Grass in Africa. It’s about 4’ tall. Man was about 5’ tall, so when he stood upright, he could see over it. This is why the successful species of man is/was around 5’ tall. Since, then, an increase in diet and medicine has made mankind a bit taller. Note that “hobbit” lived in Jungle, not grassland, and so forth.
Note that I am not contradicting **Blakes **overall excellent post- just refining it.
That’s pretty wild speculation. And remember that Lucy’s kind (A. afarensis) was only a bit taller than H. floresiensis. In fact, the earliest hominids were all well under 5 ft tall, so your hypothesis holds water.
Of course, if you have a cite concerning a human ancestor from the 5-6 Million years ago range that is reported to have been 5 ft tall, let’s see it.
That is, your hypothesis DOESN’T hold water. Sorry for the poor editting.
Homo Erectus was much taller, and it is thought that his height increase co-incided with a change in climate and hunting systems.
http://www.msu.edu/~robin400/erectus.html
Here’s a quote from another cite:“Many scientists believe that sudden deteriorations in the climate caused early man-like creatures to turn to meat and to dig for food. Stronger tools became a necessity for survival. This era is dated as lasting until about 200,000 BC, through the time of Homo Erectus and Archaic Homo sapiens, the latter now usually called Homo heidelbergensis.”
The climate changed, the savannah spread, Man got taller to adapt to the new hunting techinques needed to survive. Homo Erectus pretty well esablished our current height, being more than a foot taller than previous species & genuses, and was up to 5’5" tall. That is- just enough taller than the grass to stand up and look over it. I am sure there are other possible reasons for the increase in height, but most cite 'changed hunting techniques".
Australopithecus spp, aren’t Humans, they are Hominids. We don’t get “Human” until we get “Homo spp”.
Actually, most plants transport water by a combination of osmotic mechanisms and capillary action. The weight of a column of water is not a restriction (thankfully for the Great Redwoods, or even any tree over 20-odd feet high). More significant limitations (for trees or tall plants) are the ability of a plant to absorb nutrients from the surrounding environment and resist wind loads. A plant’s root ball extends in a square fashion, radially outward (the downward travel is more generally for anchoring and doesn’t offer a proportional increase in water and nutrients available), but moment on the tree also increases as a square function, while resistance to bending increases as a quatric in proportion to the second moment of area (assuming the section to be circular). Point being that, while most plants are able to resist bending along their own lengths for any reasonable proportions, the root ball has to increase in diameter in proportion to the height. Eventually, the root system is so complex and takes so much time to transport water and nutrients back to the trunk, combined with competition against other plants (including, for many trees, its own offspring) that it just can’t grow any larger. This is grossly simplifying and there are many factors, but most non-seasonal plants actually grow as large as they physically can given their inherent structure and availability of resources.
The odd thing with most indeterminate-age plants (specifically, trees) is that, given enough nutrients, they will continue to grow until they reach unsustainable proportions, suggesting that there is no limitation of size imposed by genetics.
The notion that elephants can’t lift more than two legs off the ground (i.e. run in a gallop) is in fact a myth. While their normal gate, and even a fast trot does keep two legs on the ground at all times (owing largely to their forward pointing rear knees) and they can’t deliberate jump, they aren’t in any danger of breaking a leg from running. Larger members of order Proboscidea have been found in the fossil record. A bigger limitation on the size of an elephant is, again, the ability to keep itself fed. An adult elephants spends about 16 hours a day foraging for grass and leaves to feed its diet and probably couldn’t sustain a larger mass. It is in fact this, and not stress fractures or chronic skeletal problems which limits the lifespan of an elephant in the wild.
But in principle, you are correct; while height increases linearly and surface area as a (roughly) square factor, volume (and therefore weight) increases as a cube to height. Larger bodies mean proportionally larger bones, and more importantly, greater stress on joints and ligaments, eventually becoming prohibitive in size. One could concieve of a larger, even gigantic human (say, 5 meters tall), but it would be increasingly squat, to the point of not being able to articulate readily in bipedal gait, and devoting considerable resources to lower skeletal structure and circulatory system. There would have to be a significant impetus to develop this size and I can’t image one. At some point (roughly about the 5m height above) a “hominid” would have to revert to quasi-quadrapedal motion as with the orangutan.
On the smaller scale, the need for flight and respiriation methods of insects prevent them from getting much larger than they are now. Insects breathe by a invaginated cavities where direct exchange with the rudimentary circulatory system meets with air. Such a method would be hugely inefficient for us, but for insects, which have a lot of surface area in propotion to volume/weight, it works just fine.
