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.
Does anyone know what is normal voltage for a young, physically healthy human male?
If you take a usual voltmeter and will ground the negative end how many millivolts do you suppose to read by touching dry human skin with the positive end?
Is there suppose to be some difference between skin on...
Hello,
I don't even know if this two are related in the way I think, but this is what i would like to know.
for example
If we traveled far away from the planet Earth and looked back at it (no telescopes), we would see a blue marble but would not be able to see for example our familly...
Hallo all. I've got instruction from moderator to explain and share my findings on the matter. so I'm going to post the thread again.
My question was. Whether Giant human like 30 to 90 ft tall possible or not.
The reason why I've asked this question is that we often see some unrealistic...
Hello everyone,
Ok I read the definitions but I'm confused. What I'm thinking is genome, is the amount of DNA in one diploid cell. So when they say we have 20 000 genes in our body, are they referring amount of DNA in one diploid cell. Also what do they mean when they say human genome is...
I am aware that the human body has electrical properties, But was baffled by what I witnessed Christmas Eve. I had a malfunctioning electric candle in the window. I picked it up to check the tightness of the bulb, and it immediately came on. I set it down and it went off. Three times this...
Gravity is an important force in this world. if we presume humans have evolved over millions of years through a process of evolution why all the major and cellular mechanisms not gravity dependent. From our food intake to processes of excretion, blood pumping, breathing and down to cellular...
What is the probability of humans surviving beyond the Earth given:
- the historical rate of technological advances
- the rate of human expansion Vs available Earth resources
- the ability to locate and survive on another planet(s) that can support human life - taking into account the...
The amazing 'Howard the Human Projectile' is fired straight forward from a 300 kg circus cannon during a recent Ringling Bros. Barnum and Baily performance in La Plata. Howard has a mass of 75 kg and the cannon recoils with a velocity of 2.5 m/s, at what initial velocity does Howard leave the...
Given that we humans are descended from the great ape, as well as are gorillas and chimpanzees and bonobos, why do we have hair that grows indefinitely, while they do not? I've read something about a sexual selection aspect to evolution, surmising that hair is a means to finding a mate, like...
hi there, i came across this video https://www.youtube.com/watch?v=kIbYiO5BRYk http://www.youtube.com/watch?v=kIbYiO5BRYk, and before I buy the set I'd like to know how the human body metabolized gallium metal/ions. I've read quite extensively on gallium metal, but I can't find much info on how...
Is possible for human muscles to contract from resonance at certain levels/ranges of frequency?
I have been a lot about how with the right frequency, one can induce contractions in diff parts of the human body. Does anyone know about this? If this is true, then what is the way you can...
Primo Levi: "Human Surface"
Homework Statement
http://answers.yahoo.com/question/index?qid=20101205082200AAZCums
What calculation did Primo Levi use to get the following conclusion:
According to Primo Levi's book, if the human mass of 250 million metric ton would be spread over the...
about human power??
consider the worker needs to bring up 40kg, the floor is about 36m so the work done is
w = (40kg) (10m/s^2) (36m)
w = 14 400J
i don't know what's the (10m/s^2) for??
I've been reading about parasitic host manipulation and was amused by the section on T. gondii (cat poop parasite) and it's effects on human behavior, especially on women.
Look what the cat dragged in: do parasites contribute to
human cultural diversity?
Kevin D. Lafferty∗
page 280...
We know that color is a sensation in the brain from interpreting different wavelengths of light. Therefore, color does not actually exist in the real external universe. Why not take it a step further and say that the sensation of brightness is a human concept. Not that actual magnitude of...
Greetings,
A curiosity –
I recall from school being shown the derivation (from quantum mechanics and statistical physics) the derivation for the PN silicon junction –
Along the same lines of thinking –
Can it be derived to show the human body’s temperature is 98.7 (or whatever the...
A computer prints two papers,
on the first paper is written, "ASDDSF DFGDF ERSDKUF DFD RRVFDSDA"
on the second paper is written, "HOW ARE YOU HSHJFD SDF JGYJHNF LKJSFL"
One might say the first paper has some random letters which are generated by a computer randomly. But he might say the...
Hello readers, I have been thinking and if you bear with me hopefully I don’t sound too mad!.
I have read an interesting article and in it a leading scientist has claimed that A detailed, functional artificial human brain can be built within the next 10 years. Henry Markram, director of the...
is there a limit to the amount of force a human can generate?
for example in superhero physics it is shown the original superman can leap 660 feet. The author has shown the amount of force required to accomplish this
f=ma, a=v/t, v^2=2gh
Velocity>v^2=2*32*660> 205/sec or 140miles...
I=V/R, so the amperage is determined by the voltage and the resistance of the human body, right?
But yet it is possible to have a high voltage but low amperage current go through you, say you grabbing 2 electrodes which have the a high voltage between them. How come the amperage is low and...
What is "action" in human terms?
A friend, humanist by profession, asked what is "power"? Well, that was easy to explain in human terms. You do a certain amount of work, you use a certain amount of calories, you can do you work slowly, during one day, or you want to do it in one hour. Then you...
Homework Statement
You are being hired by circus owner to design a cannon which will launch a human into the air toward a net 50 meters away (at the same height). THe design should conform to the following specifications (ignoring air resistance):
1. The circus tent has a maximum height of...
[b]1. The human brain consumes about 22 W of power under normal conditions, though more power may be required during exams. How long can one Snickers bar (280 cal per bar) power the normally functioning brain? [Note: The nutritional calorie, 1 cal, is equivalent to 1000 calories (1000 cal) as...
