Okay, let’s broaden the field. Which mammals are currently (thought to be) evolving into new species? Must be spoiled for choice there. Put it another way, which are those mammals that have a relatively high probability of belonging to that group (i.e. those (thought to be) evolving into new species)?
Re humans, since it’s a “fact” that we have many suboptimal characteristics (that’s a quote from talkorigins, by the way), then surely evolution ain’t gonna let a li’l technology get in the way of its - albeit purposeless - relentless march? Evolution’s not wimping out just when we have so many tools and instruments with which to observe and measure it? Objectively and all.
God made man
But he used the monkey to do it
Apes in the plan
We’re all here to prove it
I can walk like an ape
Talk like an ape
I can do what a monkey can do
God made man
But a monkey supplied the glue
Well, I’m no scientist but it would seem to me that all species are always under evolutionary pressure, just some to a greater degree than others. Those species that were under more drastic pressures would appear to be evolving quicker, because there might be more adverse situations that would select for a variety of things at once.
Likewise, a species with a greater base population would seem to evolve more slowly than one with a relatively small number of members; there might be more pressure on that species but it would take longer for a mutution to stablize and become an identifiable trait in the majority of the population, at which point it would probably be considered a new species anyway.
Besides, we can see the effects of evolution all around us, but we can’t see the process itself (except in specific conditions, such as in short lived species such as fruit flies), as it happens on a much longer time scale.
See, this is where we need Darwin’s Finch or Blake. However your question is not all that well formed. For example, when the environment changes those mammals with features that fit best into that changed environment will leave more descendants on average and the not-so-well fit characteristics will gradually fade out. Whether or not this is a new species, in the ordinary sense of not interbreeding, is impossible to tell because there aren’t any of the relatively less “fit” creatures around to test it. And this process takes thousands upon thousands of years because the not-so-well fit do leave some descendants for a considerable time.
One thing that can lead to the origination of a new species is geographic isolation for thousands of years in one enviroment that changes relative to that of the environment of those others of the original population.
Suboptimal doesn’t mean fatal. As Lynn Bodoni pointed out, people with what you refer to as ‘suboptimal’ traits are aided in reproducing by technology. And besides all humans have those suboptimal traits and so there is no genetically superior competition. The adaptation doesn’t have to be perfect and seldom is. All it has to be is good enough.
That’s an easy one. All of them. Give it ten million years or so, and you probably won’t see any of the same mammal species around as we have today. Some of them will be very similar to present-day species, of course, but if you brought them together with a time machine over ten million years, and they almost certainly wouldn’t be able to breed together.
But ten million years is an awfully long time to wait, and one species gradually shifting into another single very similar species is probably a bit boring. So how about a species splitting into two? That’ll happen whenever populations of a single species are separated from each other. For instance, there’s a species of squirrel that’s found on both sides of the Grand Canyon. They can’t cross the Canyon to get together on their own, but if you bring them together, they still can and will interbreed, so they’re considered the same species. But the two populations are already starting to show some different traits, and if you wait long enough, eventually they won’t be able to interbreed any more. Presto, two species from one.
We’re still evolving, too, and our decendants will eventually be some other species (if, of course, any of decendants are left at all). We can’t see this process directly, since it’s far too slow for human lifespans, or even the lifespans of human civilizations. And we don’t know what it’ll be, either. Maybe we’ll keep getting even smarter. Maybe we’ll split into two species, of happy, dumb Eloi and cunning Morlocks that eat them. Maybe robots will take over the caretaker function and we’ll all be Eloi. And maybe we’ll die off. There’s no way to know, in advance.
First of all, there is no purpose (or, as some would say, teleology) to evolution. All species, including H. sapiens sapiens, is constantly evolving. However, our lack of strong selective pressures due to our overarching ability to control our physical environment means that natural selection plays a much weaker role than it would in the wild. (This is just as true for New Guineans and ther primative peoples, who are all toolmakers, habitat builders, and so forth, as it is for “modern” societies.) If you follow the idea of the “meme” (as promoted by Richard Dawkins, Stephen Pinker, Daniel Dennett, et al) then our evolution has largely progressed from propogation of physical genes to conceptual memes or ideas that pass and mutate. We are still subject to genetic drift and mutation, of course, but selection pressure is largely negated by both our toolmaking ability and our compassion for those people (those with physical and mental disabilities) which would be normally weeded out, just as AKC breeds are “protected” against the effects of congenital defects that occur as a result of inbreeding.
