Do you think we have permanently disrupted the evolutionary path of humans?

Question

With our advances in medical science and our ability to alter the environment to suit us?

Answer 1

That's a good question, but it has been asked before ...

Pretty much everyone knows that Charles Darwin first formulated the idea that evolution of species is driven by natural selection acting on genetically variable populations. What a lot of people may not know is that there was a second scientist who published the same idea at the same time: Alfred Russel Wallace. To those in the game, he is the 'co-discoverer of evolution'.

Wallace was also the first person to formulate the idea that the human mind has changed our relationship to natural selection. He published a paper about this in 1864! So these thoughts have been around almost since natural selection was first put forward.

At what point did the human mind start to rewrite how we might evolve? I think it hasn't happened with technology and medicine, but that it happened long ago when a hominid or ape noticed another using a tool and copied that action. As soon as one of our ancestors used fire to chase away a threatening animal or knocked fruit off a tree using a stick, and another one learned to do it, our ancestors were already using their thinking ability to develop solutions to problems that previously could only have been solved by evolving a modified body part.

I hope that makes sense: to reach high fruit, a giraffe needed a long neck, an elephant needed a trunk, or a bat used wings. But our ancestors could get the fruit without waiting for natural selection to change our bodies to do it. And so over the next few million years we became slower and weaker relative to our closest primate relatives, but we became phenomenal designers and users of tools - including the ultimate tool, language.

In a sense, our ancestors were freed from the bounds of natural selection on our bodies, but at the same time selection on our brains/minds honed them into true marvels of nature: there are a lot of brains around, but none are even close to human intellectual capacity.

Wallace emphasized that we are a species "in whom mind was of vastly greater importance than bodily structure."*

Since this transition of the relationship of our minds and bodies to natural selection started long before Homo sapiens arose, living humans are largely the product of this altered evolution. There is no need to redefine evolution for the brave new world of medicine, it was already redefined millions of years ago ... and since we are here, clearly it hasn't been disabled or inhibited.

In fact, I would suggest that since our minds (by ideas and tools) are now able to preserve gene variations that previously would have been selected against by nature, we are increasing our genetic variation and increasing our ability to evolve - remember that evolution works by selection on a genetically variable population and we are becoming more variable.

Some other things to consider:
I suppose that one thing you are asking about is whether disease causing mutations are somehow going to devolve humans. I think not, in part because such mutations will remain rare compared to the number of people around, and so genetic disease incidence will remain low. But also:
People will and do choose not to have children who will be born with severe diseases - this opportunity to choose arises by our technology as well. i.e. Jews in Canada were offered testing for Tay-Sachs heterozygosity in high school and the knowledge that one was a carrier influenced mating such that the incidence of this terrible disease fell tremendously.

Also: humans are still under selection at lots of genes. Recent work has identified many areas of the genome that have been selected for recently. They include, for example, areas involved in immune system function = we are still susceptible to many, many diseases, and that puts pressure on our genes to respond.

Lastly, what might we evolve into? As some of the other answers to your question noted, we don't know where evolution is going = it isn't planned. And so, we, or at least I, can't predict what sorts of traits might be useful in the environment of the future ... with one exception: I think the genes that influence our communication abilities are under a lot of selective pressure. Arguably, Homo sapiens' most distinctive trait is her/his ability to use language, and it is definitely a skill that is needed to survive and reproduce under most circumstances. We also need to be able to judge others emotional and psychological states as part of our communication abilities. I think in a fast paced and crowded world, these abilities will only become more crucial ... hence, selection will continue to act on humans to sharpen these traits further.

Interestingly, a story was reported in the past few days that female chimpanzees have been observed hunting with spears. It is easy to see that this changes the equations for chimpanzee evolution, at least in the populations where this occurs: instead of being selected to be stronger and more vicious, it might be imagined that they are going to be selected to be more dextrous and better at planning ahead. So ... is this evidence that chimpanzees are starting to 'disrupt' evolution? Or is it evidence that they are smart enough that they are starting to free themselves from selection on their bodies just as we have? Interesting, no?

Answer 2

The word 'disrupted' implies a lot of things that I'm not sure really apply to the question at hand.

