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.
The power per unit area radiated by an ideal blackbody radiator is P/A = σT4, where P = power, A = surface area, the Stefan-Boltzmann constant is σ = 5.67 ×10−8 W m−2 K−4, and T = temperature (in the absolute kelvin scale).
How much power is radiated by the human body? Calculate the total...
Does anyone know what is the maximum pressure in which a human body
can function? And how does air pressure affect the minimum breathing frequency?
I suppose increased pressure would allow a person to hold breath longer. For example:
a scuba diver or a person in a diving bell 50m bellow...
well is it greed? emotion? freewill (If you believe in freewill)? unpredictability?
what distinguishes us from animal or machines who share some of the properties above?
Hi I was wondering, if there were any human glycosylases,
other than these, I got this list from DNA repair and mutagenesis, Friedberg EC, Walker GC, Siede W, Wood RD, Schultz RA, Ellenberger T (2006) ASM Press, Washington, DC.
UNG
SMUG1
MBD4
TDG
OGG1
MYH
NTHL1
MPG
NEIL1
NEIL2...
Hello. Let me start by asking your forgiveness for my lack of grammatical skill. I know I need work in this subject. None-the-less, I'd like to ask a couple question concerning my dream. Please keep in mind that college is quite a ways off. I'd like to be prepared now though.
Along with my...
Homework Statement
A human eyeball has roughly a diameter of 15mm. The diameter of the pupil can be up to roughly 5mm. Do you think that the fact that the light receptors on the retina are spaced by at least 2 micrometers is just a coincidence? Justify your answer.
The Attempt at a Solution...
Extinguishing the Human Species
Evidently human females are born with all of their eggs already in their body. I have often speculated that some form of radiation might some day make every human female egg sterile.
“HOW MANY EGGS DOES A WOMAN ACTUALLY HAVE?
A human female typically has...
I want to know how our genes limits and define our growth, I mean, how the osteoblastos knows that they must stop or continue, how our cells knows when to stop growing or dividing, etc.
Every human has a unique "morphology", the bones and skull has their own and particulary morphology, but...
When i learned Newtonian mechanics i had this question is that we know a object have certain inertial.. but why does it acts this way? what actually is inertial?
we know f=ma but why it works that way?
we know so much about quantum mechanics but why is it true?
In today's world it seems...
Hello,
Would it be possible to clone a whole new human body and then transfer your existing brain to the clones body. Would that be like having a fresh new body? Would you be able to live forever if you repeated the process? I'm sure that there would be many complications. However if they...
I understand that topo-physiologically, the human body is a donut. i.e. not only are we a donut physically, but we are a donut as an organism.
Our skin is an interface between the outside world and the inside of our bodies. Bacteria and other microbes have to get through our skin defense...
Homework Statement
A 50lg man jumps off a bridge 80m high. He lands in choppy salt water feet first. Each foot has an area of 75cm^2. The goal is to find out
a) What is the force sustained by the human body while hitting then decelerating in the water.
b) depth of penitration
Because...
France accused in Rwanda genocide
This story is really part of a bigger one, where magistrate Jean-Louis Bruguière accused Paul Kagamé (current president) and his entourage of involvement in the death of the former president, Juvenal Habyarimana, a Hutu.
Maybe the ICC can help ? :devil:
Does a persons attitude, or way of life affect their internal body? I don't mean it as a couch potato will be weak. I mean it as a picky person will they have allergies? Will a germ phobic have ...
Has there ever been an estimate for total human caused heat output?
If all humans and human activity were removed from Earth would the temperature fall?
A week or so ago, my high school physics teacher sent us all summer work - we have to write an article explaining the processes by which electromagnetic fields (particularly low frequency electromagnetic fields) could effect the human body. Since then, I have been wading through the large wealth...
This was accidentally posted in the general forum so I moved it over to a more appropriate section of the forum...
Hey guys:
Just needed to know if this logic/math is accurate. I haven't taken a science class since my undergrad days and it was ages ago so I am not too confident with all the...
http://www.measureofamerica.org/
& WOW is there some appalling stuff about the so-called "world's only superpower," if anyone cares. Here are some tidbits that stood out for the British media...
Please correct me if i am wrong.
As per MWI,when an observer open the box,schrodinger cat will be alive in
one world and the same cat will be dead in other world. If we replace the cat with human,then the dead human and alive human will be different worlds.so,my curious question is does this...
Human tissue contains about 3*10^27 electrons per kg of material. Suppose two humans are located 1370 km apart and each has a mass of 60 kg. We now transfer 5*10^21 electrons from one person to the other. What will be the magnitude of the resulting attraction, rounded to the nearest Newton?
I...
Homework Statement
Under favorable circumstances the human eye can detect 1.0e-18 J of electromagnetic energy. How many 600-nm photons does this represent?
(Modern Physics, Arthur Beiser, 6th Edition, Pg. 89)
Homework Equations
My answer is unreasonably low. My mistake is probably very...
Is human flight possible? I'm not talking about flapping your wings. I'm talking about flying like Superman. I think it's possible. Does anyone have an explanation? I fly all the time in my dreams and I feel like I could fly in real life. Please be serious about this post because I am.
