Modern human evolution

[iwant2know]

Let me start out by saying that I recognize these are rather controversial questions. By me asking these questions, please do not assume that I believe in/condone this sort of thinking. I am merely asking scientific questions.

 

Taking Herbert Spencer's theory regarding survival of the fittest and Charles Darwin's theory on natural selection, we see how animals select ideal mates through which to propagate their offspring. It follows that animals that are not ideal have a greater difficulty finding a mate. It is similar as well to how stronger specimens will commonly dominate territory, food chain, mates, etc....

 

Humans behave differently though. Humans take care of the weaker specimens and shape the environment to suit them (a.k.a. wheelchair ramps, hand rails, special education classes, treating physical and mental illness with medication, etc...).

 

For now let's please not have any political/moral/ethical replies. My questions are:

1. Are there any species other than humans that behave in this way? (assisting the weaker/less-ideal specimens, catering mating with less than ideal mates, etc...)

 

2. Are we ultimately dooming our own evolution by keeping unfavorable genetics in circulation? (Let us assume myself as "genetically unfavorable". I'm 5'8", 200 lbs, not athletic, and not exceptional at anything. I'm about as average as they come. My family has a history of breast cancer, heart disease, and Asperger syndrome).

Edited August 18, 2008 by iwant2know

[Sisyphus]

One way of looking at it is that we're not protecting the less fit, we're just changing the criteria for fitness. Basically, what is "genetically favorable" is, by definition, whatever helps you pass on your genes. So in modern society, a lot of things which formerly would be very disadvantageous, like poor eyesight, become much less important, because our "environment" is one in which glasses are not hard to come by. Evolution is still at work and we are still adapting to our environment, but our environment has changed and is still changing rapidly, so so too is the direction of our evolution.

 

I don't really think there's a close parallel in any other species, but there are rough parallels in pretty much any one. Other members of a species are almost always part of the environment, and so pretty much every species evolves in such a way that individuals take best advantage of their peers. The more social the animal, the more this happens, and humans have by far the most complex social patterns of all.

[CDarwin]

1. Are there any species other than humans that behave in this way? (assisting the weaker/less-ideal specimens, catering mating with less than ideal mates, etc...)

 

Well, much of it is a case of degree. Many social animals will exert some energy towards caring for the infirm and less able among them. A Vervet monkey might adopt an orphan of another mother, dolphins might protect an injured member of the pack. Humans take this social responsibility to a particular extreme, and are also very capable at it. Some of it is kin selection: it pays you genetically take care of your relatives because they share many of your genes. Some of it might be the the 'misfiring' of instincts suited to other purposes, like caring for other group member's children because of instincts evolved to cause you to take care of your own. Or, more controversially, it could be group selection. The theory goes that groups which have cooperative, altruistic members will do better than those with entirely Machiavellian members, thus altruistic behavior in a group setting is selected for.

 

Neanderthals, by the way, also almost certainly cared for their old, as is evidenced by extremely arthritic and toothless specimens like the old man from La-Chappelle aux Saints, who couldn't possibly have survived to the level of infirmity he achieved without a being supported by a benevolent group.

 

2. Are we ultimately dooming our own evolution by keeping unfavorable genetics in circulation? (Let us assume myself as "genetically unfavorable". I'm 5'8", 200 lbs, not athletic, and not exceptional at anything. I'm about as average as they come. My family has a history of breast cancer, heart disease, and Asperger syndrome).

 

Basically, you're favorable enough. If you weren't you would never reproduce. Evolution can't do any better than that. You can't say that 'dooms' us because obviously weren't doing just fine at propagating ourselves even with cancers and heart disease and genetic syndromes. Perhaps the genes that contribute (or cause) those things will become vital in the future. Or perhaps they will become so disadvantageous they will be scrubbed away by selection. Either way, there's no dooming.

[SkepticLance]

Are we dooming ourselves?

Short answer - no!

Evolution is a long winded slow process. It takes thousands to hundreds of thousands of years to effect major change. Yet human society is changing dramatically on a decade long scale.

 

One of those changes underway right now is an explosion of knowledge about genetics. Assuming humanity survives and progress continues, we can expect within 100 years that we will be eminently capable of genetic modification to remove harmful genes and incorporate useful genes into our offspring.

 

My prediction is that, within a few hundred years, every human will be descended from those who were so modified, and the new human species will be genetically very healthy.

 

Of course, choosing which genes are 'good' and which are 'bad' will be difficult. It will take the wisdom of a Solomon. Some are obvious. A gene for Parkinsons Disease will obviously be removed. What of Aspergers? Some 'sufferers' have made wonderful contributions to humanity. Should we remove that gene? I am glad it will not be my decision!