Second; form, kind, species, family, whathaveyou: these are all concepts of taxinomy. Genes don’t recognize whether another creature is of the same “species” or “race” or “breed”; what they do recognize is that the genetic code of a potential reproductive partner is sufficiently compatible to create a viable offspring. The horse and burro, for instance, are considered different species because, even though they can interbreed, their offspring is sterile. Speciation generally occurs when populations are either geographically isolated, or have a pressure to conform to different nitches, i.e. the finches of Galapagos, which, despite living on the same small archipelago and sharing most of the same physical features are differentiated by their distinctive beaks, each species of which is configured for feeding on a particular insect. Ditto for fig wasps, et cetera. We (artificially) place these creatures in a group based upon some collection of characteristics and compatibility; in so recent a time as the past two centuries, though, some people classified the different human “races” to be different species (and idea that has fallen out of favor with more englightened people and never had any scientific justification from a biological standpoint.) Because of intermixing, and because speciation in such a complex species as higher mammals takes so long, we don’t currently see indications of what we might classify as speciation among modern man. However, the fossil record shows that many different branches hominids co-evolved and later became extinct or were destroyed or outcompeted by H. sapiens. The idea that modern man does not evolve at all is a falsehood.
There are indications that some neurological disorders are genetically based, and those which offer some benefits appear more prominently in populations where those benefits (and in which the detriments are less disadvantageous) allow marked success. For instance, the incidence of autistic spectrum disorders is significantly higher in Silicon Valley than in the general population, even accounting for the affluence and greater diagnositics. Greater mathematical and analyitical capability often accompanies some forms of ASD and Asperger’s Syndrome and is a natural advantage to someone working in the hard sciences and computer fields. While environmental selective pressures have largely been abated, pressures on intellect are stronger than ever, and in fields in which mathematical and logical assement ability is a premium (despite the decreased social abilities), the increased occurance of a disorder like ASD indicates that evolution is still continuing, just with different effects than would occur in nature.
While modern man may not clearly demonstrate evolution (or at least, the effects of natural selection) in the “normal” ways, it is obvious that the parasites that prey upon us do so with great regularity. As we develop vaccines and antibiotics, viruses and bacteria evolve into new strains that are able to circumvent or overcome those protections. Since we do our best to prevent infection and care for those afflicted, these have a smaller effect on the population than they otherwise would. However, evolution certainly played a big part in the Eurpoean conquest of the New World, with the native populace (evolved from a small population of Clovis or preClovis peoples) unable to fight of the infections carried by the European conquerors who came from a population who had already survived repeated waves of infection.
Oh, and Darwin’s Finch is still around, and will probably be along presently to correct/clarify/criticize/demolish what I’ve said above. I believe things are actually picking up for him a bit. (Good on ya, mate.)
Anyway, the idea that we aren’t evolving because we have tools, vaccines, and air conditioning fails to account for other pressures. For all we know, there may be an enormous selective pressure on typing speed. If you type less than 50 wpm, you better watch out! You just may not be able to attract a mate and may die after a lonely, bitter, non-reproductive existance while the 90 pound weakling with the 90 wpm typing skills lives the life of Flint.[sup]*[/sup]
Stranger
“Didn’t you use to have four women?”
“Well, at one time, sir, I had five. But that was getting to be a bit too much.”
This sounds highly speculative to my ears. Autistic spectrum disorders hardly represent a discrete, or agreed upon, cluster of entities. The word “disorder” itself, I would suggest, is indicative of the immensely speculative nature of that being discussed. Could in large part have a geratr deal to do with the way the kid is brought up - parents’ relationship key among those factors. You look for a certain answer though, and scientists down the years have proven themselves pretty adept at finding it.
Autism used to be considered the result of an emotionally frigid mother, with the attendant blame and attempts to “force” the patient to adapt to a more emotive state. The failures were manifest. It has since been demonstrated that autistic characteristics have a neurophysicial origin, i.e. that specific structures in the brain are less or differently developed than in the baseline population. Autistic children demonstrate their particular behavior very early in life; as early as three months they display rejection and emotional distance which distinguishes them from children with emotional trauma from abuse or neglect, and do so indepentantly of how they are reared.
While ASD does represent a wide range of behaviors which may or may not have a specific common origin (there is some debate as to whether Asperger’s Syndrome is similar to or co-indicated with autism, given that Aspies general show greater than normal intelligence whereas autistics are more generally subnormal in that area) there is a commonality in the inability of autistics/aspies to empathize and recognize subvocal and nonverbal communication. (This is also indicated with some forms of ADD and other neurological disorders, though perhaps due to different root causes.)
