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. L

    What is the minimum pressure the human body can handle?

    ...assuming very slow adaptation is possible. How low can one go? And something else: if you're at very low pressure, water or blood would boil at RT (pressure is lower than the vapor pressure of water). Would this mean a relatively innocent cut wound would make you lose a lot of blood? The...
  2. S

    How to build a human powered generator

    Hi all, Sorry if this is an incorrect part of the forum. Living a relatively sedentary lifestyle, consuming a Western diet, living in an area where drivers see pedestrians/cyclists as moving targets to run over and after packing on a few pounds, it got me thinking. I'd like to (as a...
  3. A

    Can you be a good engineer and at the same time abe a human?

    I wana become good at math and physics, and become a mechanical engineer. I will like to make contributions to society. But can you be good at this withouth loosing a balanced social life, having a girlfirend and friends and make some exercise xD.
  4. J

    When Did Male and Female Humans Fully Distinguish in Evolution?

    I'm finding it hard to describe what I mean, but here it goes. According to the evolution theory monkeys, apes among others, and humans have a common ancestor - their hereditary line of ascent leads to a common forefather(s). As evolution predicts, let's say, male nipples is a proof that human...
  5. K

    Equilibrium in the Human Body using Torque

    In the movie Terminator, Arnold Schwarzenegger lifts someone up by the neck and, with both arms fully extended and horizontal, holds the person off the ground. If the person being held weighs 650 N, is 60 cm from the shoulder joint, and Arnold has an anatomy analogous to that in the figure...
  6. C

    How Many People Can Earth Sustain?

    Recently watched a documentry(BBC Horizon - How Many People Can Live on Planet Earth 2009) and its scary, could be worse than Global warming.. There are almost 7 billion people in the world today and numbers are increasing rapidly. Soon there'll be 8-9 billion people and we'll all feel the...
  7. M

    Medical Human brain capability in seizure

    it comes together as it goes on ask any questions you'd like So the last couple weeks iv been kinda in a little engineering stage thinking about different ways to produce power and what not in this transition from school to life iv came up with a lot of good ideas and I mean it lol I...
  8. E

    Human Bone Youngs Modulus and Load Question

    Homework Statement A human bone has a youngs modulus of 10^10 N m^-2. It fractures when the compressive strain exceeds 1%. What is the maximum load that can be sustained by a bone of cross sectional area 3cm^2? Homework Equations? F= Y*(change in length/ original length)* cross...
  9. M

    Please help. (is this safe for human consumption?)

    I need to know if this stuff http://www.coleparmer.com/catalog/product_view.asp?sku=8809762&pfx is safe for human consumption. Camphoric acid is supposed to stop sweating in wasting conditions. I had a sympathectomy and can't go outside in the summer without looking like I climbed out of...
  10. Z

    What pressures can a human survive in?

    I know that Earth has a surface pressure of 101.325 kilopascals. So right now we are all under this pressure, but what types of pressures will we start to die at? high and low pressures in pascals please. Thanks.
  11. M

    Future of human spaceflight (again)

    Hi, I'm really not sure what NASA's requirements and such are, but have you ever considered that NASA may very well end all manned space programs in the near future? There are a lot of people who want to see NASA's budget all into robotic exploration.
  12. F

    MATLAB Human Voice Spectrum using Matlab

    Hi, I'm trying to compare the spectrum of male and female voices using Matlab. I'm using this code but I get this error: --------------------------------- Warning: SPECTRUM is obsolete and will be removed in future versions. Use the spectrum objects instead, type "help SPECTRUM". > In spectrum...
  13. E

    The Amount of Human CO2 emissions vs. The Scale of our Atmosphere

    My biology teacher asserted to our class that compared to the vastness of the atmosphere of our earth, the amount of harmful gasses we are emitting is a fraction of a percent and therefore can be dismissed as harmless, and instead we should be worrying about more fragile ecosystems down here on...
  14. R

    How much pressure does it take to pierce human skin?

    I was wondering if any values for this were ever recorded. How strong is human skin when subjected to pressure? Since there are figures for steel which constitutes classical armor and values for bullet proof vests, I wanted to work out what magnitude of protection those things give you against...
  15. A

    Future Human Evolution: Will We Survive to Evolve?

    Do you think that the human species will survive long enough to produce a new subspecies or a separate species? Personally, I think we are doomed to kill ourselves off prior to an new development. However, our species comes from a long line of individuals that have adapted and survived many...
  16. S

    Equations for Human Body Movement: Can Anyone Help?

    please can anyone help me to figure out the equations of human body movement ( walk ) I am in need so badly .. Best Wishes
  17. D

    When and why did human body censorship begin?

