Friday, 24 July 2015

Macroevolution can happen

Macroevolution - the formation of a new species in one generation is extremely rare in animals, but more common in plants. The way it can happen is through duplication of the entire genome. Organisms which have multiple genome copies are called 'polyploid'. In some plants it's possible to trace back exactly where and when these things happen. For example, a new species of marsh grass appeared in a certain area of marsh in Britain in around 1870. This would have been one faulty cell division resulting in a new species. 

Animals are much more complex in structure than plants and rarely reproduce asexually so this kind of thing is much rarer, but it does happen - the plains viscacha rat in Argentina is one example. What must have happened is a faulty cell division leading to a polyploid female and then inter-breeding in her offspring.

Tuesday, 7 July 2015

How 'gay genes' might work

This business of 'gay genes' seems to me to be almost universally understood. First of all, they must be inheritable. Homosexuality can't just be a frequent mutation - it's too widespread. Secondly, they have to confer benefit to those who have the genes, and that's just about everyone, because homosexuality occurs in all populations. So how on Earth could that work? It works if you consider homosexuality to be part of an 'extended phenotype' (see the book 'The Extended Phenotype' by Richard Dawkins): genes for homosexuality don't produce homosexuality in the bodies they are in, but in others. That allows them to be inherited.

Imagine a group of animals that can end up living in dense populations. What would be a bad thing is for the breeding pairs to continue to produce large numbers of breeding offspring. Instead, when resources get limited, a better situation is if some children don't breed but end up helping their parents to raise their siblings. Does this happen in Nature? Yes, it does. A very clear example is some species of birds, where non-breeding young birds help their parents get food for their siblings. This division of labour into breeders and non-breeders results in a better chance of survival.

This must mean that the parent animals have genes that allow for the production of non-breeding offspring in certain situations. Not all offspring of course, but a certain proportion. This might happen because hormones react to population density. The point is that genes for non-breeders can exist throughout the population, and can be of real benefit.

There is slight evidence of a similar situation in humans. Later children in a family seem to be more likely to be homosexual. This makes sense, as the family has already produced breeding offspring, and what might be of more use is additional resource gatherers. This seems to work because the hormonal environment in the human uterus changes with each subsequent birth, and that might increase the probability of homosexuality.

This may be wrong, but it does show that genes for homosexuality don't need to act in the bodies of homosexuals - they could simply be genes that change the hormonal environment in the uterus with time. Also, homosexuality can be of real benefit in a population at low levels, as it provides additional support systems for families - even as simple as more hands to gather food and fight mammoths!

There is not going to be a simple 'gay gene'. The situation is far too subtle.

Saturday, 4 July 2015

Obama's eulogy of little grace

Obama's Charleston eulogy was certainly a great performance. It was moving, and I have no doubt it was heartfelt, but I was deeply saddened to see that he was preaching so much religious nonsense that I could not help but feel took away some of the dignity of the deceased.

It was a shameful thing to preach that the killer was somehow doing God's work, and that God works in mysterious ways.  There is nothing holy about the actions of a hate-filled cowardly murderer. It was demeaning to talk of God-given grace being given to the undeserving members of the Church as well as to the USA as a whole.  It was a denial of the true wickedness of the murder and of the powerful humanity of that community.   The families of the murdered and the community they lived in have shown extraordinary strength and courage.  It is their own strength, not some power of the spirit bestowed on them.  These people have shown the best of humanity - they have stood up for themselves, they did not need to be lifted up by God.

It was a shame that, giving the eulogy in front of such a courageous community, Obama didn't have the courage to praise that community for what it had achieved without invoking the name of a God who stood by while hatred killed so many good people.

Obama gave a powerful speech, but to me, it was a failure.