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Humans are not the fastest animals. This is immediately obvious from our anatomy. We have heavy calf muscles way down our legs. The calves must swing back and forth at every leg stroke, and require a lot of force to allow any increase of the frequency of the steps. Considering that our muscles have few “fast trigger” fibers, a frequency of about 5 steps per second (300 steps per minute) is really an upper limit for the capacity of our leg muscles to contract and extend.Cheetahs, ostriches, horses, but even dogs and cats, have all the leg muscles bundled way up their legs and connected to their lower points of action by long tendons. This way, free of muscles, the lower part of their legs is very light and can swing at a much higher frequency. Their short muscles, in fact, being closer to the point of rotation (the hip) don’t have to move so much as our long leg muscles, and the force needed to swing a largely muscle-free, very light leg is a lot less than the force needed to swing the heavy, muscular human leg.We also have a rather short foot. The foot is an extra leverage that allows to use the power of the calf muscles (when we walk, as opposed to running, the calf muscles are used very little). The foot acts like a gear: the shorter, the lighter the gear, the greater the force but the lower the speed. The human foot allows the calf muscle to exert a lot of force on the toes, but not much speed. A longer foot will provide less force but greater speed, like a taller gear.If you look at runner animals (cheetahs, ostriches, horses, dogs and cats etc.) they all walk on their toes and their feet are very long, sometimes as long as the other leg bones. We humans are like a motor-vehicle with the gearbox stuck in second gear, while runner animals benefit from a tall gear for fast running.So, if we can swing our legs at a frequency of about 5 steps per second, and each step can be 2.5 m long, this means that the top speed of a human cannot exceed 12.5 m per second which is equal to 45 km/h or 28 MPH, no matter how strong our legs are. These numbers may apply to Usain Bolt, for a normal human the maximum speed would be more like 30 km/h or 18 MPH. That’s fast but not as much as fast-running animals. A fit human cannot outrun a bear, let alone a horse or a large dog. But… we can outrun all of them on the long distance.It is often believed that humans are weak and fragile animals that managed to get through the hardship of the fight for survival by virtue of their large brains. This is not the whole story. It is not much appreciated that humans, given certain conditions, can outrun ANY land-going animal on the long distance. Yes, I wrote ANY and I include ostriches, horses and even camels.How is that? For three extrordinary evolutionary traits of humans: we have evolved the most efficient engine water cooling system in the animal world, we are the only animal with a two-gear shifter and we are among the very few land animals to have rear wheels, sorry, hind legs, drive. Let’s see how.Water coolingMuscles, like all engines produce heat. This is because the chemical energy they receive from the blood cannot be entirely converted in mechanical energy, but only a fraction of it. The rest becomes heat. Heat is good for us: we are homeothermal (hot blooded) animals and our body temperature must be comprised within a very narrow range to allow us to live and thrive. Too much heat, if not adequately dissipated, will raise the body temperature and put our very survival at risk.The muscles of a mammal have an efficiency of about 18 to 26%. This means that 18 to 26% of the energy that comes from the blood is converted in mechanical energy, and the remaining 74 to 82% is either not drawn from the blood or is converted into heat. That’s a lot of heat, if you think of it, and it is very difficult to dissipate adequately.Heat is dissipated through the skin mainly, and the surface of the skin is just so much. Actually, as a body grows bigger, its volume increases with the cubic power of its linear dimensions (length, height), but its outer surface increases only with the square power. If you double the length of an animal, all the rest remaining equal, its body volume will increase eight times, its skin surface four times. So a big animal will soon meet a deficit of body surface through which to dissipate the heat produced by its muscles.The evolutionary solutions to this problems are multiple: elephants have developed large ears with a thick network of blood vessels that act as radiators to dissipate heat; other animals placed a limit to the amount of heat they produce, by reducing muscle metabolism when they need to produce long duration efforts. Others have started sweating.How does sweating help dissipate heat? Water requires a lot of heat to evaporate: almost 2300 Joule (550 calories) per each gram of liquid water that becomes vapour. Water does not have to be taken to its boiling point to evaporate: it can evaporate at any temperature if energy is given to it in different ways, for example by a current of air that flows by its surface.Now imagine having your skin constantly wet and the current of air generated by running makes this layer of water evaporate. Continuous sweating replaces the water