This standard creationist question is usually answered as shown here - the current set of monkeys are not our ancestors. However it shows a deeper lack of understanding of how evolution works, since it seems to state that monkeys go to sleep one night and wake up as humans, or, at best, a whole population of monkeys suddenly have human babies. That’s why I usually ask a creationist who shows up what he thinks evolution actually says. They seldom answer.
I kinda hate to go off topic here, as I’m sure it’s not commonplace in GD, but I have to say that I was impressed by the responses here. Factual responses are almost always accurate and complete here, but it’s the other responses that flavor a thread IMO.
I keep away from GD like it’s the plague, mostly because I don’t like arguing, and opinions are not subject to any reasonable form of objectivity, by definition I suppose.
Long story short, my faith in the 'Dope has been renewed, and in the least likely of forums for me to even be reading, let alone posting in. LLTD
You might want to read up on Darwin’s finches. A variety of species developed, each adapted for the particular type of food they ate and the environment of the islands on which they lived. Look at giraffes: if every animal ate leaves from the tops of trees there would be no advantage. Evolution through natural selection has resulted in species adapted for all sorts of food: wood, grass, insects, meat, fruit, nectar, dung, krill, etc. Likewise species have developed for all sorts of environments: below ground, on the ground, above the ground, in our gut, in fresh water, in salt water, near deep ocean vents, in the arctic, and in the tropics. Occupying a new niche is as good as occupying your current one in a better way.
So to make a long story short, some of our ancestors stayed in their ecological niches while others evolved to occupy new ones.
If environmental change is responsible for evolution within the great apes, then how do you explain a human population that remains in the same environment as chimps.
First off, they don’t *remain *in the same environment, they have secondarily re-entered that environment. Just as dolphins don’t remain in the same environment as fish. In both cases the ancestors left that environment, gained novel traits and then re-entered the ancestral environment, able to exploit tin novel ways because of the novel traits.
Secondly no humans are capable of living in tropical rainforests full time. If we tried we would starve to death on short order. Which rather proves that our current form is unsuitable to survival in that environment.
Chimps don’t taste good.
I do the same thing. I come to the dope with things that I want to learn more about, and I KNOW I will get certain responses that will either try to make me feel stupid, or will question the sincerity of my question. And I don’t let it stop me. I let it roll off and focus on the dopers that are actually willing to help.
ETA: no offense to DanBlather, I see he is helping you. I meant, in general.
Pygmies don’t ‘remain’. Humans evolved over millions of years in one area of East Africa, then spread across Africa and eventually across the globe. One of our defining characteristics as a species is our adaptability, something that none of our ape relatives share (every one of them needs a specific habitat, and every one of them is endagered).
Like every other human group who doesn’t use agriculture, the most valuable item in the Pygmy diet is the animals they hunt, using their large brains and weapon-making ability. This is one reason for our ability to survive in many different enviroments - there was always game to hunt. We are also excellent travelers on the ground compared to every other primate.
In contrast, the staple of the chimpanzee diet is certain leaves and fruit, they spend their lives largely in trees, and their bodies are well-suited for it (long toes and arms, flat teeth for grinding tough vegetation, small brains that do not burn so much energy that fat in the diet is essential). Since they are not physically suited for traveling across treeless distances, they are becoming trapped in smaller and smaller islands of forest…
Your question makes about as much sense as wanting an evolutionary explanation for Swedish farmers or Brazilian rain forest dwellers.
The environment does not need to change for evolution to occur. A mutation might make an individual able to exploit something about the current environment in a better way. For example, an animal might develop better claws that allows it to climb trees. If those traits are passed on, then that group of individuals may become isolated from the rest of the species because they spend more time in trees. The isolation reinforces the development of the trait because it will not be diluted by individuals that lack the mutation. Eventually the two groups may differ enough that they could be classified as different species. This is essentially what Darwin’s finches showed.
Other sorts of isolation can make specieazation happen more quickly. A previous poster has given the example of a landslide separating a population of animals into two groups that will develop separately. Even if the environment remains the same in both areas, eventually genetic drift might result in them having different traits. Those traits may be different enough that the two groups will not or can not interbreed.
Remember, mutations do not occur as a result of a change in the environment, they occur at a constant rate. A change in the environment may make certain mutations more advantageous then they otherwise would be, but an environmental change is not necessary.
Think of it like this: the Protestants split off from the mainline church, but both groups remained. The environmental change that may have reinforced the schism is the printed bible that allowed more people the ability to interpret it for themselves rather than rely on clergy to read from an expensive hand-copied bible. Maybe that is why Lutheranism developed in Germany, where Gutenberg first printed bibles just 30 years before Luther’s birth. The idea that people can read the bible for themselves was not unique, but it would not have flourished without access to bibles.