Proto-human Australopithecus was actually much shorter than 5’ and appeared about 4 MYA, dying out about 2.5MYA or so, with the appearance of H. habilis, which was still only about 4-4.5 feet tall. H. erectus was of modern height, 5ft or taller, appearing about 2MYA. So, many hominids and pre-hominids were successful despite their short stature. The larger stature of H. erectus and subsequent hominids probably had more to do with social dominance, use of heavier tools and carrying capacity, and more predatory hunting habits providing more protein to be utilized. I’d be cautious, though, of assigning any one predominant factor to height. As with all areas of evolutionary game theory, there are various tradoffs which result in a multivariable optimax size, which is not necessarily optimum (for any particular environment or niche) or maximum. We are the height we are because the factors that came into play, combined with previous adaptation, made that a best-fit.
As far as Meganthropus and other H. erectus fossils in Australia, while it does seem unlikely that they were seagoing, it isn’t absolutely beyond the realm of possibility. They were advanced tool makers and evidence exists for their controlled use of fire. Tool-making ability is more than just brain capacity (theirs was about 3/4 of modern human) or even general intelligence, but rather a capacity to communicate, maintain, and improve upon technology through generations. It is just possible that a particularly advanced group of H. erectus could have transported to Australia, thence spread out and diversified, particularly if pressures were high. While the multi-region “mixing” hypothesis has largely been discredited by DNA analysis, there is considerable evidence of multiple waves of emmigration out of Africa (rather than the two waves more traditionally accepted) and of pocket speciation or subspeciation along with competition between different species of hominid.
Personally, I still find Meganthropus unlikely–such a large hominid would almost have to be engaged in animal husbandry or otherwise spend a large amount of time hunting, and for no forseeable reason–but I wouldn’t rule it completely out, even if it isn’t in the current mainstream. The history of hominid evolutionary theory is rife with upheavals, misconstruations, and of course, hoaxes; I don’t think it’s fair to say that any theory, no matter how widely accepted today, is confidently supported by the rather scant fossil history and large inferences we have in our evidence box today.
Stranger
Interestingly, I just did a Google search for pages linking to that Wikipedia article. The one and only hit was Wikipedia’s entry for Bigfoot. I’m thinking that the Meganthropus page was whipped together by a Bigfoot enthusiast, in an attempt to bolster his position. Is there some way to see who wrote or edited a particular Wikipage?
Looking under the “History” tab, it appears that user Lizard_King added the entry, along with entries on Homo erectus soloensis, Yeti, Bigfoot, and Orang Pendek. User Fedor “corrected” the taxinomic name to Homo erectus palaeojavanicus. (You can see the various states by date from the above link.) The discovery and acceptance (if indeed it is as widely accepted as reported by the general media) of H. floresiensis seems to be bringing them out of the woodwork. Next thing you know, Tolkien enthusiasts are going to be claiming that JRR based his hobbits on real creatures, and start plotting out the geography of Middle Earth onto Flores, and so forth.
So, it does look like a Yeti enthusiast, although I daresay that even the existance of Meganthropus would scarcely justify claims of Yeti or sasquach/Bigfoot, any more than the plesiosaur gives justification to the claims of the Loch Ness monster. Some people get way to into this stuff to keep a clear head. Me, I prefer a tumbler of Irish whisky for my reality distortion.
Stranger
But you said “when man stood upright.” If man = the genus Homo, then your statement makes no sense, since the genus Homo has ALWAYS been upright. An upright posture goes back a long, long way-- at least 2M years prior to the appearance of Homo, and maybe even earlier.
I know the savannah hypothesis was popular 20 or 30 years ago, but it doesn’t make a lot of sense in light of recent discoveries.
Well, basically i was talking about the change from Australopithecus spp to Homo spp.
Let’s go over a few facts.
Australopithecus spp was a little guy, not all that “erect”- but very successful. Survived for around 2.5 million years or more.
Around 2.4 millions years ago- the climate changed in Africa. Much more Veldt and tall grass. That also introduced Homo habilis, and was the (drawn out) beginning of the end for Australopithecus. There is no doubt that the climate change broght forth a change in hunting techniques- and apparently these techinques made “taller = better”. One technique was undoubtly the abilty to stand up straight and see over the new taller grasses in the Veldt.
3.Homo erectus came around about 1.5 Million years ago, and was very successful- in fact, he seems to have replaced all other Hominids. He set the "gold standard’ in height for some 1.3 MY, and even afterwards, there wasn’t such a significant increase in hieght until recent times.
So- little guys did fine until the climate changed- the increase in size seems to have been a Darwinian selection for improved hunting techniques triggered by the climate change. One very significant change was much more “talll grasses” -indeed grasses around 4’ tall- and it is very important- if you are a hunter- or even being hunted- to be able to see over that grass. Homo erectus pretty well set human Height. He was up to 5’5", and other than “Giganthropus” and “Meganthropus” (certainly small branches off the main ‘tree’ even if we allow them Hominid or Homo status) that was the last large increase in height until modern man with his great improvements in diet and medicine. (And, if you go back to a staone age diet with stone age medicine (with tribes still extant like that) you go back to being 5’5’ or so, in general. Some exceptions, sure.