that evaporates. Every gram of water that evaporates will remove 2300 Joules of heat from your skin. Your skin blood vessels will transfer heat from the blood to the skin and from there to the water. An athlete can produce as many as 3 litres of sweat per hour, this corresponds to 3000 grams and if they all evaporate they will require nearly seven million Joules of energy. If this is done in one hour, it is equal to nearly two kilowatts of cooling power.So, we humans have a cooling system that can reach nearly two kilowatts of thermal power. It removes much of the heat produced by our muscles and allows us to keep our body temperature stable even under a continuous and intense muscular effort. Assuming a cooling efficiency of 100% (which is never reached) we could, ideally, generate a continuous muscular power of 0.6 to 0.9 horsepower.This is why we have no fur: fur would insulate the layer of sweat that lies on the skin, preventing the air current from making it evaporate. Horses also sweat, but their fur, however short, requires that a much thicker layer of water is formed on their skin than on the bare skin of a human. And heat transmission is far worse across a thick layer of liquid water trapped in the fur, as anyone who has been sweating through a flannel shirt has experienced.Humans have the most efficient water cooling system in the animal world. This feature did not evolve without pain. We had to lose all our body hair, except on top of the head where it was necessary to protect the brain from heating by direct sunlight. We had to develop a complicated and fragile kidney system that allowed us to get rid of a lot of water through a different path. We had to develop a pigment to protect our skin from sunrays, and despite that, we are too often victims of skin cancer. We became dependent on water as sweating is so hard wired in our physiology that we sweat also when water cannot evaporate from our skin. But there is more.2. two gears shifterUnique among all animals (I’d like to be corrected here by a zoologist who knows better) humans can switch from plantigrade deambulation to digitigrade deambulation at will. When we walk we place the entire foot on the ground, and we exploit the leverage offered by the length of the foot only to lift the weight of the leg a short distance. We almost do not use our calf muscles to walk. Why? Because less muscle mass is used, less energy is consumed, less heat is produced. Walking is a slow, but extremely energy efficient way to move. Cats, dogs, horses, camels, ostriches and cheetas, as well as all other running animals, always move on their toe tips, no matter now slow they want to go. They cannot put their calf muscles at rest and their slow walking pace is not as efficient as it could be, were they able to walk on their soles as humans (and bears) do.When we want to run, however, we just shift to a higher gear: we do not put the whole sole of our feet on the ground any more, and we run on our toes (actually, we mostly use the “cushions of the feet” behind the toes, with the toes acting as balancers). This way, the calf muscles can generate a strong force acting on the leverage provided by the length of the foot to lift the entire weight of the body, and we can efficiently use many more muscles when running than when walking.So, we have two gears: a light one for energy efficient, slow walking, and a tall one for strong, fast running or climbing. Also this feature did not develop without losing some previous ability: for example, we lost the rear “hands” which our ancestors probably shared with arboreal apes. Although our species adapted to running, it never became a fast runner, because a long foot, necessary to allow fast running, would have become rather awkward and useless when walking in”first gear”. But there is more.3. hind legs driveOnce again, unique among mammals, we walk solely on our hind legs. We share this ability only with running birds. Most “two legged” mammals are actually four legged that occasionally walk on their hind legs: bears, apes, monkeys and lemurs for example. Australians here will dispute that kangaroos and wallabies also are bipedal. But the fact is that they don’t walk at all. Rather, their evolution led to an even more radical transformation and they became two-legged pogo sticks, where the two legs can only move at the same time, as if they were one. Kangaroos and wallabies are by all means, one-legged deambulators, at least from a functional point of view.Becoming two legged, erect walkers was probably the most painful evolution that humans underwent. The backbone, which was designed to work as a beam, supported by the chest, its tendons and muscles, had to transform itself in a column, with many associated changes and problems. The pelvis had to become narrower, to allow a different position of the hips. This, together with the big cranium of human fetuses, has made giving birth a rather complicated affair. The cardiovascular system had to adapt and transform to account for a difference in static pressure between the head and the feet equal or grether than the systolic pressure generated by the heart, and to allow the blood to flow back from the feet to the heart overcoming a static pressure differential of 80-90 mmHg without blowing the veins of the