Evolution
(This was originally published on www.pintofscience.com )
Evolution is the answer to nearly all the how and why questions in biology so it’s well worth having a bit of a swot up on it in case anyone challenges you to a science duel. Here’s how it works in 5 easy steps.
Competition
More offspring are produced than can possibly survive. It’s sad guys, but it’s true. This creates a competition for survival. Darwin’s thoughts and understanding about this were influenced by the writings of Thomas Malthus.
Variation of offspring
As anyone who has had more than one kid can tell you, they vary. Little Jemima might be grade 10 in violin, but little Horace can’t even play 3 blind mice on his little plastic recorder*.
And so it is the same in the rest of nature, some kangaroos can jump higher and faster than other kangaroos, some barnacles are better at sticking to the rock than others and some peacocks have such sexy tail feathers they are nigh on irresistible.
This variation is caused mutations in the genetic code which can be deleterious or advantageous.
Fitness & Natural Selection
The fact that offspring vary means that some are better adapted to survive than others — they have a higher fitness and are therefore naturally more likely to survive to an age where they can reproduce. This is called natural selection.
There are other types of selection too — sexual selection (remember the sexy peacock?) and artificial selection (that’s all to do with farmers and people who are determined to win at Crufts)
Inheritance
Those that are better adapted to stay alive are more likely to reproduce and have their own offspring, which in turn are likely to have inherited some of their advantageous attributes.
Time
Over thousands and thousands of generations this process causes species to change and adapt to different conditions and niches. Eventually new species develop.
FAQs
So, its everyone for themselves then?
Evolution is a process, not an ethical code, so unfortunately you will still have to be responsible for your own behaviour. Some people misinterpret the fact that evolution has shaped animal behaviour (including human behaviour) as supporting the idea that whatever behaviours are “natural” are the “right” ones. This is not the case. It is up to us, as societies and individuals, to decide what constitutes ethical and moral behaviour. Evolution simply helps us understand how life has changed and continues to change over time — and does not tell us whether these processes or the results of them are “right” or “wrong”.
Well, if evolution is so good, how come everything isn’t perfect?
Evolution does not work towards perfection. It does not work towards anything. Evolution is a process. It does not have consciousness. Mutation is random and selection is only for individuals and populations that can survive long enough to reproduce. This is the reason why things start going wrong after the age of child rearing has passed and why genetic diseases like Huntington’s Disease and dementia have slipped through the evolutionary net.
While we are here I should also probably explain that not everything is an adaptation, some biological features are vestigial which means that at some point in our evolutionary past they were useful but they are not useful any longer. For example; wisdom teeth in humans and eyes in some deep sea fish. Some non-adaptive traits are linked to adaptive ones, for example the genes which cause sickle cell anaemia give carriers a resistance to malaria.
I hope that clears things up for you and that you are victorious in any future science duels.
*I can neither confirm nor deny that musical ability is influenced by genetics. Perhaps Horace just needs to practise more.
