I am the next stage in human evolution
I've been thinking about genetics recently. I have red hair and fair skin (if I were any more pale I would be transparent). As well as giving me a fiery temper, the red hair gene reduces production of the skin pigment melanin, which provides protection from the sun. Consequently I burn easily, and the closest I ever come to a tan is when freckles join up. This may make you wonder why such a trait would ever exist in the population.
It turns out that the red hair gene is advantageous because red heads can produce more vitamin D from sunlight. Which is why red hair is common in north western Europe. If the gene had occurred in Africa, then it is unlikely to be passed on since carriers of the gene would have succumbed to skin cancer before adulthood. I find this interesting because it is a recent addition to the human genome. For the creationists in the audience, it is a gene in human beings that has come about through natural selection (go Darwin, it's your birthday)! I suspect that if human beings didn't move about so much my descendants would evolve in to the lesser-spotted red human, common in northern areas.
My girlfriend has a very different complexion to me. She is Brazilian, with ancestors from Italy and Portugal. Her skin is darker than mine and tans very easily. She also has other adaptions to a sunny climate; her skin always seems hotter than mine, as if her body favours getting rid of heat rather than conserving it. And she will shiver and get goose-bumps at temperatures that I find comfortable. I can see us fighting over the thermostat!
The red-hair gene is recessive, so a child must get it from both parents to have red-hair. Which means that if Maria and I have children (patience sweetheart), they are unlikely to have red hair since she probably doesn't have the gene (our kids will probably look like this). I'm actually quite relieved that my kids will look more like her. Hopefully they also won't also inherit my unmanageable hair and allergy to house dust mites.
This makes me wonder if evolution in human beings has effectively been halted? We are no longer constrained by geography in the way the rest of the animal world is, and most people will get the opportunity to pass on their genes. Will human beings evolve in any significant way in the distant future? I suspect not. There are plenty of species that seem to have stopped evolving, because they occupy an evolutionary niche. Disappointing really, I wouldn't mind a philips screw-driver for a pinky finger.
