<HTML>Yup,
seems to be a bit of a sieve theory...
But I'm sure that the programme was selective with the evidence both in favour of and against the hypothesis being proposed - the Beeb doesn't trust us to be able to handle too much information in one go.
Maybe there are reasons mitigating against migration at time of drought, or maybe there was no drought - from the evidence presented in the programme we can't really make up our minds....
I was heartened, though that the guy proposing the theory - the ex-banker - had at least bothererd to study archaeology before getting involved with the Maya question.</HTML>