What is Human: Definition and 893 Discussions

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. Nathan M

    Understanding frequency calculations of an object (e.g human body)

    Apologies for the noob question. The frequency of the human body can be calculated based on weins law as follows: Wavelength = 0.002898/310 = 0.00000934838 m Plugging this into the equation λν = c we get frequency = 299792458 / 0.00000934838 = 32069 Ghz Elsewhere, I see that the resonant...
  2. Tony Hau

    B Can the human body affect a radio receiver?

    So I discover that a human body can affect a radio receiver. When I get close to a receiver, the radio produces buzz sound, which means that the radio signal is disturbed. However when I touch the plastic case of the receiver, the receive becomes normal. This phenomenon does not happen every...
  3. Yashi234

    Max lifting capacity for an average human adult

    I have situation where i have drawn a concept with 1 sheet covering width of box for model. But now i need to draw up the manufacturing drawings and it needs to lifted and assembled by 2 people. So i need to know if person weighs 70 kg how much weight they can lift without using mechanical aid...
  4. J

    The Impact of EMR on Human Health: Exploring the Effects

    I've been thinking and researching recently about the effect on human health by electromagnetic radiation created by communication devices such as wifi, cell phones, cell phone transmission towers and high voltage power lines What do you guys think about the energy of electromagnetic radiation...
  5. ZapperZ

    Medical Using Far-UVC Light To Kill Airborne Human Coronaviruses

    I know that there are at least a couple of threads related to COVID-19 scattered over PF, but I want to get a specific feedback on this latest research in terms of human health and safety. This paper was published in Nature, and it presented a rather fascinating result if it is true. The...
  6. Spinnor

    Misc. Use household items to approximate human lung capacity

    I would like suggestions for using household items to approximate human lung capacity. Thinking my lung capacity was at issue (quick research showed it to be about 4.8 liters) I thought how I might measure it using household items and I came up with the following. The opening of a thin plastic...
  7. S

    Human Body Systems Music Video

    I am a high school science teacher working on arts integration for thirty years in schools where many students have academic skills below grade level. I am looking for feedback.
  8. E

    Can Humans Achieve Flight Through Theory Crafting?

    Hi, smart people This quarantine has got me thinking: Can we get people in the air? I have 3 questions that may or may not help answer this question. But I do appreciate any insight. 1. How would one accelerate (the average human) 100 feet in the air and sustain their position? Under normal...
  9. S

    Is the Timing of Heart Sounds Caused by the Opening and Closing of Valves?

    Greetings I am a high school science teacher and music teacher. I am finishing a unit for high school biology and 5th grade science about the human body systems. I have a question about the heart. It involves timing. I heard that the sound of the heart comes from the closing of the valves...
  10. P

    Is the Coronavirus Primarily a Human Virus?

    I keep wondering why we do not know more about the virus? How hard is it to expose some mice to Coronavirus and see what happens? Then I considered that perhaps the virus is primarily a human virus and does not effect other life forms like lab mice. There have been cases with dogs and the...
  11. F

    Action Potential in human cells

    Hello, I understand that the action potential represents a potential difference variation (depolarization) of the voltage across a cell membrane. This concept is generally presented in the context of nerve cells (neurons) as the change in potential across the axon membrane. What about the...
  12. Dr. Courtney

    The Human Body as a Dark Matter Detector

    https://www.sciencedirect.com/science/article/pii/S0370269320301040#br0210 I need to give this more thought, but the ballistics section is pretty good, and I think their basic dE/dx argument is sound: If a collision at a ballistic rate transfers about the same kinetic energy to the human body...
  13. Piotrovskiy Yury

    Is 2000 Kilocalories the Average Human Need per Day?

    Human power 97 watts? 2000 kilocalories is the average human need per day. 2000 kilocalories is 8373.6 kilojoules divided by 86,400 seconds in days = 97 watts.
  14. F

    What Happens When You Dive Too Deep?

    Hello, Human breath the following way: air at ambient pressure is pushed into the lungs during the inhaling phase because the air pressure inside the lungs is lower than ambient pressure: ##p_{inside}<p_{outside}##. During the exhaling phase, the air pressure inside the lungs becomes instead...
  15. BillTre

    Plans for Human Germline Modification being Discussed

    Science news article: Denis Rebrikov of the Pirogov Russian National Research Medical University in Moscow has been discussing how he wants to modify the human germline to correct a genetically inherited hearing loss condition. He has been discussing this for a while, plans on seeking rigorous...
  16. N

    Can the face of others can be transplanted into another person?

    Last night I watched a very intriguing sci-fi movie about human farm where children were raised to serve as reservoir of human organs. in the movie it's the face that is removed from adolescents and transferred to elderly rich clients. I can't reveal the title or it would be a spoiler. I want...
  17. S

    Would VR cause human extinction?

