Are humans evolving, or devolving, or both? (1 Viewer)

[bueno]

No, really big steps would be like the next generation being a different species.

A species has to start somewhere. There are examples of genetic fusion, though that isn't the correct term I'm trying to remember.

 

[bcdjr1]

It's not the strongest or smartest, it's what's best for the species.  Natural selection may be seen as positive or negative from parent to offspring, but, as a whole the evolution of the species is dependent on the total number of offspring and expected to evolve in such a way to have evolutionary success (the genes surviving).

Evolutionary success just means that they live long enough to bear offspring of their own. They don't have to be smarter or stronger or faster to be an evolutionary success. In this stage, it is less important for a human to have traits that would help them survive because other humans will help with that if it becomes a problem.

More, there are many offspring of those who are lacking in survival traits who are taken in by those who do have those traits by adopting them. Those adoptive parents, while in a better position socio-economically than their adopted child's biological parents, will often forego reproduction in order to raise their adopted children, if they even had the option to reproduce together in the first place.

More important now than being smarter or stronger or "better" is being fertile, finding a fertile partner, and being willing to reproduce. This is still natural selection and still evolution, even if the species were to become less capable than it has been in certain ways.

 

[Jayrod]

A species has to start somewhere. There are examples of genetic fusion, though that isn't the correct term I'm trying to remember.

"Mutation: it is the key to our evolution. It has enabled us to evolve from a single-celled organism into the dominant species on the planet. This process is slow, and normally taking thousands and thousands of years. But every few hundred millennia, evolution leaps forward."

 

[bcdjr1]

A species has to start somewhere. There are examples of genetic fusion, though that isn't the correct term I'm trying to remember.

Yeah, but it's not going to be from one generation to the next. There will be transitional generations.

 

[NCCommish]

Humans are still evolving. We have picked up many genetic variations over the last 2k years which is a blink of the eye in evolutionary terms.
 

Humans are still evolving—and we can watch it happen

Many people think evolution requires thousands or millions of years, but biologists know it can happen fast. Now, thanks to the genomic revolution, researchers can actually track the population-level genetic shifts that mark evolution in action—and they’re doing this in humans. Two studies presented at the Biology of Genomes meeting here last week show how our genomes have changed over centuries or decades, charting how since Roman times the British have evolved to be taller and fairer, and how just in the last generation the effect of a gene that favors cigarette smoking has dwindled in some groups.

“Being able to look at selection in action is exciting,” says Molly Przeworski, an evolutionary biologist at Columbia University. The studies show how the human genome quickly responds to new conditions in subtle but meaningful ways, she says. “It’s a game-changer in terms of understanding evolution.”

Evolutionary biologists have long concentrated on the role of new mutations in generating new traits. But once a new mutation has arisen, it must spread through a population. Every person carries two copies of each gene, but the copies can vary slightly within and between individuals. Mutations in one copy might increase height; those in another copy, or allele, might decrease it. If changing conditions favor, say, tallness, then tall people will have more offspring, and more copies of variants that code for tallness will circulate in the population.               

With the help of giant genomic data sets, scientists can now track these evolutionary shifts in allele frequencies over short timescales. Jonathan Pritchard of Stanford University in Palo Alto, California, and his postdoc Yair Field did so by counting unique single-base changes, which are found in every genome. Such rare individual changes, or singletons, are likely recent, because they haven’t had time to spread through the population. Because alleles carry neighboring DNA with them as they circulate, the number of singletons on nearby DNA can be used as a rough molecular clock, indicating how quickly that allele has changed in frequency.  

Pritchard’s team analyzed 3000 genomes collected as part of the UK10K sequencing project in the United Kingdom. For each allele of interest in each genome, Field calculated a “singleton density score” based on the density of nearby single, unique mutations. The more intense the selection on an allele, the faster it spreads, and the less time there is for singletons to accumulate near it. The approach can reveal selection over the past 100 generations, or about 2000 years.

Stanford graduate students Natalie Telis and Evan Boyle and postdoc Ziyue Gao found relatively few singletons near alleles that confer lactose tolerance—a trait that enables adults to digest milk—and that code for particular immune system receptors. Among the British, these alleles have evidently been highly selected and have spread rapidly. The team also found fewer singletons near alleles for blond hair and blue eyes, indicating that these traits, too, have rapidly spread over the past 2000 years, Field reported in his talk and on 7 May in the preprint server bioRxiv.org. One evolutionary driver may have been Britain’s gloomy skies: Genes for fair hair also cause lighter skin color, which allows the body to make more vitamin D in conditions of scarce sunlight. Or sexual selection could have been at work, driven by a preference for blond mates.

Other researchers praise the new technique. “This approach seems to allow much more subtle and much more common signals of selection to be detected,” says evolutionary geneticist Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.

