How can humans evolve ?

Question

Throughtout millions of years, the human species has been changing and evolving - how can this continue if every time a person is born with an "abnormality", we "fix" it and change ourselves for reasons of vanity?
If we don't let ouselves adapt and evolve, how can the human race survive?

Answer 1

I thought about that once too... Man cancelled all the natural selection (except, off course, the things that inevitabilly lead to death). People with genomic defects get fenotipically (but nort genotypically) fixed, so they can reproduce as all the other, leading to the propagation of the "abnormality".
On other hand, it's obvious that we can't let a person, just because he/she has a different (but less adaptative) characteristic, live (or die) without assistance or medical care, in sight to provide a better (or normal - which may include reproduction) life condition.
Human species evolved so much that it got the means to stop it's own evolution... ironic... but it couldn't be other way
Good question btw

Answer 2

gribblin is exactly right. The things we can "fix" are just a tiny fraction of the total variation (good and bad) in the human species. So human evolution will continue ... in fact, we couldn't "stop" human evolution if we wanted to.

Also, if it's something we fix "for reasons of vanity", then you are saying that it has no real survival purpose ... and if so, by definition, would not affect evolution anyway (since evolution is about survival to reproduce).

But the vast majority of the things we "fix" are to allow a human being to lead a decent life. Helping fellow human beings is a higher priority than evolution, any day.

For example, I was born with a congenital defect in my stomach (called pyloric stenosis) that would probably have killed me as an infant. A simple bit of surgery allowed me to survive and I haven't had a single problem since (the only sign of it is a small scar on my belly that I've had all my life). That may mean that my survival allows me to pass that gene onto offspring ... but I'm glad that wasn't part of the decision. :-)

Answer 3

The abnormalities that we fix (or at least that we attempt to) are detrimental abnormalities.
There will be other "abnormalities" that we just haven't noticed. Maybe someone is *slightly* better at athletics because their haemoglobin a slightly different. We don't perform genetixc tests on athletes to identify the mutations they might posses.
Similarly, there are people who appear to be immune to AIDS: they can contract HIV, but the virus never attacks their immune system. If AIDS does become more widespread (not that it's a small problem now, you understand...), and we are unable to cure it, then people with these mutations will become more common.

We are stopping the "bad" traits from disappearing entirely (though recessive traits never would), but we are not effecting the beneficial traits. So we will *still* evolve.

Answer 4

Humans do not evolve.

Darwinian evolution would require the creation of vast amounts of new genetic information (for example for a fish to grow legs, of lizard to grow wings.)
The proposed mechanism for this is mutations, acted on by natural selection.

But as you have alluded to, the fact of the matter is tht *all* observed mutations are either information neutral or lossy. They often result in harmful effects.
What we actually observe is devolution.

The best that evolutionists usually come up with is sickle cell anemia - this mutation gives some survival advantage in some places since it stops you getting malaria. But the mutation is lossy, and having sickle cell can hardly be described as upwards evolution!

The same is true of other quoted examples such as wingless beetles and blind fish - both variants can be beneficial in some circumstances but they involve information loss.

Answer 5

We are still evolving. The "selection pressures" on our species these days are largely social. Consider: in developed countries, women with educations and careers have fewer children than women who don't have those. If this trend continues, then in the future, girls will be less interested in education and careers. This might manifest as a decrease in the intelligence of the species.

Answer 6

you bring up a good point which is what impact to humans have on their own evolution (as well as other animals) that we weren't doing before technology came around.

I'm sure humans have a huge impact, however, we are still undergoing evolution. The rates may change, selection may be altered, but it's still evolution.