legs (varicose veins are caused by this pressure difference).But walking and running on two legs instead of four allowed us to use less muscles and less joints, increase our efficiency and save energy (not to mention the advantage of having one’s head and sensory organs above the tallest bushes). One further adaptation towards long-distance mobility.So, our species developed from a primate ancestor which probably resembled a lot more modern apes than it could resemble modern humans. We lost our body fur, we developed a powerful system to keep our skin wet and dissipate heat generated by the muscles, so that we could endure continuous sustained efforts, we developed legs that allowed us to walk efficiently and run reasonably fast, we changed the position of our spine from nearly horizontal to vertical, and we lost a lot of physical abilities in the process.We became the ultra-marathon runners of the animal kingdom. No other animal is able to run for 8 hours at 16 km/h (10 MPH) [What's an Ultramarathon?] in a hot climate. A horse can run much faster than a man, but after one hour, even less in a hot climate, they have to stop and cool off or they will die of a heart stroke. In a cold climate, the problem of body heating is not so relevant: sledge dogs can run for 200 km at sub-zero temperatures, and also horses travel longer and faster in the cold. But humans are unbeatable for their endurance in a hot climate.Arabic camels are often cited as the endurance runners of the animal kingdom, Arabic camels have a wholly different strategy from men to endure efforts, and like horses, they cannot sustain strong efforts for long. Camels are designed to spare water. Because of the environment they have evolved in, they cannot afford to sweat like we do and their body temperature would rapidly increase were they not to reduce their effort. A camel can travel for 8–10 hours, but at the speed of a fast-walking human. Also a human can do that, in fact most people in a caravan of camels crossing a desert walk alongside the camels, but humans can also do better. They can run the same distance in less time than a camel.During the “great Australian camel race”, that was held in 1988, the winner actually walked and ran alongside his camel for 3200 km (2000 miles) from Ayers Rock to Gold Coast. Man and camel had the same long distance performance!WikiVisually.comWhy did we evolve this way? Because for some yet disputed reason we became nomadic. We had to change environment quickly to find food and shelter. The proof of this is that humans exited East Africa where they originated, and adapted to the diverse environments of Asia and Europe very early in the history of this species, while most other primates are still there, clinging to their shrinking eco-systems.All this thanks to sweating, legs that allowed both efficient walking and running and to bipedal deambulation. Incidentally, this last feature left our hands free which provided the opportunity for our brains to grow. After this, we all know how it went.Today we are largely a domesticated species which has lost most of its ability to walk and run. We have almost forgotten that once upon a time, we have been wild animals, roaming the African savannah and beyond, walking so far that no pack of wolves or lions could follow us. We could literally disappear from their hunting grounds and be beyond the horizon overnight. Cool!EDIT #1: thanks to Cole Smith who noted that humans can run as fast as 28MPH. Actually that’s just one human How fast does Usain Bolt run in mph/km per hour? Is he the fastest recorded human ever? 100m record? and 20MPH is a more realistic figure for “normal” humans. I have, however, changed my numbers accordingly.EDIT #2: Thank you for the many upvotes, but particularly for the interesting discussion that is going on in the comments section, which I invite the readers of this answer to scroll.It is time for me to make a confession: I write this kind of anwers mostly for the pleasure of the discussion, rather than for the upvotes. I have no definitive proof that man is really the best long distance runner in the animal world, and my statement in this sense is somewhat provocative. I wanted to be challenged in this (and other statements) and indeed, the challenges came and I collected some very interesting information in the comments.Especially interesting is the real-life account by Pat McCormack and the long comment by Ian Dorward. Also, thanks to Tim Lu who disputed my numbers on the cooling power of sweating and prompted me to do some calculations on an excel sheet of which you can read the results in my answer to his comment.I also want to thank all those who kindly took the time to proof-read my answer, found several grammatical errors and suggested edits. English is not my native language so being corrected in my writing is for me another way to learn something new.EDIT #3: I found out that for some reason, the edits and corrections that many readers are kindly suggesting, are not recognized by Quora and I keep seeing the same typos over and over despite accepting the corrections. So I went through the text correcting them manually and took the chance to make some small changes and additions. Among them a mention of the Great Australian Camel Race that was held in 1988.