[Edtharan]

In environments that have low survival stresses, it gives the genomes of a species the ability explore configurations that otherwise would be less than needed to survive. This allows genetic drift and actually increases the survivability of the species.

 

Because a species that has undergone this kind of genetic drift has a much broader genetic base, when times get hard again, there will more likely be individuals that will be able to survive better than others and so the species will continue.

 

It does mean that there will be individuals that would not survive at all unless they were in such a low survival stress environment. However, it is because of these individuals that the genetic base is expanded.

 

In humans, it is our social systems and our tool use (technologies) that have provided this low survival stress environment. Through our technologies we have enabled individuals who would have otherwise have not survived to survive and this increases the genetic base of humanity.

 

If (or when) the survival pressure increases again, many of these will tragically not survive. But it is because of the variation that produced these in the first place that will mean that Humanity has a greater chance of survival.

 

This is the biggest argument against any form of eugenics. Under Eugenics, the society is imposing a very harsh survival stress. This eliminates the benefits of genetic drift and so reduces the societies overall ability to adapt to change.

 

Take for example the 2nd world war and the concept of the Arian race. This was a form of eugenics (if you didn't conform to this genetic standard then survival was made much harder, or you would be outright killed). Now imagine if this had continued, but then the Ozone layer was severly depleted (like we almost did).

 

This genotype has not got much protection against UV radiation from the sun. This genotype would then be badly adapted to the new environment (and therefore not genetically superior like the propaganda was trying to say).

 

Variation is genetically superior to a restricted genetic base.

 

It is elimination of variation that will spell the doom for humanity, not variation. Variation will be its saviour.

[iNow]

Are we dooming ourselves?

Short answer - no!

Evolution is a long winded slow process. It takes thousands to hundreds of thousands of years to effect major change.

 

Just to supplement this point, it's not always the case that evolution takes thousands to hundreds of thousands of years. That only applies in a stable environment. If the environment suddenly changes, you can have a sharp change in traits. Think in terms of the asteroid that hit circa 65mya. Practically immediately lots and lots of life died, but others quickly flourished and filled the newly available niches.

 

As a general rule, evolutionary changes do take a very long time to notice, but there are often events which quickly change the population which must be considered when making such comments and sharing ideas on the topic.

 

Also, bacteria can be seen evolving on incredibly short time scales... like hours... but we are talking about humans, so that's not quite as relevant.

[dichotomy]

If the environment suddenly changes, you can have a sharp change in traits. Think in terms of the asteroid that hit circa 65mya. Practically immediately lots and lots of life died, but others quickly flourished and filled the newly available niches.

 

That's an interesting point that makes me curious to why humans haven't (with the exception of microbes) forced a sharp change in traits on all the other species we are impacting on? Or, is agriculture and farming the example of forcing a sharp change in traits?

[iwant2know]

All very interesting theories/opinions. You've definitely given me things to think about.

 

When I referred to myself as "less than ideal" I was only doing that so as to "make fun of myself" like how a fat comedian would. Of course what I really am referring to is the eugenics experiments in WW2 (good catch Edtharan!!)

 

Of course "social darwinism" like that has happened many times in the past. It will be interesting for sociologists and psychologists to examine the new people group that is created once we finally have the first confirmed human clone.

[SkepticLance]

When we talk about natural evolutionary change, we need to specify what level of change. Homo sapiens has been on this planet about 200,000 years. That suggests that sufficient change to lead to a new species in a slow breeding species like our own normally takes hundreds of thousands of years. Simpler changes in gene frequency can take much shorter lengths of time. For example : the hemophilia gene is normally selected out of the population in about 10 generations. Damn thing keeps coming back through mutation!

[CDarwin]

All very interesting theories/opinions. You've definitely given me things to think about.

 

When I referred to myself as "less than ideal" I was only doing that so as to "make fun of myself" like how a fat comedian would. Of course what I really am referring to is the eugenics experiments in WW2 (good catch Edtharan!!)

 

Of course "social darwinism" like that has happened many times in the past. It will be interesting for sociologists and psychologists to examine the new people group that is created once we finally have the first confirmed human clone.

 

Eugenics and social Darwinism aren't strictly the same thing. Social Darwinism (I really wish they'd call it Spencerism or something and not besmirch poor Darwin, but I guess is name is more adjectivable) is the belief that the most fit societies, and most fit members of societies, will succeed over all others, and that this is natural and inevitable. Essentially, it's an argument against social action. Eugenics is quite the opposite. It's a very dramatic social action initiative.

[dichotomy]

That suggests that sufficient change to lead to a new species in a slow breeding species like our own normally takes hundreds of thousands of years.

 

Isn't the other accepted scenario that there is no significant change if a species is successful as it is?

[iNow]

Indeed.

