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. B

    Medical Does the human eye have a refresh rate ?

    Does the human eye have a "refresh rate"? This question probably seems ridiculous, but I have no background in physiology and I cannot find anything discussing it online or in my roommate's physiology textbook. I was wondering if anyone here knows whether the eye and brain processes...
  2. L

    What air pressure can the human body survive?

    How much air pressure could a human survive in?
  3. Ivan Seeking

    This is not a 2012 prophesies discussion - Institute for Human Continuity.

    Discussion of 2012 prophesies has been closed, as per the general posting guidelines. https://www.physicsforums.com/showthread.php?p=2269439#post2269439 This is about a commercial that I just saw on tv for the "Institute for Human Continuity", which claims to be "preparing us for the world...
  4. Loren Booda

    Can a human survive on a diet without fat?

    Remove all of the fat you would normally ingest - would you be able to live for long?
  5. H

    Design a Human Touch Sensor Device | Get Help Now

    hi there I'm up to design a device which switches on when human body touches it. I have a rough idea to use IR, Electrical phenomenas of body. But don't know how to start and where to start. help pleasez
  6. GRB 080319B

    What type of surface were human feet originally adapted to

    What type of surface were human feet originally adapted to navigate (plain/savannah, desert, ect.) and have there been any significant physiological changes to the foot throughout human evolution or between humans inhabiting different environments? Thank you.
  7. K

    Biology Careers & Benefits with a BSc Human Biology Degree

    Hi. Do you guys have an idea of what kind of careers are open with a BScHuman Biology degree! And, according to you, which may be more beneficial, a fourth year doing an undergraduate Master (research based) or a 4th year spent on industrial experience? Thank You Kushal
  8. F

    RF testing: Balistics Gel for human analog?

    I am designing an antenna for a consumer product. The consumer will be very close to the device. I have designed antennas for products like this many times before and have the proper equipment to do so. It's low power, meets all FCC regs for our band etc... I am tired of doing the...
  9. R

    Medical The smallest increment of time a human can percieve?

    I tested myself with 120fps in Flash, and I could detect a single changed frame (and the next frame is the same as all the other before the change), so that means I can perceive a 120th of a second. Flash doesn't actually go any higher, but I'm wondering at what point I wouldn't be able to see...
  10. M

    Why does electrical current passing through the human body hurt?

    What's the electrical current messing up that's causing pain?
  11. R

    What is the Maximum Amount of Chemical Energy Stored in a Human Body?

    I only have a basic knowledge biology, but I've wondered about this before. From a "fully charged" adult male human to dying of lack of nourishment; in case of chemical energy from food, this is often said to be three weeks. If it takes that long for a human to lose energy, how much is...
  12. P

    Human observer & cosmological interpretations

    Hi! This is my first time on here and my first post. I don't do professional work in this field but it has been a keen interest of mine over the years. Anyway, if someone can share some insights, I would really appreciate it greatly! Given the divide between classical physics and quantum...
  13. L

    What size of human population can earth sustain?

    A friend of mine said that currently, the "wealthy" 1.5 billion people on Earth consume as much as the poor other 4.5 billion. He also said there are not enough resources (corruption, etc, aside) to have the others live the "rich" life style. Which begs the question... how much human life can...
  14. P

    Human Population: Fact or Fiction?

    i've always been told that the human pop has been going steadily up and up (6E9 in 1999 i think). a site like this http://www.populationaction.org/ seems to support this. now someone has told me this is all a lie by the elite to kill off large segments of the world. ok that's fine - i have no...
  15. T

    What if the swine flu turns out to be the worst pandemic in human history?

    Based on what I have read about the swine flu, it could easily mutate into something extremely deadly, or into something less harmful. The Spanish flu of 1918 killed about 100,000,000 people globally. It had the same name (H1N1) as the recent swine flu (H1N1). I am terrified that within the next...
  16. Mentallic

    Medical Can We Break Human Physical Limits?

    I was reading on the net about 800m distance running to try and improve myself in the event, and then happened to come across this ~ Yes I know this is common sense and again backed up by medical science's experiments on lactic acid build-up and also since the professionals are far from...
  17. B

    How are animals digested in the human body?

