How would natural selection in humans speed up?

Question

We are living longer and longer, more diseases are being cured, and it is becoming easier for disabled people

I've heard that natural selection in humans is speeding up. Is this just a long term trend (thousands of years)?

Answer 1

What do you speed up??

Answer 2

Well, actually the lack of natural selection is allowing some physical traits to be more common.

Near-sightedness, and tall people are two examples.

Before civilization, near-sightedness greatly reduced your effectiveness in hunting, so you had a higher chance of dying. Taller people also had a higher chance of starvation, as they require more calories to stay alive, which was a problem during droughts (famines were very common in the past).

Answer 3

It's said human evolution is speeding up. Given more and more people and medical advances there's more variation among humans.

"The question of whether modern humans are evolving has not gone away, though. Scientists recently added to a growing pile of papers that indicate human evolution is not only continuing, but may be accelerating at an unprecedented pace. "

http://www.thehindu.com/seta/2008/01/31/...

"if you're breeding livestock and want to select for some characteristics, it is important to select from as large a herd as possible, because large populations have more variation in them."

http://johnhawks.net/weblog/topics/evolu...

"When I was in school I learned that human evolution had ... A lot of people were saying that, especially in the 1960s.... What people were not considering is the demographic change. There are so many more people that the chances for really favorable strong mutations becomes very high. That's an old idea. Its something that Darwin pointed out, if you have lots of individuals you could have rare mutations that were advantageous. "

http://www.archaeology.org/0803/etc/conv...

Answer 4

As already mentioned, natural selection is not something that occurs at any kind of rate because it is not a "process".

Evolution is, however, a process driven by "natural selection", which acts more as a force.

Therefore, natural selection can't be discussed as something that "speeds up".  At most, the effects of natural selection may become more apparent or observable?

I suppose since Darwin's ideas of "natural selection" were based on Malthus' work on population dynamics, the effects of competition will be clear as populations grow and food becomes less available.

Things like disease are population checks.  These "checks" effect populations and so only indirectly effect competition, or natural selection.  Disease is not a good indicator of natural selection because natural selection implies competition.

Answer 5

Natural Selection does not have natural rhythm or rate.  To say that it is is speeding up or slowing down is meaningless and to claim that it has stopped is preposterous.  It is not, as some people seem to think, a constant, but something which occurs with no pre-defined periodicity (despite the fact that some of the most significant selection events - mass extinctions - have an astronomically influenced regularity of between 40 and 55 million years).  

Longevity and other 'quality of life' issues have little to do with selection.  Selection operates at the level of the species, not the individual and not the society, and the key variable is reproduction, not lifespan, happiness, or even overall health. Since most humans can't reproduce until about the age of 13, and since reproduction at that age is so often unsuccessful, we are biologically disadvantaged by our own developmental cycle when compared with many other species.  The flip side of this, however, is the fact that the evolutionary success of our species only requires that individuals live long enough to reproduce successfully (13-25 years, generally).

Our cultural, intellectual and technological development, of which we are so often proud, may or may not have anything to do with our species' ability to carry on. Evolutionarily speaking, we are a relative new-comer and an unproven creature. Depending on whether or not you think Homo sapiens neanderthalensis is part of our species, we have only been around for - at most - a couple million years.

Answer 6

In fact, it is slowing down. Way down. For example, if two people with high blood pressure produced children with the same defect, the high blood pressure would eventually terminate that family line until the blood pressure problem no longer existed. But with medications, the high blood pressure is controled and that same family line keeps going. And any additional defects that appear in that line are kept active too.

Answer 7

The military is worried about speeding it up by putting men and women together in Army tents and Navy ships. LOL

Yet, they are doing it, so I guess, natural selection wins again.

Answer 8

I can tell you how Un-natural selection would speed things up!

Two words: Genetic Engineering!

Answer 9

I think what you heard was that the MUTATION RATE was speeding up and has been since the advent of agriculture.

Answer 10

No, natural selection is not speeding up. For natural selection to cause more rapid changes in humans, many of us would have to be wiped out very quickly. Such as by a plague, for instance, in which only a few of us were immune, say, all people with blue eyes. This would mean that blue eyes would rapidly become the norm.

People who are genetically disabled either have a low reproductive rate, either by choice or by being infertile, or by not being able to find a mate, or they become disabled in such a way that it is not genetically inheritable, such as by accident, so this would not affect natural selection.  

Natural selection could be considered to be slowing down in the sense that, in western society, families are smaller, but in underdeveloped countries, families are still large, children still die from common diseases, and selective pressure to adapt is still present.

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Answer 11

I do not beleive in evolution.

I beleive in book of Genesis, the Biblical explanation of humanity. But I do beleive people adapt to their environments---whether naturally (by this I mean, picking people or mates with desirable physical traits to pass on to future generations and  genetic mutation--new beneficial traits popping up) or humans learn new things and use their knowledge to increase their chance of survival.

I do not believe anything is speeding up. I do beleive the world is getting smaller, in the sense that everyone is connected via the internet and higher forms of technology. I think news is traveling faster than ever before.

I would not worry about human kind. Just focus on yourself and work to better yourself, your community, and things will be A O K.

Answer 12

We would have to live like the Pilgrams did.

No heat,electricity,and hydro, for it to speed up.

Now it barely exists.

Living like classic times...

All the real men who can hunt, kill, provide and protect families will survive.(Strong genes in these men)

Which means, the weak, uncoordinated, unathletic, unsmart men will die out alot faster (Bad genes).

Women who are more attractive *usually more voluptuous*(sign of fertility) will be chosen by men.

The thinner more fragile women would not be chosen (less fertile) which means they could die from giving birth.

Remember no hospitals...no anesthetics.

If we lived like that for a Generation, That generation, majoirty of the men will be Fit and strong. No couch potatoes and fatties. The women would be more prone to fertile traits (better assets) because of high fertility gene in blood.

We could then resume normal lives as we know it now, and wow people would be alot different for that one Generation.

Answer 13

if anything natural selection has come to a screeching halt.  theres nothign natural about some kid imitating jackass, getting seriously hurt, and then being kept alive and healed, living long enough to knock up some girl and pass his genes on to the next generation. whereas natural selection wouldve removed him from teh gene pool because he did stupid things likely to kill him. but when doctors intervene in situations like this, and keeping a lot of other people alive who would otherwise be dead...thats tampering with natural selection...and now the gene pool is a mix of the fittest and the complete opposite of them....

Answer 14

a radiation burst might do the trick. introduction of a foreign predator species could also speed up natural selection.