Anthropologists have different opinions about the proportions of plant and animal foods consumed. Just as with still existing hunters and gatherers, there were many varied "diets" - in different groups -of fruit and vegetables. The relative proportions of plant and animal foods in the diets of Paleolithic people often varied between regions; in colder regions, more meat was necessary. These regions were not populated by anatomically modern humans until 30,000-50,000 BP. It is generally agreed that many modern hunting and fishing tools, such as fish hooks, nets, bows, and poisons, were not introduced until the Upper Palaeolithic and possibly even Neolithic. The only hunting tools widely available to humans during any significant part of the Paleolithic period were hand-held spears and harpoons. There's evidence of Paleolithic people killing and eating seals and elands as far as 100,000 years BP. On the other hand, buffalo bones found in African caves from the same period are typically of very young or very old individuals, and there's no evidence that pigs, elephants or rhinos were hunted by humans at the time.