In a sign of the method’s power, Pritchard’s team also detected selection in traits controlled not by a single gene, but by tiny changes in hundreds of genes. Among them are height, head circumference in infants, and hip size in females—crucial for giving birth to those infants. By looking at the density of singletons flanking more than 4 million DNA differences, Pritchard’s team discovered that selection for all three traits occurred across the genome in recent millennia.

Joseph Pickrell, an evolutionary geneticist at New York Genome Center in New York City, has used a different strategy to put selection under an even keener microscope, detecting signs of evolution on the scale of a human lifetime. He and Przeworski took a close look at the genomes of 60,000 people of European ancestry who had been genotyped by Kaiser Permanente in Northern California, and 150,000 people from a massive U.K. sequencing effort called the UK Biobank. They wanted to know whether genetic variants change frequency across individuals of different ages, revealing selection at work within a generation or two. The biobank included relatively few old people, but it did have information about participants’ parents, so the team also looked for connections between parental death and allele frequencies in their children.

In the parents’ generation, for example, the researchers saw a correlation between early death in men and the presence in their children (and therefore presumably in the parents) of a nicotine receptor allele that makes it harder to quit smoking. Many of the men who died young had reached adulthood in the United Kingdom in the 1950s, a time when many British men had a pack-a-day habit. In contrast, the allele’s frequency in women and in people from Northern California did not vary with age, presumably because fewer in these groups smoked heavily and the allele did not affect their survival. As smoking habits have changed, the pressure to weed out the allele has ceased, and its frequency is unchanged in younger men, Pickrell explains. “My guess is we are going to discover a lot of these gene-by-environment effects,” Przeworski says.  

Indeed, Pickrell’s team detected other shifts. A set of gene variants associated with late-onset menstruation was more common in longer-lived women, suggesting it might help delay death. Pickrell also reported that the frequency of the ApoE4 allele, which is associated with Alzheimer’s disease, drops in older people because carriers died early. “We can detect selection on the shortest timeframe possible, an individual’s life span,” he says.

Signs of selection on short timescales will always be prey to statistical fluctuations. But together the two projects “point to the power of large studies to understand what factors determine survival and reproduction in humans in present-day societies,” Pääbo says. 

Sciencemag.org

 

[tonydead]

Evolutionary success just means that they live long enough to bear offspring of their own. They don't have to be smarter or stronger or faster to be an evolutionary success. In this stage, it is less important for a human to have traits that would help them survive because other humans will help with that if it becomes a problem.

More, there are many offspring of those who are lacking in survival traits who are taken in by those who do have those traits by adopting them. Those adoptive parents, while in a better position socio-economically than their adopted child's biological parents, will often forego reproduction in order to raise their adopted children, if they even had the option to reproduce together in the first place.

More important now than being smarter or stronger or "better" is being fertile, finding a fertile partner, and being willing to reproduce. This is still natural selection and still evolution, even if the species were to become less capable than it has been in certain ways.

I don't think that's true.  Evolution has everything to do with the species.  Natural Selection does not equal Evolution, natural selection is a part of evolution.  

 

[matttyl]

Ants have been evolving in an environment that includes anthills for a long time, to the point that they might be less likely to survive in the absence of one than whatever their most recent non-colony-insect ancestor was. Since anthills are built by ants, is this an example of them evolving "outside of nature"?

Not really.  It's an example of a family or colony making a habitat for itself.  Humans were doing the same way back in the day when we were living in caves - or any number of burrowing creatures.

 

[CBusAlex]

Not really.  It's an example of a family or colony making a habitat for itself.  Humans were doing the same way back in the day when we were living in caves - or any number of burrowing creatures.

So how is it any different when humans make habitats that include things like hospitals? Is there some level of complexity an anthill could reach that would make it no longer a part of "nature"?

 

[bueno]

Yeah, but it's not going to be from one generation to the next. There will be transitional generations.

Sometimes yes, sometimes maybe not. We have yet to see the creation of an advances species (think vertebrates here, not single-celled organisms). It would be neat to see.

 

[matttyl]

So how is it any different when humans make habitats that include things like hospitals? Is there some level of complexity an anthill could reach that would make it no longer a part of "nature"?

As soon as they install a bed, bath and beyond?

 

[tonydead]

Sometimes yes, sometimes maybe not. We have yet to see the creation of an advances species (think vertebrates here, not single-celled organisms). It would be neat to see.

Endler's Guppy Fish is one of the "quickest" examples of evolution that I'm aware of that we've observed.  I think the development of a vertebrae is a much, much slower evolution process.

 

[Maurile Tremblay]

So how is it any different when humans make habitats that include things like hospitals? Is there some level of complexity an anthill could reach that would make it no longer a part of "nature"?