•One wonders which of the 5 husbands loved Draupadi the most? Was it Arjuna, who won her hand in the Swayamvar? Was it the noble Yudhisthir? Was it the mighty Bheema, handsome Nakula or the intelligent Sahadeva?•Draupadi and Arjuna is the most talked about pair in Mahabharata. Arjuna wins her hand but she is married to all the 5 brothers (read my other post on this). Arjuna is not happy that he has to share his wife with all the brothers, so he finds peace with Subhadra, Krishna's sister. He favors Subhadra which discomforts Draupadi. She always favors Partha, the archer, the hitman who slays all warriors with a blink of his Gandiva. But alas, Arjuna is busy in his romantic ventures with Suhadra, Ulupi, Chitrangada.In hindsight, Draupadi ignores a man who loved her the most.Bheema.•Of all her husbands, he is the one who loves her the most. He fulfills her every request, he cannot bear to see her hurt.Who brings her flowers from Kuber's garden? -Bheema.Who cries because his beautiful wife will have to serve as a maid to queen Sudeshna? -Bheema.Who kills 100 Kauravas to avenge the insult of Draupadi?-BheemaWho does Draupadi run to when she is molested by Keechak in Matsya kingdom? :Bheema.Who carries Draupadi in his arms because she can't walk in a dense jungle?-Bheema•The other Pandavas are not under Draupadi's thumb. She is prone to outbursts of rage, she makes unreasonable, unwise demands. Arjuna is ignorant on her and concentrates on gaining more power from the gods. Nakula and Sahadeva are nothing but pawns of Yudhisitira, they follow whatever their elder brother says. When she wants Keechak killed for molesting her, Yudhisthir tells her that it would expose their presence in Matsya kingdom, and advises her to "live with it" (Model husband that). Bheema simply walks up to Keechak in the middle of the night and tears him limb from limb. No questions asked.•Draupadi shows us Bhima's human side. He is a savage monster with others, but he is always and only tender when it comes to Draupadi.We all know what happened in the infamous dice game. Dussasana tried to disrobe her but fails (thanks to Krishna). Bheema walks up to the center of the court room and makes a vow"I, pavan putra Bheema, husband of Panchali pledge that unless I drink the blood of Dushashana and break Duryodhana's thigh, I will not show my face to my ancestors"Jayadratha, Duryodhana's brother in law, tried to abduct Draupadi in the forest and she was rescued by Bheema. Bheema almost killed Jayadratha but Draupadi said that he is the husband of Dusshala, Duryodhana's sister and hence your sister too. Don't kill him.•Bheema took a vow that he would slay all the 100 Kauravas. In the 14th day of the battle, he drinks blood from Dushashana's chest, carries the blood and runs to Draupadi. He sprays that blood on her hair and fulfills his pledge. Only after this, Draupadi ties her hair after 15 long years.•Draupadi was the first to fall when Pandavas were on their final journey to heaven. Soon after Draupadi, Arjuna, Bheema, Nakul and Sahadeva followed. It is said that Bheema crawled up to Draupadi and accompanied her while she was breathing her last.Bheema had said -"O my queen, what can I do for you?"Draupadi had replied -"O my beloved husband Pavan Putra Bheema, you are the only one who have given me all that a woman longs for. But I have been ignorant towards you. I have been blind for Partha but you have protected me every single time and repaid me for the humiliation I had received. In our next birth, be the eldest."She weeps and dies in the arms of Bheema.In the horse dance of Tanjore and some other folk dances in South India, the riders of the dummy horses represent Draupadi and Bheema.Edit AnswerWas Draupadi In Love With Karna?Draupadi herself prevented Karna from participating in the Swyamvar, calling him a Suta Putra (This insult by Draupadi was one of the reasons for her downfall in the court room where she was disrobed in public, leading to humiliation of Pandavas, reaping the seeds of war). Karma is a bitch! Many years later, she learned from Krishna that Karna is not a suta putra but the eldest son of Kunti. To this, Draupadi regrets saying.Draupadi Wish....If i had married him..!!! "If I had married him, I would not have been gambled away, publicly