July 13, 2004
STILL?:
Are we still evolving?: Modern medicine has eliminated many previously lethal hazards. So has evolution come to a stop? (Gabrielle Walker, July 2004, Prospect uk)
Charles Darwin's theory of natural selection struck a body-blow to human hubris. We were not, after all, an elevated species, untainted by the vagaries of nature. Instead, we had obtained our exalted powers in the same manner as all other living things - through fortuitous evolutionary adaptations to a natural world characterised by what Darwin called "blind, pitiless indifference".
Natural selection works on us because millions of random mutations occur in our genetic blueprint between one generation and the next. Suppose one of those gives rise to a trait that enhances your capacity to survive some environmental hazard; you live in the tropics, say, and a genetic mutation means that you are born with slightly darker skin than your parents. In that case, you will have a slightly better chance than your paler peers of coping with intense sunlight, and hence surviving to have babies of your own. It is through this incremental matching of mutations with environment that people from the tropics have browner skin than those in cooler climates.But evolution has equipped us with inventive minds that let us mould the environment to our own specifications. We can eliminate the hazards and leave evolution nothing to work on. As we daub ourselves with sunblock creams, there is no longer a selective advantage to brown skin, and asthma, which used to be a killer, has become a mild inconvenience.
It is easy to argue that many, perhaps most, of us would not have survived to pass on our genes without the benefits of modern technology. Now that we have eliminated many of the worst infectious diseases from our cities, some even say that we are no longer subject to the destiny of natural selection. For 21st-century human beings, could evolution have come to a full stop?
Hard to believe the coincidence that evolution stopped at the precise moment in time that we began trying to observe it, eh? Posted by Orrin Judd at July 13, 2004 8:30 AM
Whether or not evolution has stopped, sexual
selection has not, and neo-eugenics is gaining
credence as an idea.
With the widespread use of abortion and birth control, selection for the desire to have children is occurring. We don't know that there is a genetic component, but there could be for all we know.
Posted by: Robert Duquette at July 13, 2004 1:21 PMThink of all the money we could save on
Orthodontics and Optometry!
Orrin, please see your own posts re: AIDS.
Posted by: Harry Eagar at July 13, 2004 1:45 PMCulture, what is learned and passed on, is subject to evolution--to variation and selection. The human mind does not end evolution, it IS evolution. Should we not say that the technology of producing either sunscreen or warm clothing at need and choice is of greater utility toward survival than either melanin or subcutaneous fat? Mere physical evolution can take the organism into an evolutionary dead end; cultural evolution continues to reward adaptability. Herbert Spencer, where are you now that we need you?
Posted by: at July 13, 2004 2:04 PMAnon:
Yes, that's where Darwin got confused to--complex systems made up of innumerable decisions by intelligent beings are indeed evolutionary.
Posted by: oj at July 13, 2004 2:55 PMWith regard to whether there is a genetic component
for the desire to have children, haven't you ever known a single woman in her mid thirties obsessed with the ticking of her biological clock?
From a theory point of view, what could be more fundamental to evolution than a genetic desire to have children?
Because AIDS is capable of wiping out human groups. Not all, but some.
That's natural selection in action.
Posted by: Harry Eagar at July 13, 2004 8:54 PMNo it isn't.
Posted by: oj at July 13, 2004 9:05 PM