    When humans eat steak , the human body converts those animal protiens into human protein. how does the body actually does that ? does it break down the animal protein into its subsequent amino acids or just repair its 3D structure to match that of the human protein structure without breaking...
  18. djeitnstine

    Project Natal: Milo - E3 Stage Demo, Virtual Human

    This probably belongs in the General discussion area but I'd really like to discuss the computer science aspect of this. The AI in this program seems quite amazing. I'm not sure what type of learning this AI has, would it be adaptive or preemptive... This seems like the pinnacle of modern day...
  19. P

    Exploring Gamma Waves and Their Impact on Human Cells

    hi my friends I want some informations to study about gamma wave and interactions of it on humans cells.thancks alot.
  20. M

    Projectile Motion and Human Cannonball

    Homework Statement Hi, I am doing an end of the year calculus presentation on projectile motion in human cannonballs. As an introduction to the projectile motion equations, my group found this problem: The original problem with a figure of it can be found...
  21. K

    Is there Gravity inside the human body?

    Is there Gravity inside the human body?
  22. H

    Medical I'm looking for some general information on human acoustic perception

    Hello everyone, I'm trying to put together a computer program that will convert codes into sounds that can be quickly and accurately picked up by the human ear. For instance, it needs to take "0048" and turn that into a sound, that will be different from "0049" or "1148", and a person...
  23. rootX

    Human rights and the police (misconduct)

    http://news.bbc.co.uk/2/hi/americas/8049633.stm Don't human rights have something better to criticize.
  24. D

    Human Genome Project: Discoveries Beyond Textbooks

    Human Genome Project... Do any of you know anything about the Human Genome Project that wasn't in the standard textbooks? My class has been doing things about genetics research, and the video we watched did not explain very much about it. All it basically said was that the Project was a...
  25. T

    Is Our Free Will Governed by Quantum Physics or Predetermined Destiny?

    I have had a question in my mind for the last while that frankly I don't have the education to even try to answer. (read why not to join the military before university). Considering our understanding of physics, do we have freedom of choice or are all things that happen following a kind of...
  26. M

    Did Humans Live on Pangea?

    Did Human Exist During Pangea? I was wondering how is it possible that man lived in almost all continents of the globe about 5000 - 10000 years back, when continents had there current positions as seen by ancient sailors like Christopher Columbus, The American continents had its own native...
  27. Loren Booda

    The most genetically diverse human

    Would it be possible to tell who the most genetically diverse human is? What significance for adaptation would there be with a person of such genome? Would that person likely have been born in the United States?
  28. T

    Medical Could a supervirus cause the total extinction of the human species?

    I was wondering if the worst case scenario in case of an avian flu pandemic, if it were possible for the virus to cause the total and utter extinction of the human species? What if it mutated into an ultra-pathogenic human strain? There is almost seven billion human beings on planet earth...
  29. S

    Human fetus development inside an egg

    Just a food for thought. Firstly - can a fertilized human ovum develop into any stage of embryo inside of a bird egg (chicken egg, or ostrich egg or whichever...). That conceptual difference between how ingeniously and conveniently birds come to life and how unpractical and actually...
  30. Y

    How Does the Human Eye Detect the Dimmest Starlight?

    hi there. there's an example in the book, but I'm having a little trouble here. Homework Statement Assume that the human eye can pick up as few as 9 photons/s in the visible range. Based on this, estimate the intensity of the dimmest star that can be detected by a night-adapted eye. What...
  31. A

    Can the Human Body Create EM Fields to Affect Electronics?

    To star this post off, I would like to say that I am in not an expert in any field of physics but I do have an interest. So, my question is... Can the human body produce an EM field that is strong enough to affect electronic devices? Examples. computers- I'm pretty competent with them...
  32. B

    Fortran Fortran issue. HEEEEELP? Not a human error, somethings buggy ?

    Fortran issue. HEEEEELP? Not a human error, somethings buggy...? I have no clue why this is acting like this, I'm getting a strange error. I don't believe this is a human error, I've followed the examples perfectly. The picture shows it all. I ran it once trying to use a random function and...
  33. A

    Exploring Human Body Wave Lengths: What Does It Mean?

    Hi We have talked in school about waves and I heard that our bodies have a wave length. What does it mean? I know it's very little. I do not mean our brain but our entire body. Any good explanation would be appreciated.
  34. E

    Medical Searching for the Human Connection -Physics and Music.