humiliated and called a whore. For he has all the qualities possessed by my 5 husbands."Karna who prevented the rape of Draupadi by VasukiKarna had earlier protected Draupadi from Vasuki and then Draupadi had touched his feet sayingHey Angraj Karna, please forgive me for my innocence for unfairly denying you participation in my wedding competition and calling you “Suta Putra”, I take back my words .Today you have protected my modesty. After Shree Krishna, it is you who have protected my modesty and hence, you have risen to a Godly level in my heart. I, panchali, the wife of Pandavas, the daughter of Drupad, the sister of Dhristadhumnya, the mother of 5 brave sons, respect you to equal level of my husbands.”What Karna Said.....!!“Hey Devi, hey Annapurna, hey Kalyani, forgive me too, for I had insulted you in the courtroom. I was blind in the agony of revenge and I didn’t realize your worth. Please forgive me too. I will ensure justice is done to your hairDraupadi Loves become manifold for the Karna...!There are two reasons why he doesn’t kill Bheema, despite having all the options to do so. 1. Karna has given his word to Kunti, that his 5 sons will remain alive. If he kills Bheema, he can’t kill Arjuna. 2. If Karna kills Bheema, he would do injustice to Draupadi’s unstrangled hair. Draupadi has taken a vow that until and unless someone brings the blood of Dussasana’s heart and wets her hair, she will never tie her hair. Bheema has made a vow that he will kill Dussasana and bring his hearts blood to Draupadi. If he kills Bheema in this battle, he will do injustice to DraupadiKarna decides to walk away and not kill Bheema. When Draupadi learns that Karna had spared the life of Bheema, her love and respect for Karna is magnified.My thoughtWhat is truth about Draupadi and karna, we don't know, different-differnt thing mentioned in different books, so Mahabharata is about “Lesson” .“Read it and learn from this”.FootnotesWho Loves Draupadi the Most? An Untold tochy love storyEdit footnotesWas Draupadi In Love With Karna?

History can be changed you never know what happened exactly who edited the history , who are you're ancestors ,!!!.99% humans history is lost and rest are changed , fiction , or rewritten to shape the civilization.. in which different ideology and civilization is clashing eachother..God is not writing the history it's humans who write the history which are tends to courrpt same with all religion books …You never know whom people have that glorious history in india…Hold my Brain Take a example 😉The Germany slowly replaced by Africans people slowly slowly they tends speak German language reading the history of white German they assumed that They are offspring of Germans some how blood also mixed …Suddenly the country see downfall they are not doing anything good In technology , nor in Economy , nor in science , nor in military.. current generation never able to match with previous generation..And then some Started calming that we're one of greatest physicists and invertor why we're poorer today !!History get diluted or annexed by person different origin , or camel is thinking I lived a life of horses..Native aborigines have black skin colour closely related to africa the mixtures happened the outcome become different ..History and religion and all god stuff is only what you get feeded…Take a example of famous personsKamala Harris's mom is from Sri Lanka from a tamilian tribe and people claimed she is from india or from tamilnadu his mom married with Jewish guy from Jamaica and his children will learn the American history of European settlers ..Similarly we're claiming we're off-spring of all people who have rich history and down fall come to every civilization whether it's British empire or Soviet union everyone fall..This is why Better to be focus on future rather than history..Similarly there is no relation between people who live in current Egypt and and ancient Egypt..There current people eagerly want to move out of Egypt .."No poor country gets respect. No matter how wonderful its history, traditions and food are. You want respect for India? Help India get rich. Focus on the economy and condemn anything that harms it. We're doing opposite. upsets business sentiment. Nobody invests in country where people hate each other"