    What's the difference between many human rights violation accusations and baseless conspiracy theories? For example, I often encounter human rights violations accusations against the Russian government - that it supposed abused the legal system and the state TV system to discredit and jail...
  30. C

    The cause of evolution of human brain?

    Hello, I was interested in human consciousness, and I picked up Daniel Dennett's book "Consciousness Explained" and something he claims there got me thinking: He says that human brain evolved from chimp-size to homo-sapiens-size in a period after humans learned to stand on 2 feet, and before...
  31. I

    What was in between the human chromosome fusion and the 24 chromosome ancestor?

    Human chromosome #2 is the result of the fusion of two ancestral chromosomes. I know humans now have one less chromosome pair when compared to an ancestral population from a while ago, that the fusion didn't happen at once from certain parents to sons. So what steps happened to arrive from 24...
  32. C

    The line between insane conspiracy theories and credible human rights violatio

    What is the formal definition of the line between insane conspiracy theories and credible human rights violations? What usually distinguishes the two, and makes some rational, and others not? For example, 9/11 conspiracy theories don't seem to be credible nor believable at all. However, US...
  33. M

    The Physics Behind a Bullet Hitting The Human Body

    Ok so I'm trying to show how a bullet in real life will not actually make a person fly backwards like it does in movies. I have some idea of how to go about this but need help. So far... I know it's a perfectly inelastic collision since the bullet sticks into the person so would I have to use...
  34. P

    How Much Power Should an LED Emit to Be Visible from 5 Meters?

    Homework Statement In ideal conditions human eye can feel something if 100 photons with wavelengh of 5500A fall directly tu human eye in one seconds time.LED(lambda=5500A) is placed 5m away from human eye. Homework Equations Calculate the power of LED to achieve that the human eye can...
  35. M

    Why is human heart not a centrifuge pump

    Homework Statement Why is human heart not a centrifuge pump but positive displacement pump ? Homework Equations The Attempt at a Solution Maybe bcoz there is no continuous flow of blood. blood goes thru body in packets hence we hear heart beats..
  36. B

    Enlarged Right Atrium: Effects of Severe Coughing for 30 Years

    if you have a severe hard cough for 30 Years can it make the Right Atrium of the Human Heart become enlarged?
  37. B

    Exploring the Pons: A Key Part of the Human Brain

    If you look at the Human Brain and you see the Brain Steam can you see the Pons on\f the Brain Steam or is this part very close to the bottum of the Brain? I ask because some Models show it and other do not but in real life can you see the Pons of the Brain Steam?
  38. J

    Can the human eye detect just a single photon?

    First off, is a photon just one wave cycle of an EM sine wave (2∏). If so, could the human eye detect just a single photon by itself?
  39. A

    Power consumption of a human running

    Homework Statement If a 70kg man is running 3 m/s horizontally, how many watts is he consuming? Homework Equations W = N-m/s N = mass*acceleration The Attempt at a Solution I would assume that in order to get the force in N one would use the gravitational constant of the Earth, but...
  40. F

    Human 'Antenna' with Regenerative Receiver

    I have constructed a small one-transistor regenerative receiver, and I have been getting weird results with reception. I have noticed that simply touching parts of the radio, such as the antenna or around where the antenna is attached, will provide great reception. However, when I am not...
  41. I_am_learning

    The Evidence Behind Human Evolution: Probability & Chance

    We know the exact age of Universe and the earth. We know when life began on earth. Is the formation of life a result of random grouping of atoms and molecules? Is evolution the outcome of random mutations? If so, is the chances of such series of random mutations resulting in formation of...
  42. Darth Frodo

    Is Human Life Inherently Valuable?

    I have been thinking about this recently, and I can't decide. On the one hand, many people bring happiness to other people and in some respect I assign value to that. But if you believe that human life has no value, then this is pointless as the people you bring joy to are worthless as well...
  43. T

    Does a human being ever evolve during his lifetime?

    Maybe not on the macroscopic level, but what about on the molecular level? Is his DNA gets mutated by radiation from computer monitors, does that mean he has "evolved"?
  44. I_am_learning

    How Can the Weight of a Human Head be Measured?

    Just in the middle of random discussion with my friend, we wondered how could the weight of a human head (the portion above neck) be measured? Of-course without doing nasty things. (eg. chopping. :devil: )
  45. H

    Human head gives off smoke when electrocuted?

    I heard that when any human being is executed by electrocution (for instance on an electric chair) afterwards, smoke comes out of his head (seriously). Why does this happen? I think it's got to do with the fact that the human head has a huge number of neurons and their is a lot of electrical...
  46. G

    Human Vaporization: Temperature to Vaporize Human Body

    At what temperature would a human body vaporize?
  47. C

    Resolution of points by human eye

    I'm trying to teach myself optics from Frances Sears' book Optics from 1949. I'm attempting every problem, and there are answers to the odd ones in the back. I've gotten a lot of wrong answers and don't know why, had a few I just couldn't even see how to start, and at this point, I'm seeing...
  48. T

    Fundamental flaws in human mathematics?

    Hi guys I'm wondering about something, currently in our mathematics our number system goes something like this, 1,2,3,4,5... etc all the way to 9, then the whole cycle is repeated when it reaches 10. I believe this method of counting seems to stem from the fact that we have 10 fingers and our...
  49. J

    G-Forces in Space and the Human Body

    Having an infuriating time trying to explain physics to co works. The debate is as follows: to get to Pluto in a quick time, say less than a year, you would have to travel extremely fast. If it were possible to reach such a speed via rockets/ion drive the human body would be crushed under the...
  50. B

    Maximum impulse a human can withstand?

    Homework Statement For a project I am doing I have to disprove something I see in a video. In the video, a person falls into a cart full of hay from a height that is irrelevant. What I know is that the person's speed at the top of the leaves is given by v (I have the actual number for v but...
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