Hi,
I am not biology student and I want to know this
In our body, which organ can live for long time and how long it can live? also which is the organ with shortest life?
Nowadays people talk about donating eyes, kidneys after their death. So I got this doubt, that whether these organs are...
Hi, I have taken an introductory undergraduate QM course, solving for different boundary conditions like particle in a box, but the physical interpretations of some of the tenets was not well explained. I was surprised to find this paragraph on Wikipedia:
"Published by Werner Heisenberg in...
Hypothetically: If a hollow sphere with a human inside were placed exactly at the centre of the Earth's core; then how would gravity affect the human (or any mass for that matter).
My friend who thinks we were "created" keeps telling me that there's no link of a human evolving from a previous species..
Now I keep telling that there's tons of evidence in museums & whatnot, but is there any good links online that can clearly show him?
Hello guys, I've been thinking about a concept, and to some of you, it may seem like slightly different version of reincarnation, but take it as you may because I'm an atheist and I don't believe in afterlife, and this may sound contradictory to what I'm about to say..
Bare in mind that the...
I would like to know the use of lactose and galatose in human with regarding to their solubility.
how does low solubility of lactose can be made good use on human?
what are the uses of galactose for human other than making guma?
I've found very little about the actual definition of human instincts! Besides reproduction, perhaps violence, & one or another item, seems there should be a list! We are known to be a social animal, which, to me, means that gatherings & mob mentality (not only in the negative sense), are our...
Homework Statement
determine the stopping distance for a car with an intitial speed of 26.9 m/s and a human reaction time of 0.9s for an acceleration of -4m/s^2
Homework Equations
x=vt t=v/a x=x+vt+.5at^2
The Attempt at a Solution
I used the second equation to find total...
Homework Statement
The human heart is a powerful and extremely reliable pump. Each day, it takes in and discharges about 7,500 liters or blood. If the work done by the heart is that of an average American female, 1.63m; and if the density of blood is 1.03 x 103 kg/cubic meter,
a) How much...
Homework Statement
If a person breathes 10 liters per minute or air at 68 deg(F) and 50% relative humidity, how much water per day must the internal membranes supply to saturate the air at 98.6 Deg(F) (Assume all moisture is exhaled) If each gram of water extracts 580 calories as it is...
How many of you have ever been excluded from a position because the company made all applicants take the myers-briggs or a compentency skills assesment?
Just wondering, because in my software life I got a lot of consulting work because companies could not hire the talent to do development...
Homework Statement
I was asked by my lab teacher to investigate the effects on the human body of being exposed to very high and very low pressures, and while I have found some good sources of info it is not that easy to find good and quotable sources, I was wondering if anyone could offer some...
I am working on a design for a human operated technological exploration suit. I have the energy supply worked out and designed to scale and tested in small scale prototype. I would like to put together a team from here to help develop this unique system for deep sea exploration. I would also...
This is what you get if you compile numerous attractive females and then take all their features to come up with archetypal faces that is supposed to best represent the group they belong to.
Do you think that eventually all human races will be homogenised? With all the globalisation and people of different races having children together, do you think that eventually there will be no more 'race' - like there will only be one type of human- we would all look indistinguishable from...
If there was an isolated human population that eventually became unable to breed with any humans outside of their population, would they become classified as a different species than us?
While listening on my english lecture, my teacher told us that authors usually have similar word choices and sentences structures on their writings.
Because of that, I began to wonder if it is possible (if it hasn't been done already) to quantify the human language (if that's the right term...
i live in a hilly location where i have very difficult radio reception, so i am always futzing around with my little "active" antenna for FM radio (PBS). i notice that reception always improves as i move near the antenna (like within 3-5 feet is noticeable), and gets much better if i just touch...
Hi,
I am a physics student who just finished his bachelor thesis in nonlinear dynamics. I am about to start the physics master programme at my home university (in Germany). Within a year, I will have to start writing my master thesis, so I'm trying to figure out in which domain I want to work...
Another possibly unusual question from me, may also enter in the realms of philosophy or math, but I do not think that physics is a wrong place for it.
It is possible to find information about size of the universe and number of atoms in it and such. We as humans can imagine numbers of...
Would the human eye be able to pick up a picture from the Hubble Telescope unaided if it were close enough? For instance, how close would I have to be to the Pillars of Creation in order for it to fill my entire field of view if I were floating in outer space? I assume several hundred light...
Homework Statement
The auditory canal of the human ear extends about 2.5 cm from the outside ear to the eardrum
(a)Explain why the human ear is especially sensitive to sounds at frequencies around 3500Hz.
Homework Equations
Speed of sound v=344m/s
The Attempt at a Solution
I know...
When I was 2 years old I contracted pneumococcal menengitis and it destroyed many of the hair cells in my cochlea - resulting in profound deafness. I wear a cochlear implant at the moment but I was wondering:
When will it be possible grow human hairs cells with stem cells, or when will it be...
Hello,
I'm new on this forum and I hope I will blend in nicely. I happen to have a couple of questions on the Alpha Centauri star in the constellation of Centaurus. I know the distance between this star and our milk way is huge, but suppose one could travel at the speed of light X 25, would...