 

As soon as they install a bed, bath and beyond?




 

Bed, Baths, and Beyond are natural. To make something supernatural, I think the ants would need to install a Mosque or a Temple or something, at the very least.

 

[cstu]

Social status doesn't seem to be very well correlated with any particular genetic traits. A family's members very commonly move significantly up or down the social ladder within a few generations.

My understanding of the brain is that there is very little difference between normal brains of human beings.  What we call 'smart' and 'dumb' is primarily a result of environmental factors rather than genetic ones.  A so-called 'dumb' person can speak, read and write, and analyze complex ideas (if they wish to).  Half the population has an IQ score between 90 and 110 (normal intelligence) and I think if you were stuck in a room with only people with 90-110 IQ scores you would be hard pressed to determine which is which.  

 

[cstu]

Sometimes yes, sometimes maybe not. We have yet to see the creation of an advances species (think vertebrates here, not single-celled organisms). It would be neat to see.

Italian wall lizard

Researchers found that the lizards developed cecal valves—muscles between the large and small intestine—that slowed down food digestion in fermenting chambers, which allowed their bodies to process the vegetation's cellulose into volatile fatty acids.

"They evolved an expanded gut to allow them to process these leaves," Irschick said, adding it was something that had not been documented before. "This was a brand-new structure."

Along with the ability to digest plants came the ability to bite harder, powered by a head that had grown longer and wider.

 

[bcdjr1]

I don't think that's true.  Evolution has everything to do with the species.  Natural Selection does not equal Evolution, natural selection is a part of evolution.  

Evolution is the process of change. Natural selection is when offspring is produced without an outside intelligence dictating the means of its production. For example, eugenics is an example of unnatural selection.

Regardless if the species evolves via natural or unnatural selection, the result - unless it's extinction - is an evolutionary success. Eugenics has been used by humans to create dog breeds, which is an example of successful evolution through unnatural selection.

 

[James Daulton]

So how long until the mutants with their mutant powers appear?  I want to make sure I'm on the ground floor for that one.

 

[Cold Dead Hands]

So how long until the mutants with their mutant powers appear?  I want to make sure I'm on the ground floor for that one.

Mutants are here. I apparently have the mutant ability to negate my wife's sex drive.

 

[lod001]

Definitely both. However it's at least a 100 to one ratio. For every one of us evolving there are 100 or more devolving and creating many more of their kind as well. Devolvers can pump out as many future devolvers as they want. Evolvers cannot afford to. This planet will resemble an outhouse eventually. Actually the bottom of the crapper in an outhouse.

 

[James Daulton]

Mutants are here. I apparently have the mutant ability to negate my wife's sex drive.

Well, it's a start.

 

[Maurile Tremblay]

Definitely both. However it's at least a 100 to one ratio. For every one of us evolving there are 100 or more devolving and creating many more of their kind as well. Devolvers can pump out as many future devolvers as they want. Evolvers cannot afford to. This planet will resemble an outhouse eventually. Actually the bottom of the crapper in an outhouse.




 

Individuals do not evolve or devolve.

 

[tonydead]

Evolution is the process of change. Natural selection is when offspring is produced without an outside intelligence dictating the means of its production. For example, eugenics is an example of unnatural selection.

Regardless if the species evolves via natural or unnatural selection, the result - unless it's extinction - is an evolutionary success. Eugenics has been used by humans to create dog breeds, which is an example of successful evolution through unnatural selection.

Do you have an example of extinction that happened exclusively by evolution?   I believe evolution generally if not always works to preserve the gene.  Link

(a) For geographically widespread species, extinction is likely only if the killing stress is one so rare as to be beyond the experience of the species, and thus outside the reach of natural selection. (ii) The largest mass extinctions produce major restructuring of the biosphere wherein some successful groups are eliminated, allowing previously minor groups to expand and diversify. (iii) Except for a few cases, there is little evidence that extinction is selective in the positive sense argued by Darwin. It has generally been impossible to predict, before the fact, which species will be victims of an extinction event.

 

[cstu]

Do you have an example of extinction that happened exclusively by evolution?   I believe evolution generally if not always works to preserve the gene.

Evolution is a result not an active process.  No genes are being preserved, only the genes of those who reproduce get passed on. 

If nothing changes in an environment (food, weather, competitors) then there's no reason why the organisms most adapted to that environment would go extinct.  However, in the real world the the environment is constantly changing.

 

[tonydead]

I think this is what your are referring to:  Link.  Even the examples listed like the depleted food source is reliant on environmental factors.  As the wiki states, "empirically establishing that an extinction event was unambiguously caused by the process of adaptation is not a trivial task.", so I don't think we can state this as fact.  I think Darwin's extinction is one of his theories that isn't holding up to recent evolutionary biology.  Maybe Maurile can chime in.