    If we have full dive VR would there still be people living in real life apart from poeple who maintain the VR equipment ? I am referring to VR brain implants/BCIs not VR headsets, googles, etc? I am asking hypothetically since i know that full dive VR is still a while away If you were to give a...
  18. D

    What happens if I apply a voltage to human flesh?

    if i apply a voltage to human flesh, human flesh would be at the full voltage? because i performed an experiment. i connect one end of a wire to the the palm of my hand. i connect the other end to a battery. i connect the first battery to a second battery. i connect the second battery to a...
  19. jaumzaum

    How many alleles per gene the human species have today?

    Hello. Yesterday I was making some calculations, and I started to wonder the average number of alleles per gene the human specie have today. The best question would be how many mutations per base or how many alleles in an average 1000 base gene, as genes vary in size. What made me wonder this...
  20. BillTre

    Dog Brains have been Modified by Recent human Selection

    A new study (original article behind paywall, in short Science mag news article) has shown differences in dog brain anatomy. Different brain regions have been shown to be relatively larger or smaller, in different breeds. The behavioral differences that breeds were bred for correlated with the...
  21. Graeme M

    B The Human Eye as a Detector in Double-Slit Experiment

    Trying to wrap my head around what the double-slit experiment is illustrating, it occurred to me that one could replace a mechanical detector with the human eye. I found that this was tested with what seems an elaborate test setup in 2016, and the result suggests that while an interference...
  22. T

    Are additives and preservatives in food bad for the human body?

    Hi I would like to know the facts about this
  23. F

    I Human eye and its focal length range....

    Hello, The human eye has an average diameter of ##2.5 cm## and an optical power between ##60D## and ##64D##. An object can be brought as close as the near point which is about ##25 cm##. If ##d_{o}=0.25m## (object distance) and ##d_{i}= 0.025m## (distance to the retina), the optical power...
  24. mfb

    CRISPR against cancer in human trial

    crispr-as-gene-editing-human-trials-get-underway?utm_source=twitter.com&utm_medium=social&utm_campaign=npr&utm_term=nprnews&utm_content=20190416]First U.S. Patients Treated With CRISPR As Human Gene-Editing Trials Get Underway[/url] The study takes immune cells out of the patient, modifies them...
  25. S

    Is human vision performed concurrently or step-by-step

    Is most of human vision processing performed in a linear step-by-step fashion in the brain or is it concurrent? Let's take for example; for the process of us recognising a pen on a table. Light/information enters the eye, is focused on the fovea part of the retina because we are focusing on...
  26. chasrob

    The World of Aliens: Seeing Beyond Human Vision

    In a story I’m working on, the antagonists are (humanoid--almost identical to humans) aliens, with 2 eyes, binocular vision. Their tech and bio-engineering is several hundred years advanced from ours. They can see the (human) visual spectrum, but also into the infrared (how far I haven’t...
  27. Auto-Didact

    I Human eyes can detect single photons?

    I'm not sure where this thread belongs; it is essentially a topic at the intersection between quantum optics, human physiology and even psychology, but I will focus more or less on the implications for quantum physics, so I just opted for this subforum. There is a recent article over Scientific...
  28. A

    The effect of macroscopic quantum phenomena on human evolution

    In a discussion between Sam Harris and Brian Greene, at this point, Brian stated that even if we return the brain and all the environment to its previous state, we "WON'T MAKE THE SAME NOISES"; I know that for example, indeterminacy in determining the precise time of decay of an atom (and the...
  29. P

    Hydrogen bonding in human skin

    if the human skin consists of hydrogen, then why does not happen hydrogen bond through contact with something or with another person?
  30. barryj

    How is DNA arranged in a human cell?

    I have read many sources on DNA and still have a few questions. Let me start with this one, and depending on the answers I will ask more. Question 1. f I were to look into a human cell how would I see the DNA? Is there a single very long copy of the DNA string or are there two copies. Question...
  31. Ygggdrasil

    Medical First genetically edited human babies reportedly born

    https://apnews.com/4997bb7aa36c45449b488e19ac83e86d As detailed in the AP news story, most scientists believe the work to be unethical as the safety of the CRISPR gene editing technique used has not yet been fully established. See also...
  32. maxd23

    Compression of human bone: forces

    Homework Statement While unrealistic, we will examine the forces on a leg when one falls from a height by approximating the leg as a uniform cylinder of bone with a diameter of 2.3 cm and ignoring any shear forces. Human bone can be compressed with approximately 1.7 × 10^8 N/m2 before...
  33. X

    The Mystery of Human Luminosity: A Comparison to Daily Energy Intake

    Homework Statement If we assume that a human radiates like a black body, calculate the luminosity in watts, then compare it to the daily energy a human gets from eating. (The area of a human A=1.3 m2) The Attempt at a Solution The temperature of a human is 310K so L=AσT4 =...
  34. NTL2009

    42% of Sea Level rise due to human water use?

