Somewhat similar questions have been posed before, but what I'm really interested in is what selection pressures would be necessary to produce a subspecies of giant humans, about three meters in height. In asking this question I am making several assumptions:
- Humans can climb trees, and therefore would not benefit from growing in size in order to better harvest food from trees as giraffes did, for instance.
- Humans are relatively clever and highly social pack hunters, and so can hold their own against the average predator. As a result, they are already safe from most predators, including predators stronger than them, and would not necessarily benefit from growing in size.
- Humans are mobile, and therefore will simply move away if they live in an environment wherein averagely-sized individuals are dying at high rates.
- The environment which this theoretical branch of humanity lives in is capable of supporting the dietary needs of these giant humans.
I think it's worth noting that gigantopithecus managed to reach about three meters despite there being no obvious benefit to this increase in size, so while I'm not really sure if all the above assumptions hold true in the case of gigantopithecus, it does illustrate that gigantism can occur viably in homonids, so I'm assuming it's theoretically possible with humans as well.
What kind of pressures would result in giant humans under these terms?