    From the breasts to the genitals, when did humans want to start covering themselves (not for protection), and what made them ashamed of their body? No bible jokes please.
  18. C

    Medical Water content of the human body

    I was wondering how the total amount of water in a typical human varies by weight and sex. I saw a site claiming that the typical male/female water percentages by mass were 62% for men and 51% for women; fair enough, though I've seen higher figures. (I'm more concerned with the ratio between...
  19. X

    Physics of the Human Voice: Understanding the Science Behind Speaking

    the human voice...?? Homework Statement The problem asks to explain the physics involved when humans are speaking. and by speaking i mean a normal loudness, casual talking to friends kind of speaking. Homework Equations Not sure if there are relaly any equations to this one...but maybe...
  20. B

    Will we cease to be human if we can no longer breed with isolated tribes?

    I was reading about a tribe in Africa and how they have not changed there ways for thousands of years. There are a few of these tribes left in the world. All these tribes can only have 3 outcomes. They breed with us, they go extinct, or they remain the way they are. If the third prevails...
  21. G

    Exploring the Possibility of Human Souls

    Just curious on your opinions. Do you think humans actually have souls, separate from their mind and body, or is it just part of a chemical process within our minds? I personally believe that people have souls, but it's kinda confusing, because they can seem to be altered by drugs and...
  22. T

    Human cloning was yet scientifically possible

    http://en.rian.ru/russia/20100329/158353194.html I didn't even realize that human cloning was yet scientifically possible. I know that some scientists cloned a sheep many years ago. But other than that, I didn't know people could be plausibly cloned yet.
  23. Orion1

    Unknown Human Group Bone Found in Siberia: New Species?

    Reference: http://www.stltoday.com/stltoday/news/stories.nsf/sciencemedicine/story/0A6FFAE533258165862576F100115AB1?OpenDocument" http://www.time.com/time/health/article/0,8599,1974903,00.html"
  24. J

    Kinetic Energy and the Power of Human Climbing

    How to calculate the height of a person climbs from the third stair up? i don'[y know how to calculate it. HELP! I have the mass=68kg, individual step height=0.16m, number of steps in flight=12 additional question: calculate the average power each person exerted while climbed the stairs...
  25. J

    Are Human Beings Ready for Unification?

    By unification I mean a unified theory of everything. And I am implying that this hypothetical unification would bring forth a whole new level of technology, and assuming that it's application could range from tools of war and destruction, generally speaking god like power. But would also...
  26. R

    If the human mind can think it, it can be done.

    From Wikipedia talk page on time travel: Do you believe this statement? "If the human mind can think it, it can be done"
  27. H

    Does the Heisenberg Uncertainty Principle make human teleportation impossible?

    Scientists have reportedly been able to transport atoms and molecules as much as 1800 feet. Could the same be done for humans, or would the Heisenberg Uncertainty Principle ultimately make it impossible?
  28. F

    Is it safe to use electricity on the human body for muscle reflex studies?

    Hello, I want to build a circuit that can put about 350 microA in my body(to study muscle reflexes etc.). Until now I've come to the conclusion that I need DC in order to get a definite direction of the current. Can anyone help me in figuring out what kind of AC/DC transformer and what output...
  29. D

    Exploring Standing Wave Velocity: Human Error or Physics?

    I just completed a lab in which we created standing waves in a fixed length of pipe using a function generator. An oscilloscope was used to measure the amplitude of the waves. The frequency was changed until a resonant condition was met, and then the location of all the nodes/antinodes was...
  30. D

    Circular Motion and human blood

    For this problem, I tried using the equation: ac=V2/r and put in 2000= ((2*pi*r)/(1/58))2*r What is the distance of a sample of blood from the rotation axis of a centrifuge rotating at a frequency f = 3480 rpm, if it has an acceleration of 2000g?
  31. M

    Human Sex Ratios: 50/50 Chance of Offspring?

    If there is a 50/50 percent chance that offspring could be either a male or a female (at least that's what my bio teacher tells me) then what are the chances that the male/female human population is (for the most part) split 50/50?
  32. R

    Human Eye Optics: Near-Sightedness, Tree Image Distance & Height

    Homework Statement The far point of a nearsighted person is 6.0 m from her eyes, and she wears contacts that enable her to see distant objects clearly. A tree is 18.0 m away and 2.0 m high. (a) when she looks through the contacts at the tree, what is its image distance? (b) How high is the...
  33. A

    What is the mechanism that keeps evolution in human beings alive?

