Surfacin9: Out of Africa: The Origin of Our Species (Part 2)

Australopithecus (ramidus, afarensis, and africanus)

Note: I started reading Africa: A Biography of the Continent by John Reader. The following posts will basically summarize what I find interesting in the book as I’m reading it. None of the ideas or thoughts are of my own.

Lucy, an Australopithecus Afarensis, was found in Ethiopia in the 1970s. This fossil is the earliest known candidate for human ancestry. The deposits in which it was found dates from 3.2 million years ago. Lucy stood at 122cm and weighed 30kg. The configuration of the pelvis and lower limbs tell us that Lucy and her kind walked upright. But also, her arms were long relative to her body size, and her fingers and toes were curved, which indicate that Lucy and her kind retained the ancestral primates’ ability to climb trees. It was very likely that trees provided them an escape from predators, and they may have spent the nights sleeping on top of rocky edges or branches.

Figure 1 - A representation of Lucy in the Smithsonian, Washington, D.C. (Wiki)

While other carnivores hunted from dusk till dawn the hominids slept in a safe place, and during the day they would’ve encountered some carnivores but there wasn’t really competition for food since meat wasn’t as essential to the omnivorous hominids. For hominids, a little meat provides enough proteins for quite a while, and too much of it is not that healthy. If protein consumption exceeds 50% of the daily total calorie intake for a prolonged period of time the liver function will be seriously strained. This is especially true when the meat consumed is low in fat. Consumption of purely lean meat would kill a human within weeks!

Fat is essential to good health. Most game that roams the African planes are very rich in protein, whereas most of the fat is found in the braincase and marrow of the animals. It’s very possible that hominids looked for bones and carcass more often than the flesh to fulfill the necessary intake of fats. The prey’s marrow and its scull tend to be left after the predators consume the meat and after the scavengers pick at bits and pieces that were left, which gave hominids the chance to get to the needed fat. Besides, plant foods constituted the main part of a diet; they are pretty rich with proteins too, so the fat intake from game was sufficient for the purposes of the hominids if game meat was too difficult to get to. However, at migration sights meat was plentiful, so this is most likely where the ancestral hominids’ pre-adaptation towards a bipedal mode of locomotion was gradually adopted.

What’s fascinating about our ancestral hominids is that from the 5 million year old australopithecine (the oldest known), to Australopithecus Ramidus (existed 4.4 million years ago), to Lucy (3.2 million years ago), and on to Australopithecus Africanus (2 million years ago) (Figure 2), represents a span of about 150,000 generations without any physical change that would indicate a significant shift in the way of life. They were nomads that walked the old African continent, moving towards whatever they could feed on, and away from whatever they needed to escape; day in and day out. It seems that the generalized (as opposed to specialized) form and lifestyle of these small bipedal primates functioned successfully in various climatic and ecological conditions within those 3 million years.