quote lbt10The selective pressure is on both sexes actually. It isn't just for males carrying food to the females, but also the female carrying her young, and food and being able to carry food from its source to a more protected area. Even in sexually dimorphic species males are still often called upon to tend to the females. Sexual dimorphism does not rule out behavioral pressures. Chimpanzees today are sexually dimorphic, yet the males still aid in the minimum parental investment period by protecting the females and aiding in their ability to find and gather food.selective pressure for bipedalism is only put on the males for carrying food. Also this implies a paired lifestyle (one male one female) but Australopithecus, the first bipedal hominid, was sexually dimorphic (so one male multi female). Therefore saying that males evolved bipedalism to carry food is null because they would have to be transporting it for many females.
quote lbt10I too believe that it is an amalgamation of the different theories but why does thermoregulartory control convince you the most? Austrolopithecus also lived in wooded areas and grass lands, not so much in rain forest environments. The rain forest environment was drying up and becoming open grass lands and forests like those in Europe and America. This is one reason why the behavioral pressure is actually thought of, their food became less plentiful and was no longer the soft fruits of the rain forest but fibrous and grassy foods of the plains and forests. The less availability of food would be more pressure to travel farther distances to gather needed resources with could be a pressure both to evolve an efficient means of locomotion as well as a means to transport those resources back to a safer place.There are 7+ hypothesis for bipedalism and I think that more than one was the factor in it. Thermoregulatory control convinced me the most, however Australopithecus lived in a rain forest type environment. The answer may not be clear at this point, but I sure hope we get close.
quote StefanActually there are many monkeys and primates that are stronger than humans. Gorillas, orangutans, chimpanzees, bonobos, all are stronger than humans. (though I admit the bonobo does seem far less dangerous. They are so adorable and lusty!) Many carnivores as well do understand numbers. Lions hunt in prides, hyenas, jackals, wolves, etc. They all use numbers to their advantage to single out a prey and take it down. Orangutans would actually go against this idea as well as they tend to live in isolation except for mating. Intelligence was also not our first hominin trait, bipedalism was, thus my fascination with it. Our intelligence and brain size only came after we were bipedal.Intelligence itself gave us our edge. Monkeys and primates in the jungle now are hardly as strong or as dangerous as the average human but they live in packs, feed, wash, mate and live together. Maintaining a community that protects each other.
There are many animals that can bring down a man or a monkey, but few that understand the significance of numbers.