I picked this particular example because ASD and Asperger’s both show a high compound correlation with genetics, as opposed to congenital or post-natal environment. While physical selective pressures have been enfeebled by our ability to fit our environment to our strengths (rather than vice versa), we are even more strongly compelled by intellect than in nature. In the particular environment of Silicon Valley, where analytical ability is highly prized, a confluence of people who do have a high logical intellect has (apparently) lead to an increased incident of a condition which would otherwise normally be detrimental to reproduction. The ability to lift big weights, or bring down large game, et cetera, is less significant when we can buy or build tools to do the same, and has become more of a superficial accoutrement or a hobby than an indication of vital fitness.
The problem in looking for selective pressures in the behavior modern man is that so much of our behavior is based upon concepts learned in development rather than transmitted via genotypes. While genes offer a tendency toward this behavior or that, our attitudes are largely formed by experience. Only when the behaviors are dependant upon the extreme (as in logical reasoning ability) can we see the influence of genetics over cultural influence.
And, as others have pointed out, in higher vertebrates, evolution occurs on geological timescales; millions of years are indicated for distinct speciation. We could force selection in humans the same way we do in dogs and horses, via selective (in)breeding of small populations, and obtain near-term results, but naturally-induced evolution mostly occurs over longer timespans than even the most patient natural philosopher is able to endure.
What, that he’s doing okay, or that’s he’s going to string me up for any mistatements I’ve made?
Here’s a recent thread where he’s asking for dating advice…sooo, I guess he’s doing okay. Better 'n me in that regard, anyway. I hope things keep going well for him, even if he will beat me about the head with a hardcover, oversized print copy of Gould’s The Structure Of Evolutionary Theory.
Autism is a real, definable disorder. It can be defined in neurophysical examination (i.e. CAT and NMRI scans) as demonstrating different neurological characteristics compared to a baseline population. Unlike some disorders, it is actually relatively easy to diagnose with neurological testing. The notion that it is caused by poor parenting or other environmental influences was disabused in the Sixties.
As for attentional disorders (which are entirely distinct from autism and Asperger’s), the increased diagnosis of them is a combination of a greater awareness of the existance and a desire to pathologize “normal” attentional misbehavior. While ADD also demonstrates a genetic link, the diagnosis of it is less clear as the traits that are indicative of this “disorder” (i.e. forgetfulness, distractionablility, et cetera) meld continuously into the general population, whereas autistic spectrum traits are more distinct and therefore easier to diagnose.
You seem to be conflating two different conditions (ASD and attentional disorders), and avoiding a discussion as to whether ASD is genetically linked and whether it has a selection perogative in the modern, technological world.
I’m not entirely sure that one can make such strong claims about causation, or indeed about refuting such claims. Lots of guesswork involved. Who’s to know whether in the 2040s folk won’t be trashing, disabusing, refuting, whathaveyou, the findings and conclusions of the 2000s?
If you want to see speciation at work, before your very eyes, read up on ring species - these are observed instances where one species of animal can interbreed with its very similar (yet slightly different) neighbour, who can in turn interbreed with its very similar (yet slightly different) neighbour, who can in turn… etc - the point is that at all points of the chain, the adjacent animals are no more than slightly different from each other - so subtly that they look (and probably are) just varieties or subspecies. The very significant point though, is that the animals at opposite ends of the chain (which often encircle some geographic feature, or the globe itself) are so different that they cannot interbred - they really are different species.
Because each link in the chain can interbreed with the adjacent ones, they really are all one big gene pool - genetic information can (hypothetically) traverse the entire chain, it just can’t jump straight across the ends.
Are they one species, or more than one? This question is more an exploration of the limitations and application of our term ‘species’ - ring species are all one big happy gene pool - essentially just a very broad range of variety in a big group of animals that must share common ancestry. Add in an unfortunate catastrophe to wipe out the middle of the chain and you just have two separate species that will remain separate forerver.
Autism is not some minor techiness or sensitivity on the part of the child. It is a serious and blatantly apparent kind of mind-blindness which drastically affects the child’s ability to function in almost any social situation. I remember this article from New Scientist last year, but there are all kinds of experimental (PDF) correlations between the empathic response and the extremely “old” emotional parts of the brain (the limbic system, which even ancient lizards had). ‘Empathy blindness’ is very definitely a disorder: we might consider that our own response is “learned”, but when confronted with an autistic child (of those same loving, teaching parents such as our very own tomndebb, I believe) who simply can’t “get” empathy at all, we must surely look at the brain rather than the parents.
They will have to explain those same experimental results of the past 40 years which led us to discard those hypotheses in the 1960’s.
I believe things are actually picking up for him a bit. (Good on ya, mate.)
What exactly is your point, here?