Exhibit A: Gold. Archaeologists aren't interested in it. They are not only not interested in it, but are more interested in broken potsherds. Compare this not just with the world today, but with the whole of human history. Entire economies have collapsed for the lack of gold, individuals have committed murder or suicide for it. The wretched stuff is the basis of proverbs, children's adventure stories, damnation in the next life, epics, myths, films - whatever.

You would think it inconceivable that anyone would find gold, as archaeologists occasionally do, photograph and draw it, stick it in a finds bag and then carry on digging - relieved that the hold-up is out of the way. Back in the finds shed at tea time, if archaeologists were normal you might expect to find blue-faced finds assistants lying dead on the floor with bruising round their necks. But it just doesn't happen.

Exhibit B: Death. Archaeologists are not just interested in death, they go to conferences about it. They read books on it and study photographs of skeletons. Churchyards are swarming not with mourners but with archaeologists. Yet out in the real world, discussion of death is taboo, everyone has their own specific to ward it off, hospitals are determinedly jolly - mention death and they send you home - and hearses scurry by unrespected. If the public really knew what archaeologists got up to with the dead there would be an outcry.

Exhibit C: The future. Archaeologists use the future tense only when saying things like 'I'll be working on a Neolithic site next year'. The future simply means more developments, sadly, and so more archaeology. The world, however, is well into tomorrow. The real shrines of the future are hairdressing salons with their compulsory discussions about weekend plans, holiday plans, Christmas plans etc etc. Avoiding them is the main reason why archaeologists are not noted for their hairstyles.

Exhibit D. Mystery. Archaeologists have no time at all for mystery, for spine-tingling hunches and all that palaver about the past that fills our culture. While the world talks about the spooky secrets of the past, the archaeologist gets out a tape measure.

Exhibit E. Rubbish. Archaeologists revel in it, while the real world rings up their local councillor if they see a scrap of it on the pavement.

One could go on but it's clear enough that archaeologists as a profession are not just different from the rest of the world in their attitudes, but are actually a different species from humans altogether. The inescapable conclusion is that archaeologists all come from outer space.

Now, I've checked my birth certificate and it says 'born in Basingstoke', which I still remember - how could I forget? - so becoming an alien must have taken place later on. Clearly this occurred for each of us on our first contact with archaeology. After all, everyone interested in archaeology has a story to tell about how they first got hooked - not realising that this was the moment at which they were taken over by extra-planetary forces.

You may still be unconvinced and ask, Why? The answer must be that the profession of archaeologist was invented by researchers from another solar system as the only way to find out about the past of this curious human species. It must have been just over 100 years ago that they came to Britain. They read The British Constitution, Our Island Story and A Cavalcade of Kings and, unsurprisingly, could make neither head nor tail of it. They realised that they had to start anew and so they alighted on their first catch - General Pitt Rivers. The rest is archaeology.

As is well known, our intricate, complicated and labour-intensive site reports are not read by anybody on this planet - but that's because their purpose is to be studied out there somewhere. And this also explains why archaeologists are so completely different from everyone else in world history. We have to be, to trowel away in the rain, or study in the loft extension, for neither money nor fame. Though who knows what honours we have in store for us on Planet Zog?