Sunday, March 9, 2008

The Myth of Terra Stasis

I never seem to actually take pictures of the things I end up wanting to talk about later. Last week I was just outside of Broken Hill, walking around some splendid desert landscapes at a place called the Living Desert. I took lots of pictures of plants for a post I will possibly get around to writing on convergent evolution, but I didn’t take a picture of a set of brush shelters, nor of the sign describing them.

You will have to imagine that if you turned around from where you were standing and seeing this, there they would be, looking quite shady and inviting at that hour of the afternoon.

The sign describing the shelters did something that is relatively common in things written about Aboriginal culture for popular consumption but which always irritates me as a pedant.

It said something like: ‘The Wiradjuri people have used shelters like these for 20,000 years.’

This cannot possibly be true.

It is sloppy shorthand for two things that are almost certainly true:

(1) The Wiradjuri people used shelters like these.

(2) Traces of shelters like these have been found dating back to 20,000 years in this area.

It should say: ‘The people of Wiradjuri country have used shelters like these for 20,000 years’.

If you were in Spain and you saw a sign on a replica shepherd’s hut that said ‘The Spanish people have used shelters like these for 5000 years’, you would automatically read ‘Spanish people’ as ‘people who lived in what is now Spain’, and think it was a bit of an odd way of putting it.

Here is a worse example, as near as I can remember it, from a newsletter put out by my old university many years ago:

‘The original meaning of these images [in 4000 year old rock art in the Chillagoe region of North Queensland] is unknown because the Aboriginal people of the area were removed to Palm Island and their stories were lost.’

It is a very real tragedy that the stories of these people were lost. But there is no way they had any idea of the ‘original meaning’ of 4000-year-old images. You wouldn’t dream of writing:

‘The original meaning of the Uffington white horse is unknown because the villagers of the area were removed to make way for a motorway and their stories were lost.’

We know that the oral history of England is not trustworthy over thousands of years. We know that peoples have come and gone, and that there is no real memetic link between the people that made the Uffington white horse and the people who happened to live near it in the 20th century.

Why should we believe the oral history of North Queensland could be trustworthy over thousands of years? Why should we believe that peoples have not come and gone, and that the people who happened to live near Chillagoe in the 20th century had any memetic link to the people who lived there 4000 years ago?

These are only two examples of the denial of Aboriginal history.

Here is a third, which is not just of interest to pedants, because it means potentially interesting and important science is being ignored.

I was recently at Lake Mungo National Park. The visitor’s centre made no mention at all of the controversial mitochondrial DNA studies that appear to show that the 40,000 year-old ‘Mungo Man’ remains are genetically distinct from all modern humans- something that I had heard about and was keen to know more about.

Instead, there was stuff along the lines of what is quoted in this article:

“Non-indigenous Australians too often have a desperately limited frame of historical reference. The Lake Mungo region provides a record of land and people that we latter day arrivals have failed to incorporate into our own Australian psyche. We have yet to penetrate the depths of time and cultural treasures revealed by those ancestors of indigenous Australians,” [Prof Jim Bowler] says.

“The messages from the ancient Mungo people challenge us to come to terms with the history and dynamics of this strange land, especially with the rights and richness of their descendants.

“Indeed it is those descendants, in the person of the three traditional tribal groups of the Willandra region (the Barkandji, the Mutthi Mutthi and the Nyampaa) who facilitated and cooperated closely with this project. This represents an important new phase in the collaboration between science and traditional owners. Science and the Australian community owe them a special debt of gratitude.”

If you were excavating 40,000 year-old remains in Spain, you wouldn’t expect them to shed any light on the ‘rights and richness’ of present-day Spaniards. Pretending that the present inhabitants of an area that has experienced dramatic and extensive climatic changes necessarily have memetic or genetic links with the people who lived there 40,000 years ago is not endearing and culturally sensitive.

It is unscientific. It is deeply irritating to pedants. And what is more, it is insultingly patronising.

The Aboriginal population were not part of the scenery, waiting around in the same place doing the same things for thousands of years so that white folks could turn up and history could begin. They had a history that was surely every bit as rich and interesting as the pre-Colombian history of North America. People moved around. Cultures changed. Peoples replaced other peoples. Interesting history happened. We don’t know what it was, and to a large extent we can never know. We have yet to ‘penetrate the depths of time’. But it is an important and interesting part of human history that I would love to know more about.

Update: I went back two years later, and here they are:

Things I learned in Canberra

First, there is mitochondrial DNA.

All eukaryotes have mitochondrial DNA.
This DNA codes for things that are useful in mitochondria.
This set of things, however, is different across different species.

Over all species, however, there is not one thing useful in mitochondria that is not coded for in nuclear DNA.

Second, I learned that there is extremely good evidence for transposons acting to transfer a beneficial characteristic from one species to another- specifically, to transform an inert species of fungus into a wheat pathogen. I always thought this sort of thing was a theoretical possibility, but I had never heard any good evidence of it happening in eukaryotes before. Voila, it happens!

Third, I learned that I need to learn a lot more about plants.

Green plants are more complicated then us. They have larger genomes, on average, and have chloroplasts with their own DNA as well as mitochondria with their own DNA. They make an awful lot of things that we have to get by eating other things, so they have more complicated metabolic pathways. Our sense of how natural selection works is also skewed by us usually thinking of animals rather than plants, despite all that rigmarole with peas back in Mendel’s time: one animal individual crosses with one other individual to make some offspring. But consider your typical tree, covered with gazillions of flowers: it is more like one individual crossing with the whole population within ever so many kilometres to make some offspring. Actually, don’t a lot of animals in the ocean do the same sort of thing?

I learned specifically that I need to learn more about the immune system of plants. It seems plants have no acquired immune system. Each plant cell is autonomous, and just has the genetic potential for immunity that it started out with. A plant can’t acquire antibodies to something new and strange the way we can. (Memo to self: how do we actually do this, again? I need also to revise what I sort of kind of once knew about the immune system of us.) You would think, without any acquired resistance, plants would need a rapid turnover of generations to have any chance of adapting to pathogens. Sure, a lot of plants do seem to have a rapid turnover of generations. Yet, we have these things called trees that live for hundreds or thousands of years. How do they do it? They are likely to be facing a completely different pathogenic environment at the end of their lives than at the beginning. They are supposed to have no more resistance than what they were genetically programmed with.

Action: Learn about the molecular biology and evolutionary biology of plants. It is interesting.

I ought to point out that Marco's thoughts about evolution were rattling about in my head while I was learning these things.