ANY change to the environment, bodies, behaviour, nutrition, and just about anything else has the potential to affect evolutionary outcomes. NO change is likely to ever stop the evolutionary process altogether.

The availability of sweaters means that temperature isn't as much of a condition for survival. Antibiotics remove some bacteria as threats. Elimination of standing water can also eliminate disease-spreading insects. So yes, all these things could potentially have an impact.

But consider: people still die. As long as people die, some are likely to have advantages that others don't, and thereby possibly cause some kind of long-term evolutionary effect. There are people, for example, who are completely immune to HIV. Some people are much more prone to cancer than others. Some are sensitive to latex, some to aspartame, and some to cigarette smoke. All these things might potentially affect survival and reproduction.

So don't worry about evolution stopping any time soon. Different changes may predominate than if we all still lived in caves, but that hardly means they aren't there at all!

Answer 3

I don't think the medical science thing is as big an issue as the population dynamics and human culture. I also don't think we so much alter the environment to suit us as we alter ourselves to suit our environment and shield us from natural selection.
The theory of evo states that unfit individuals will be selected against thus leaving more fit individuals. That is confounded by eye glasses, winter jackets, insulin, and emotions such as pity and sympathy and generosity

Furthermore, with airflights all over the world there is no possibility for populations to become/remain isolated and thus genetically dissimilar than the rest of humanity.

Think of wars. Whats the first thing you have to pass to get in the army. A physical. Thus the more fit, physically anyway, individuals are at higher risk of leaving the population.

Answer 4

This question presumes that humans were on some evolutionary "path", and it is possible to "disrupt" that path ...i.e. knock humans "off" the path they were otherwise following.

It is very important to understand that evolution is not a predetermined "path."

Howeve, that said, yes it is true that humans are certainly *affecting* their own evolution in ways that no other animal has ever done. We can directly control many aspects of our environment (what diseases eliminate individuals, what mutations can survive, what mutations are encouraged), etc.

Answer 5

there is not any "classic" evolutionary direction. Mammals do seem to have progressed to have extra effective brains, yet that is by using fact of evolving extra effective bodies. super bodies might desire extra foodstuff yet are harder to prey upon. A lion could be waiting to seize a small antelope yet for a common satisfaction might could seize 5-6, mutually as an entire giraffe will feed an entire satisfaction yet will take the whole satisfaction to tug down, and the percentages against everybody giraffe being hunted are extra advantageous. Hominids might have progressed intelligence for something different than how we use it in the present day; for example, understanding complicated pathways for feeding websites or for complicated social interactions. in basic terms as giraffes progressed an prolonged neck "for" some specific purpose, whether it incredibly is used for accomplishing tall tree tops' leaves, looking forward to enemies an prolonged way off, and neck-wrestling for herd dominance besides.

Answer 6

Only in the sense that we've stopped the biological evolution of humans.

If you look at human beings, we have the technology to assure that all humans (or at least a random sampling) reach adult reproductive age, regardless of fitness (those 6 billion people out there must be proof of that). There are no differences in REPRODUCTIVE FITNESS, hence there is no natural selection in human populations, hence there is no evolution in human populations.

Human technologies may evolve, but humans as a species have stopped undergoing biological evolution long ago. And no, it's not going on at a slow rate, and no, evolution does not happen continuously.

However, I have to agree with Sauce, in that there is no path to be disrupted. Evolution moves without direction.

Answer 7

No.Just the opposite.
It isn't the fact we are living longer, but our enormous gene pool that works for us. Today we intermarry with races that was not accepted just back in the sixties. This helps even more to enlarge the pool.
The fact that we are not a small group that must interbreed iliminates a lot of gene changes in reverse.
If the hman race got down to such a small group that we had to breed with sisters and cousins, there would be a degeneration of gains up the evolutionary ladder.

Answer 8

Yes, but for the worse - humans aren't being selected properly - we're experiencing genetic drift and people with low intelligence are breeding more rapidly than more intelligent humans - therefore stupidity will become a more common feature in the genepool of humanity.

Answer 9

Most definately. The vaccines that have been around lately are pumping our kids with animal dna, thus forever changing the human genome. Turning our youth into creatures of habit, survival and instinct, not with human conscience and compassion.

Answer 10

Yes, without a doubt.