Edward I was 6'2", Edward IV was 6'4" and his younger brother George was 6'0". Given that his cousin Philip V of France was also notably tall, genetics would seem to be a factor as well as good diet and living conditions. And.. it's hard to pin down an accurate "standard" of physical stature for large swaths of history, as quality of life could vary greatly from decade to decade or country to country depending on the climate, weather (droughts and famines), and socio-economic conditions affecting different classes of individuals. Additionally, certain groups, like the Flemish, Celts, and Norse, were considered typically above-average in height, though to what degree nutrition and environmental factors vs. genetics caused this is again hard to say. But back to horses, what they can carry depends a lot on the size, breed, and what they are expected to do. Those little Icelandic horses can carry a helluva lot for their size, but they aren't built for speed. Arabians are notably speedier, but don't do so well with heavy loads. Medieval knights were carried by larger horses than either of these, bred for a mix of strength and speed... so tbh, there isn't a universal load-bearing standard that can apply to all horses any more than a convenient size standard we can compare to all men. As with anything else, it probably makes the most sense for someone experienced with horses to judge what one can carry on a case-by-case basis.
Some interesting (if a bit dry) reading here: http://www.uni-tuebingen.de/uni/wwl/koepke_baten_twomillennia.pdf Basically, there is no single average height. They tracked up and down over the last 2000 years, with the low points being the 12th and 17th centuries. They also mentioned that most of the surviving armor is from the 15th-16th centuries. I've seen before, and its mentioned in this paper, that there is a "gap" in the historical record from the 12th-14th centuries. Most of the artifacts etc. did not survive. According to this report, they even had difficulties finding complete skeletons for the time period (they said the bones were more scattered, I'm assuming that's the time period when they started re-using graves). All that being said, we're still not talking about "average" people, but I don't think anyone has ever done a study on the sizes of the nobility (if they have, it would take longer than a 5 minute Google to find it, and I honestly don't care that much about the subject). And I apologize if I'm a stubborn bastard
As a physics / biomechanics note I'd like to state that the colder it is, the more beneficial it is to be big and vice versa, the smaller you are the better suited you are to hot climate. It is simply a matter of surface area to body mass ratio. The bigger the creature in cold, the less it loses heat and the smaller the creature in hot, the more it can dissipate heat through it's surface. Hence why it makes sense to develop wings and fins if you're living in hot desert.
This seems backward. Most natives to very cold regions tend toward short and round. It is the hot and dry region natives that tend toward tall and slender.
Neither of you have sources.... Although Sheep has a point if you look a animals, like Seals, polar bears, whales, wooly mammoths... all these large creatures that either live above the Arctic circle, or deal with cold temperatures more often than not are generally large. Also, me being the size I am, I find that I can deal with cold temperatures a lot more comfortably than hot ones.
Although, if you look at the Inuit and stuff, I can see your point. It does more depend, I think, on how much the wind is a factor when dealing with cold. Since humans are bipedal, it would makes sense for the shorter spectrum, but since animals like the polar bear are quadrupeds, then they can afford the larger size since they area already closer to the ground.
Humans don't have a huge range in terms of body mass : surface ratio. But, you wouldn't find many elephants roaming a hot desert. Also, there aren't a lot of very small land creatures on the polar caps. Though that alone isn't proof of the concept, you can look at pure physics, energy consumption rates, heat dissipation rates and such. While the larger the creature, the less it dissipates heat is true and vice versa, it is also true that the larger the creature, the less the amount of energy it consumes increases. Elephants don't need to consume tens of tons of food every day, hummingbirds need to consume several times their body weight and need to actually nearly fall to coma while they sleep so they don't starve to death when sleeping. The proof of concept comes from thermodynamics as discussed by Steven Vogel in his great book Cat Paws and Catapults, it is a book on biomechanics and human's technology and it is very insightful. One of the important topics in the book is the scale of creatures. You can't just take a bird and apply a multiplier of 50 to it's three dimensions and expect to have a tremendous aircraft, not even if you turned the bird into metal. Physical realities are very different for small and large creatures and humans are by far from the biggest end of spectrum regarding size of creatures. For any human group, the various closed groups have their own genetic lines. It could be that while being large and round would be a benefit in cold that another factor would be more crucial for an inuit with good clothing - such as lesser energy consumption that comes with smaller size. So, in an environment where food is scarce you would need to balance between the energy needs of being big and between being large and having low heat dissipation. Human creatures can simply put on another layer of clothing and this will be of greater value than weighing 200kg and then walking on treacherous ice. So, although for inuit the size would help with heat issue, he can simply wear more clothes and avoid the difficulties that increased weight bring for people who use a lot of boats and walk on ice. Harp Seals are big, round and full of fat. http://en.wikipedia.org/wiki/Bergmann's_rule "Human populations who live near the poles, including the Inuit, Aleut, and Sami people, are on average heavier than populations from mid-latitudes, consistent with Bergmann's rule.[12] They also tend to have shorter limbs and broader trunks, consistent with Allen's rule." Length is not only factor determining weight. You can be short but sturdy. But still, for humans imho these things are not as straightforward due to humans non-physiological (read, technological) adaptations. You can look up as many examples of Xerocole species as you want, especially desert dwellers. Not a whole lot of large creatures on that list. Many of them have things like long ears on rabbits, wings on birds and such that help with heat dissipation.