[Sisyphus]

That's an interesting point that makes me curious to why humans haven't (with the exception of microbes) forced a sharp change in traits on all the other species we are impacting on? Or, is agriculture and farming the example of forcing a sharp change in traits?

 

We are. The "homo sapiens bomb" is causing all kinds of havoc in pretty much every ecosystem. But a "sharp change" is relative, when you consider the timeline of evolution. The dinosaurs wouldn't have noticed any change in their individual lifespans, either, and we are in the middle of a mass extinction event, comparable in many ways to the one 65mya. It's called the Holocene Extinction Event.

[dichotomy]

The dinosaurs were fantastic creatures; we are fantastic creatures, what branches off from Homo sapiens, after our self induced mass extinction event, would truly be even more fantastic. The mind boggles.

[Sisyphus]

The dinosaurs were fantastic creatures; we are fantastic creatures, what branches off from Homo sapiens, after our self induced mass extinction event, would truly be even more fantastic. The mind boggles.

 

Yeah. Maybe 100 million years from now, paleontologists from an intelligent species descended from today's cockroaches will be debating what killed off the mammals so suddenly...

[foodchain]

Actually modern homo sapien could survive a return to the wild I would think. If you mean via environmental ruin on global scale some post cataclysmic event type world, I would still think people to exist. I think what would occur though would be a stronger form of selection in various ways, such as obtaining water and food, being mass industry would have collapsed I think most basic facets of life for say America or Europe or most of the world would cease in some way.

 

So a huge genetic bottleneck? I think a worse case scenario is when pollution on a global scale brings about some kind of LD50 event on the human race, it’s a possible horror so I don’t think it should be ignored. Just going from conservation of energy alone common sense should dictate that our behavior would hold to some extent or some way an impact.

[Sisyphus]

I don't think you realistically make any prediction about what will ultimately happen to our species. We really have nothing to go on, since we are so different from anything else that has ever happened on Earth. In just a few dozen generations - basically an instant in geological time - we've spread to every ecosystem on Earth, multiplied our population a millionfold, altered our environment a hugely greater scale and variety than any other living thing, developed numerous ways to potentially destroy ourselves completely, created artificial intelligence, and learned the ability to intentionally alter the genetic code itself. And the rate of all this just keeps accelerating. Making hundred year predictions at this point is foolish. Making hundred million year predictions is beyond laughable.

[dichotomy]

Didn’t we (mammals) branch off from cold blooded reptilian type creatures? So it is plausible that a future species that dominates the earth, post Homosapiens, branches off from mammals, or specifically, Homosapiens? That species will find that they decended from warm blooded, large brained, know it alls, that really knew nothing afterall.

[Bicycle Seat]

There's only one problem here too, there is absolutely ZERO evidence that humans in fact evolved.

[YT2095]

there`s actually Plenty of evidence, again THINK before you post (that`s twice now).

[CaptainPanic]

Bicycle Seat, your strong arguments shock me. To people who realize that we've dug up bones of ancestors, and share many genes with other species, there was some kind of evolution...

 

I don't think you realistically make any prediction about what will ultimately happen to our species. We really have nothing to go on, since we are so different from anything else that has ever happened on Earth. In just a few dozen generations - basically an instant in geological time - we've spread to every ecosystem on Earth, multiplied our population a millionfold, altered our environment a hugely greater scale and variety than any other living thing, developed numerous ways to potentially destroy ourselves completely, created artificial intelligence, and learned the ability to intentionally alter the genetic code itself. And the rate of all this just keeps accelerating. Making hundred year predictions at this point is foolish. Making hundred million year predictions is beyond laughable.

 

I think the interesting thing is: humans will evolve, slowly, but humans are capable of changing the planet faster than its own genetics (unless we go into the lab, and make some GMO people, which I don't rule out).

[Ophiolite]

There's only one problem here too, there is absolutely ZERO evidence that humans in fact evolved.

I can understand BS that your religious convictions make it impossible for you accept the fact of evolution. I have no problem with that - I may feel sorry for you, but that is neither here nor there. However, if you plan to express your religious convictions on a science forum when those convictions run counter to current scientific thinking, then I advise you to choose a more circumspect approach.

 

Blatantly silly statements of the type above will simply cause you to be dismissed as a child and a fool. That makes your post the equivalent of a spoiled brat screaming in the corner of the room because it is not allowed to play with the antique vase: it is unpleasant for everyone involved and the child never gets its own way.

 

Specifically you could have said that some aspects of the vast body of evidence for evolution are ambiguous, controversial or contradictory. Stating there is no evidence simply reveals you as wholly uneducated to pass an opinion on the matter.

 

If you feel a compulsion to respond I trust you will do it via pm rather than contaminating these pages with yet another tranche of fourth rate creationist ranting.