 

[ChainsawU]

I'm a huge fan of nature shows like "Life" and "Earth."

A lot of people aren't. So I say good for you, no matter if you were "born early" or whatever. Simply enjoying those shows, knowing, and respecting the fact that our species has made it millions of years to get to this point should inspire you want to be a better person, physically and mentally. Personally I'm just happy to have food and clean water, and that I never have to outrun a cheetah. Knowing and being thankful of where we come from is a beautiful thing and it would be a shame to waste it on being mediocre or not trying your best at everything. I think that survival of the fittest can mean not only competing against others, but competing against yourself as well.

 

[tonydead]

Evolution is a result not an active process.  No genes are being preserved, only the genes of those who reproduce get passed on. 

If nothing changes in an environment (food, weather, competitors) then there's no reason why the organisms most adapted to that environment would go extinct.  However, in the real world the the environment is constantly changing.

Agree, its the genes that get passed on that I'm referring to.   Maybe species is a better word.  

 

[Maurile Tremblay]

Do you have an example of extinction that happened exclusively by evolution?   I believe evolution generally if not always works to preserve the gene.  Link




 

I'd say that all extinctions are examples of evolution, in a sense. Evolution is the change in allele frequencies over time. Extinction reduces the frequency of every allele in a species to zero, which is a change.

Natural selection normally works by promoting some genes at the expense of others, weeding the latter genes out. In an extinction event, all the genes get weeded out, which is kind of extreme, but that's what generally ends up happening to more than 99% of all species, eventually.

 

[cstu]

I'd say that all extinctions are examples of evolution, in a sense. Evolution is the change in allele frequencies over time. Extinction reduces the frequency of every allele in a species to zero, which is a change.

Natural selection normally works by promoting some genes at the expense of others, weeding the latter genes out. In an extinction event, all the genes get weeded out, which is kind of extreme, but that's what generally ends up happening to more than 99% of all species, eventually.

When you put it that way...

 

[bcdjr1]

Do you have an example of extinction that happened exclusively by evolution?   I believe evolution generally if not always works to preserve the gene.  Link

I think you could also argue that certain hybrids such as ligers, tigons, mules, etc. are examples of evolution leading to extinction. These hybrids are born sterile and therefore unable to procreate.

 

[tonydead]

I think you could also argue that certain hybrids such as ligers, tigons, mules, etc. are examples of evolution leading to extinction. These hybrids are born sterile and therefore unable to procreate.

I don't think any of those are considered species in their own right because they don't territoriality overlap and mate if they are not forced to under captivity.  I don't think most biologist count forced breeding of traits as natural selection because, well, it didn't happen naturally.  The bulldog for example.  And your claim that all those hybrids are sterile is false.  If they were to naturally breed and eventually have cases that weren't sterile (like they have had in captivity) I think that would be an example of evolution denying extinction.  

 

[bueno]

Evolution is the process of change. Natural selection is when offspring is produced without an outside intelligence dictating the means of its production. For example, eugenics is an example of unnatural selection.

Regardless if the species evolves via natural or unnatural selection, the result - unless it's extinction - is an evolutionary success. Eugenics has been used by humans to create dog breeds, which is an example of successful evolution through unnatural selection.

But they are breeds, not separate species. We have yet to observe the creation of a new species of vertebrate.

 

[bueno]

A lot of people aren't. So I say good for you, no matter if you were "born early" or whatever. Simply enjoying those shows, knowing, and respecting the fact that our species has made it millions of years to get to this point should inspire you want to be a better person, physically and mentally. Personally I'm just happy to have food and clean water, and that I never have to outrun a cheetah. Knowing and being thankful of where we come from is a beautiful thing and it would be a shame to waste it on being mediocre or not trying your best at everything. I think that survival of the fittest can mean not only competing against others, but competing against yourself as well.

Me, I get pissed when they over-simplify.

 

[cstu]

We have yet to observe the creation of a new species of vertebrate.

Did you miss my link?

 

[bueno]

Did you miss my link?

I saw it, and it is an exciting development, but technically this may not be the creation of a totally new species.

 

[lod001]

Individuals do not evolve or devolve.

You missed the point.

 

[TripItUp]

I'd say that all extinctions are examples of evolution, in a sense. Evolution is the change in allele frequencies over time. Extinction reduces the frequency of every allele in a species to zero, which is a change.

Natural selection normally works by promoting some genes at the expense of others, weeding the latter genes out. In an extinction event, all the genes get weeded out, which is kind of extreme, but that's what generally ends up happening to more than 99% of all species, eventually.

don't forget mutation!