    Searching for the "Human Connection"--Physics and Music. Hello everyone! I'm currently a senior in high school (going off to study architecture at either Rensselaer Polytech Ins., Marywood U, or Philadelphia U) and am doing an independent research project on the topic of relating acoustic...
  35. F

    Medical Risks & Shortage of Human Rabies Vaccine for University Job

    Does anyone know the risks etc associated with the human rabies shot? Also, why is there a world wide shortage? I have to be vaccinated against rabies for work at the large animal surgery at my university and I can't seem to get a hold of the vaccine. I keep being told there is a world wide...
  36. Z

    This first thing that Kills a human in Space?

    Sorry I can't find any information on this.. Never mind the how, but if one were to suddenly find themselves floating naked in the vacuum of space what would be the thing that will kill them first? Would it be: * Plummeting Temperature * Lack of oxygen * Pressure (or lack of it) *...
  37. T

    Why Does My Body Act as a Radio Receiver?

    Why does my body act as a radio Receiver.Last year i accidently grabed the socket to my computer speakers while they were turned on at the power outlet.The computer speakers were not connected to the computer and we do not have a radio receiver at all in our home.I only held the plug for one...
  38. M

    Biology Exploring the Genetics Behind Human Diversity

    I am in AP Biology and we have been given an assignment relating to human genetics. The statement is: "Humans are genetically different; yet genetically similar at the same time." Explain why this statement is true. I have been researching day and night for the past 2 days and although I have...
  39. wirefree

    Human voice: Wavelength to frequency

    With reference to the formula: distance (wavelength) = k / frequency what does a wavelenght of 1176470.58 signify with regards to the fundamental frequency of a typical adult female being between 165 to 255 Hz, where d = 300/.000255 = 1176470.58 Would greatly appreciate advise...
  40. S

    What Generates Human Radiation?

    I know we have to expel energy from our bodies in various ways to maintain homeostasis, but what is producing/generating the radiation to begin with? For example, is it the break down of ATP in cells? I've also heard the heart produces an electromagnetic field, and on that note, how is it that...
  41. Fra

    Medical How Well Is the Human Interferon Pathway Understood in the Immune System?

    How well is the human interferon pathways and exact function in the immune system known, and how well is the and regulatory system from gene to protein level known? If anyone has any pointers to reviews of the interferons in the contact of immune system and in particular what regulates it...
  42. F

    Number of chromosomes in each step of mitosis in human

    Homework Statement I basically need to find out the chromosome number present during each step of human somatic cell division Homework Equations N/A The Attempt at a Solution Here's what I came up with: interphase g1 - 23 interphase s - 46 interphase g2 - 23 prophase - 23...
  43. M

    Air pressure caused by wind on human being

    Hi Folks- Is there a way to determine the air pressure caused by wind at a given mph on a human being? Thanks! MD
  44. F

    What is the Average Pushing Force a Human Can Exert?

    Homework Statement Does anyone know the average pushing force a human being can exert? Homework Equations The Attempt at a Solution I did some research online but didn't find anything.
  45. F

    Pushing capacity of a human being

    Homework Statement What is the average pushing force a human can exert? Homework Equations The Attempt at a Solution I did some research online but didn't come up with anything.
  46. P

    Genes that Cause Human Aging: Telomeres, Klotho & Methuselah

    What genes cause aging, most people think shortening of telomeres is the main reason of aging, but I know there are more than that, like Klotho, Methuselah. But which fews are more important than others, and what else are there?
  47. A

    Artificially Controlling Human Emotion

    In the future, if mankind engineered a device that could voluntarily be used to control and manipulate our emotions for the better, should we use them?
  48. P

    Are Human Nature and Human Instincts Distinct Concepts?

    What is human nature and what is known by human instincts? What's the difference between the two? Is there any distinct line differentiating the two?
  49. K

    General Relativity and the Human Body

    In SPH 4U1, (Ontario Grade 12 Physics) we learn the attempts to stop the affects that the human body experiences when in prolonged periods of time in space; such as muscle decay, loss of bone density, etc. So we learn of the attempts to use centripetal force and angular motion to cause a 9.8...
  50. Loren Booda

    What Causes the Range of Eye Colors in Humans?

    What biological reasoning explains the panoply of eye color in humans?
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