Hello everyone :)
There is an alien that just came to Earth and is having trouble recognizing peoples faces. We also have trouble recognizing his face; where his eye is on one hand and a mouth on the other. Luckily for us the alien understands our language and simple colours.
The task is...
Since the human mind has a relatively large degree of freedom, it can do things on its own will. How does the human mind fall under the laws of entropy?
Unfortunately, magnetic fields are by their nature invisible, but scientists from NASA’s Space Sciences Laboratory have managed to put on film what these natural phenomenons would look like if we could see them with our own eyes. Please note that this is a simulation and has been created using...
[SOLVED] center of mass
in which direction would the center of mass of the body migrate if the arms were raised overhead? what about if the person had a bilateral amputation of his legs?
http://scienceblogs.com/erv/2008/05/hahahahahahahaha_you_guys_omg.php
There is an MP3 on that entry, obviously, and you should NOT listen to it, but you will. Very long intro, over a minute and a half long, so you can skip that. Also, some commercials.
From my limited knowledge of the physics of the human Eye.. I got the impression that the
image enters the brain via optic nerve which I always assumed to be an electrical impulse
circuit. But if this were indeed the case, vision interpretation would be purely a psych/brain
function. The...
The human ear canal is about 2.8 cm long, if it is regarded as a tube that is open at one end and closed at the eardrum, what is the fundamental freq. around which we would expect hearing to be most sensitive? Take the speed of sound to be 340 m/s.
Is it:
wave speed = frequency x wave...
Hi,
Can H. sapiens and P. troglodytes produce (infertile) offspring? Has there ever been any experiments where this has been attempted? Which position is more theoretically sound?
Are we no more than animals, I know we separate our selves from the animals because we can manipulate our environment, shape and mold things out of steal. I think we are a truly violent race; if you would put 30 people in a room with no way out, the people would divide themselves and invertible...
I don't want to ask this question in a New Age metaphysical type of way so please don't interpret it as such. What frequency does the human body run at?
Does this question make sense or is it too broad?
I will try to fire off a frew separate examples of what I mean so that the question...
as a human canon fly zaccini flied a distance of 53 meter in 1940 ( still record )
his velocity as he leave the cannon is 24,5 m/s in a angle a with thw horizontalplane
a) what is the angle ? ( 31,2 )
b) find the highest point during the record ( 8,04m)
can you set up theese tasks ?
I know this hormone can be dangerous and that using it isn't going to extend your life or anything...but can it affect height? Theoretically is there a way it could be used to grow a few inches, if so how much and in what way? (In someone in their 20s as opposed to someone in their teens) If not...
Human spaceflight is an essential part of both the US and Russian space programs. Many of you at this site apparently lament this. I have encountered numerous arguments along the lines of "If only all that money NASA wastes on human spaceflight could be directed to science." Redirecting that...
I heard the virus' natural host is a flea commonly found on cave-dwelling bats, especially the vampire bat. Is this an actual virus, is there any info about it?
Hello,
I need some help figuring out how to proceed.
Homework Statement
Make up a ruler, that can measure human reaction time in time intervals of 0.05s. There supposed to be 6 intervals in total.
We did a similar experiment in class, where a student drops a ruler and I need to catch it as...
Homework Statement
(1) the torso, neck, and head (total mass = 42.3 kg) with a center of mass located on the y-axis at a point 0.423 m above the origin, (2) the upper legs (mass = 19.8 kg) with a center of mass located on the x-axis at a point 0.190 m to the right of the origin, and (3) the...
I recently saw the movie 'Sunshine' where they send a mission to detonate a bomb and save the Sun from dying. In one of the scenes, two astronauts had to cover a distance in the outer space but they didn't have space suits available. They wrapped themselves in some kind of foil and the whole...
Is it possible to have a negative sound intensity level?
A sound that is below the threshold of human hearing has...
(A) a negative intensity level (in dB).
(B) a negative intensity (in W/m^2 ).
(C) an intensity level of zero.
(D)an intensity level less than 1 dB , but greater than 0...
Im curious if anyone knows if it is theoretically possible to place the human mind into an infinite loop in a similar manner to the placing an electronic computer into one.
If not, why? What is principle physical/neurological process that prevents this from occurring?
In the same way every time we look at the stars we see the past of the universe. Can we see our history placing a extremely powerful telescope pointing towards the Earth an arbitrary number of light years away?
I know that would require faster than light travel, but maybe we could shortcut...
I was reading and attempting to understand Max Tegmark's research on the multiverse, and I found this:
http://science.howstuffworks.com/quantum-suicide.htm
Now, while How Stuff Works is generally a good site, there are some areas that they could have been clearer on. The paragraph...
Hi all,
I am very new to this forum so please let me know if I have posted this in the wrong place, and thanks in advance for any replies :)
Backstory:
My friends and I were playing a game called Portal in which you can place two portals (each of which leads to the other). We were...
Could the exclusion of the SIR2 gene lengthen the human lifespan 6 times? it's been shown to lengthen lifespan like that in animals such as worms right?