    I was surprised to see this in a 'pop science' article a few years ago ("Ask Marilyn"), but quickly found the source, which appeared reputable (to me). But I have not seen any follow up. I finally got back to it. https://www.nature.com/articles/ngeo1476 To stay within forum guidelines, please...
  35. José Ricardo

    (Biophysiscs) Failures of the human body

    https://translate.google.com.br/translate?sl=pt&tl=en&js=y&prev=_t&hl=pt-BR&ie=UTF-8&u=https%3A%2F%2Fmisteriosdomundo.org%2Fessas-sao-as-7-falhas-que-o-corpo-humano-possui-em-sua-estrutura%2F&edit-text=&act=url What do you guys think about this article? Is there some error? Or the article is...
  36. José Ricardo

    The time when AI can overcome humans

    How much time the machine can overcome the human? I was thinking about around 50 years? But I am not sure. I would like that you guys can take me this doubt.
  37. curiousman

    Electrical current through the Human Body

    Hi lads, I couldn't find this info on Google... Are the Heart and Brain the only organs which physiological functions are based on electrical impulses? What happens if we apply electrical current through other organs? Thanks
  38. S

    Insect Endocrinology: How Similar are Insect and Human Nerve Cells?

    It's easy to find descriptions of how the nervous systems of species differ in the organization of nerves, but are there any important differences in the individual cells? For example, are the individual nerve cells of insects similar to individual nerve cells of humans?
  39. R

    If light speed (not in a vacuum) was about human walking speed ....

    If light speed (not in a vacuum) was about human walking speed ... Did any sci fi writer try that?
  40. jim mcnamara

    "bushy" human evolution - commentary in Cell

    https://www.cell.com/trends/ecology-evolution/fulltext/S0169-5347(18)30117-4The authors do not seem to use the term bushy to describe the non-linear evolution of Homo sapiens, but other authors have used it. They use 'African multiregionalism' instead. And also they exclude panmyxia (free for...
  41. José Ricardo

    B Human Eyes vs Cameras: Exploring the Limits of Perception

    When the camera can oversee the human eyes?
  42. T

    Is the human body a heat engine?

    If this is a valid enough definition of a heat engine: All heat engines transfer heat energy from higher to lower temperatures, and do work in the process. ... then is the human body a heat engine?
  43. jedishrfu

    The Far Reaching Effects of AI - Mimicking the Human Voice

    This Bloomberg article profiles the Lyrebird startup where AI can mimic your voice or any voice given a snippet of spoken words. and an earlier Verge article on the technology https://www.theverge.com/2017/4/24/15406882/ai-voice-synthesis-copy-human-speech-lyrebird
  44. DrChinese

    I Big Bell Test Collaboration: Challenging Local Realism with Human Choices

    Not sure if this reference has been posted yet, but I just saw it come through and thought I'd share. This is the "Big Bell Test Collaboration" using measurement choices provided by persons (as opposed to computer generated "random" choices). (The authors are a virtual who's who in the world...
  45. F

    Medical Heating of the Human Body and Radiation Wavelengths

    Hello Everyone, Sunlight is composed of UV, visible and infrared (IR) over a wavelength range from ~290nm to ~2500nm. When we are exposed to sunlight and feel hot, is it because of the absorption of energy at the visible wavelengths and FIR, i.e . infrared wavelength much larger than 2500nm? I...
  46. BMR

    Mechanical Advantage vs. Lever vs. Human Error

    This is my first post here, so pardon if forum guidelines/criteria require this to be designated elsewhere. I am designing a clamp mechanism utilizing lever mechanics, and I am getting conflicting info regarding Mechanical Advantage and the Law of 1st Class Levers. Regarding MA, knowing that...
  47. C

    Postdoctoral Work Stress and the Human Cost

    A friend shared this article with me recently and I thought I might post it here for discussion. The Human Cost of the Pressures of Postdoctoral Research While I'm not sure that academic journals are the right venue for such statements, I agree that as a community it's important for us to have...
  48. T

    New Organ Discovered: Something New Every Day

    Something new every day. https://www.nature.com/articles/s41598-018-23062-6
  49. David Prince

    B Does Human Population Growth Impact Lunar Orbit?

    The next questions will be in english and spanish, since my birth language is spanish I may be mistaken in a few english words. --------------------------------------------------------------------------------------------------------------------------------------------- Spanish Debo advertir que...
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