Saturday, April 17, 2010

Australopithecus Sediba: Why Every Bone is Good

Another new hominin has been published, in Science, discovered by Lee Berger and his team in South Africa some while ago, and now revealed to the world. The article is here, and is worth a look if you share my interest in where we come from (I realize not everyone does, some people are odd like that).

Southern Africa means we expect it be Australopithecus africanus, and indeed it has been assigned to Australopithecus, but has been called Au. sediba, a new species (sediba means spring in Swahili, I am informed, and it was found near one). As to why it's not Au. africanus, why it hasn't been placed in Homo, what it actually is and what it tells us about human evolution, I will leave it to John Hawks, who is the man to go for this stuff, and, to a lesser extent, these people, to do the honours.

Why is so little known about human origins? Why does every new set of bones seem to belong to a new species, and to require a severe restructuring of the family tree of our species?

I said something about that here, but now I want to offer an explanatory metaphor. Imagine that the origin of man is sewn into a tapestry of great richness and beauty, several yards on a side, filled with images and designs picked out in a great variety of colours and the most exquisite detail, coming together into a complete and coherent whole which can only be truly appreciated from a distance of many feet. Imagine that in front of that tapestry is hung a white sheet. Every so often a pin is stuck through the sheet at a randomly chosen point, leaving a tiny hole. An observer is permitted to look through these holes, moving from one to another as he wishes, but is not allowed to move the sheet aside, and cannot influence in any way the rate at which the holes are made or their placement.

We are in the position of that observer, trying to conceive what the great picture might be from a few tiny glimpses, randomly distributed in time and place, and with almost no clue as to what may connect one image to the others. Every new piece of information gives us new ideas about the great picture, which can only be tested if the next pinprick just happens to come in the right spot.

One day we will know more than we know now. That's about all you can say.

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