    With advances in medicinesin 1800s and now the avg life expectancy being higher than reproductive age what could be driving human evolution? something like : Hundreds of Human Genes Still Evolving http://www.livescience.com/health/060308_human_evolve.html I understand genes could change...
  34. edpell

    Are Culture or Genes Driving High Family Sizes in Certain Groups?

    Is it culture or genes or both that drive some groups to have high completed family sizes?
  35. Spinnor

    Human in deep space in spacesuit, do they need a heater?

    Say I have a space suit that is heated only by the heat generated by my body and I am located in deep space where the only heat is from the microwave background. If I kept putting more and more of the best insulation around me will I stay warm? Is there a theoretical limit to how much I can...
  36. J

    Understanding Human Color Perception

    Does this make sense?This is the sensitivity of the 3 human cone cells. http://img192.imageshack.us/img192/4562/28030351.jpg This is the range of different colors that the human eye can see. http://img696.imageshack.us/img696/9397/31986914.jpg This color would appear white...
  37. S

    Is Being Born Human a Coincidence or Something More?

    This is my first post, so sorry if this is in the wrong section. I just came across an article which stated "At any time, it is estimated that there are some 10 quintillion (10,000,000,000,000,000,000) individual insects alive." Now, this got me thinking about the number of humans on...
  38. T

    Are human beings done evolving?

    Is the homo-sapien the final stage of human evolution? I've heard of a hypothetical "homo-superior," but I'm not sure if that is actual science or pseudoscience.
  39. B

    Cooling the human body with fans.

    Hi, I'm a cyclist who has just got some rollers, which allow me to ride inside without going anywhere - essential if I want to ride on harsh winter days. The problem is, without the cooling airflow normally experienced when out on the road, heat exhaustion makes long periods of indoor training...
  40. K

    Human Leukocyte Antigen (HLA) typing

    Hi all, I am a little bit confused about the concept behind Human Leukocyte Antigen (HLA). Part of my project right now requires me to do HLA typing from the blood samples with flow cytometry. Here are my questions. 1. The difference between between HLA class I & II compare to MHC Class I &...
  41. R

    Weightlessness discoveries in the history of the human race

    What are the major weightlessness discoveries in the history of the human race and how will they be of benifit to our future?
  42. T

    Could a full-scale thermonuclear war cause the extinction of the human species?

    If a full scale thermonuclear war were to occur, would it cause the literal extinction of the human species, as well as life on Earth as a whole? I've read about military supercomputer simulations of this scenario, and does not result in human extinction. Although many Billion people do die...
  43. Loren Booda

    Exploring Human Offspring: Beyond Viruses and Babies

    What biota with the autonomous potential for reproduction does the human body create besides viruses and babies?
  44. J

    Can Chimps Evolve into Humans?

    Chimpanzees share 98.4% of our DNA, does that mean that Chimps can eventually evolve into a human form of biological life. Questions does this 1.6% difference mean that chimps lack the DNA sequences to eventually evolve or are the existence of the DNA sequences just not present and they don’t...
  45. Monique

    Which Country Tops the 2019 Human Development Report Ranking by UNDP?

    The UNDP has made a new ranking: http://hdr.undp.org/en/statistics/ Norway is still the best country to live in. Top ten: Norway Australia Iceland Canada Ireland Netherlands Sweden France Switzerland Japan
  46. J

    Are there any good viruses for human beings?

    As we all know, some bacteria are good and beneficial to human beings. How about viruses? Is there any good viruses that can be used for human beings?
  47. Spinnor

    Human population verses time, fourier transform of that function .

    Human population verses time, Fourier transform of that "function". Let the human population of the Earth be plotted verses time. Assume that this function is almost continuous. What would a Fourier Time Transform of that function look like? Is there a "strong" exponential component of...
  48. V

    National Human Genome Research Institute

    Evolution :biggrin: Perhaps we can turn this into an educational thread for future reference? I'll start off and add more. From the National Human Genome Research Institute. Watch Darwin at 200: How Geneticists View Him Today by listening and watching this video from The National...
  49. S

    Human Carbon Dioxide Emissions Reverse 2000 Years of Arctic Cooling

    http://www.ucar.edu/news/releases/2009/arctic2k.jsp The associated albedo flip will amplify the warming.
  50. C

    What do human beings do when they communicate?

    Strangely enough, given that this is something we all do all the time, the nature of human communication seems not to be at all well understood. Here’s my take on this – Other animals “communicate” in a certain sense – that is, they make noises or other signals that affect each other’s...
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