Sure- “taller grasses” is a simplification. Doubtless the increase in height had other darwinian advantages in hunting- greater reach, more torque, etc.- but longer arms could have filled those needs. And, other, unknown factors, too likely figure into the greater height. But - from what we know- “taller grasses” seems to be the single greatest impetus to greater height.
Again- if you accuse me of over-simpliciation, you may be correct. There may be a leak or two in my hypothesis, but it’s not a crack pot idea, nor is it my hypothesis.
Yes, little, but why do you say “not all that erect”? There isn’t any evidence that they were stooped. There certainly is evidence that they still spent some time in the trees, and their gait may (big emphasis on “may”) have been somewhat different than ours, but they were certainly erect.
Closer to 1.8M years for Erectus, but that’s a minor quible. The famous Nariokotomi boy would have stood at least 6 ft tall at maturity, and that fossil H. erectus dates to about 1.8M years. The problem is, we don’t have any evidence that hunting, rather than scavanging, was their primary behavior pattern-- especially at 1.8M years ago.
Yes, I know it’s not really “your” hypothesis, as I indicated in my last post. It was, in fact, very mainstream 20 or 30 years ago. But it’s fallen out of favor recently. And, btw, that hypothesis was always used to explain how we became upright in the first place, not how we attained a height of > 5 ft.
And if you think about it, the “taller grasses” hypothesis flies in the face of what we know about every hunitng species on the African savannah-- none of which “stands” 5 ft tall.
Now, I could be wrong, and maybe I’m unfamiliar with the research you are basing your posts on. Is there some reference work you are familiar with that would put that hypothesis forward as what the majority of anthropologists are going by these days? I don’t have an alternative hypothesis to put forward, as I’m not sure there is any agreement as to why H. erectus increased in height-- other than some vague inferences that a better diet and the need to cover longer distances would have provided a feedback loop for increased height.
So- Ok, “my” hypothesis has 'fallen out of favor", sure. That’s about when I was in college and taking all the classes. However- although my reading has only been sporadic since then- the worse thing I have seen said about that hypothesis in the last few years is “over simplified”- which I think I conceded. I still haven’t seen- nor apparantly have you- a better hypothesis put forward to explain the height increase.
My recent sources and reading seem to all assume Homo Erectus was a hunter. of course, without videotape, I don’t think we’ll ever know for sure, eh? 
And, yes, you’re right- the other predators NO LONGER are taller than the grass. They hunt by smell and hearing instead. (Much** prey** is taller than the grass so that they can see predators sneaking up on them). Which means Homo spp filled that niche very well and successfully and became the top predator.
Sandy Hook is right about the “Meganthropus”. That is a fictitious name from the Riverworld series. The Riverworld makers resurected pretty much every hominid with approximately human intelligence. The vast majority were Homo sapiens sapiens, but some were Neandertals. Joe Miller was a 9 foot tall Meganthropus, a currently undiscovered hominid species that had a nose like a proboscis monkey. He was the pal and bodyguard of Samuel Clemens (co-ruler of Parolando and captain of the “Not For Hire” riverboat). Someone was just having fun by adding a fictional hominid species.
Of course there were probably lots of small hominid species or subspecies that we will never know anything about, simply because there never will be any fossil evidence for them.
The reason is that it’s only been in the last 20 or 30 years that we’ve had a clue as to how far back an upright posture goes. When Lucy was discovered (mid 70s, IIRC) and found to be an upright hominid at about 3M years old, that was astonishing. Now, there are strong indications that we’ve been upright for 5 or 6M years-- and that starts to push up against the point where the human and chimp lines branched off. Further, some of the more recent finds in Chad are of species that weren’t savannah dwellers at all.
The other problem is that H. erectus can be a vague term and is often used to cover severl different species (or subspecies) that span anywhere from 1.8M yearrs ago in Africa to 35K years ago in Asia. Most scientists now break up H. erectuc into several different species, reserving the term “erectus” for the group of hominids that ended up in Asia.
So, as far as hunting goes, there is clear evidence of hunting going back ~500k years or so, but it gets murky after that. There were a lot of assumptions about even H. habilis being a hunter not that long ago, but you’d be hard pressed to find anyone pushing that hypothesis these days.
This site gives a pretty good, pretty up-to-date summary of the human family tree, although it doesn’t include the more recent finds like Ardipithecus,
Sahelanthropus tchadensis, and Orrorin tugenensis.
I’m completely convinced that the Wiki page linked to regarding that species is also pure fiction. There was no 9 foot tall, 800 lb *Homo *species.