Consider each species as a person in a job, with the job being the niche in the environment that the species occupies.
Even if every person wants to be President, there is only one person who can hold that job at any time. The other jobs in the country need to be filled as well.
(To the OP – why would you think that apes and monkeys would NOT be around, just because there are humans around? Do you think they should have all turned into humans, or do you think we should have just out-competed them and they died off?
If you think they should have become human by now, remember that evolution has no long-term goal. Evolution is just the result of organisms competing to reproduce enough that their offspring survive to breed in their own right. The differences in individual organisms that allow any one of them to do just a little better today and here are the source of variation, not any projected aproach to some ideal.)
I actually think this is an oversimplification that confuses a lot of people who aren’t familiar with modern evolutionary theory (‘punctuated equilibrium’ which posits large amounts of change in short bursts of time doesn’t have a lot of believers anymore).
The mutations that occur during evolution are incredibly rare and very minor. It’s not a matter of one animal within a population developing an extreme mutation (such as a totally different claw form), and becoming reproductively successful so that more and more animals within the population share this trait. It’s a matter of tiny, tiny, tiny degrees usually over many millions of years.
Yes, you are right, I was way over simplifying.
I’d like to know more about the current thought on punctuated equilibrium. I went to Antioch College a few years after Gould and had some of the same professors, so I am particularly interested. My understanding of punctuated equilibrium was that changes to the environment could cause an otherwise stable population to more quickly acquire new traits since there was more “pressure” put on them. Is this no longer accepted? I thought the fossil record shows large changes happening relatively quickly (still a very long time, however) after long periods of stability.
One of Gould’s geology professors would have his class read Velikovsky (yes he knew it was bunk) so that we’d understand that the catastrophism/gradualism debate is not an either/or thing. We have gradual processes that create great changes and occasional events like large scale volcanism, the Missoula floods, meteorite strikes, and others that create sudden changes. I always wondered if Gould was influenced by that to come up with PE.
ETA: There are some mutations that can cause large changes however. For example a mutation might cause a segmented animal like a millipede to have more or less segments. That would look like a big change, even though it is a simple change in the genetic coding.
Punctuated equilibrium is not “large amounts of change in short bursts of time”. It is an explanation for the appearance of the fossil record - fossil species appear “suddenly” in the record and remain stable for much of their duration in the record. The explanation for this is that speciation occurs within “peripheral isolates” - small portions of the main population which are separated from the parent population and diverge rapidly. Because the new population is small, it is unlikely to fossilize. As a result, representatives of that population only appears in the fossil record once the population has increased sufficiently in size for an already-rare process to occur.
What you are describing is “saltationisim”, which, indeed, is not in vogue amongst evolutionary biologists these days.
Again, it’s not about anything happening more rapidly than at other times. What it essentially boils down to is that speciation is a process that is likely more rapid than prior workers had accounted for. Darwin’s “slow and steady” was taken as gospel, meaning that gaps in the fossil record were attributed solely to poor preservation. Gould and Eldredge proposed that the fossil record appeared the way it does because speciation is not, in fact, slow and steady, but quite rapid. Once a population reaches a large size, however, further changes are damped; it’s much easier for a trait to become fixed in a population of hundreds than in a population of millions or billions. As a result, the species appears “static” in the fossil record over its “lifespan”.
Gould’s *Ever Since Darwin* is probably a good place to start for this. Gould is lucid and explains basic evolutionary theory in terms readily accessible to the layman. He is also (despite being a proponent of one still-hotly debated theory in evolution, punctuated equilibrium) willing to give space to other theories, and to address now-deprecated non-Darwin theories like Lamarckism with respect and context.
This book should be followed up by reading Darwin’s The Origin of Species (still relevant and vital to really understanding the context of the development of modern evolutionary theory), then Gould’s magnum opus The Structure of Evolutionary Theory or Ernst Mayr’s What Evolution Is to gain a more comprehensive understanding of the jargon and structure. After that, dig into Dawkins (earlier stuff like The Selfish Gene or The Blind Watchmaker, not his newer books which are primarily a personal screed against organized religion or theistic belief) to gain some understanding of the neo-Darwinist gene-centric theory and how it complements and competes with the existing modern evolutionary synthesis theory.
Trying to understand the breadth of evolutionary theory from a message board is like asking posters to explain General Relativity; you’re going to get a lot of pop-science glurgage, bits and pieces of explanation, and some jerk (frequently yours truly) who will post a link to the Einstein Field Equations and say, “See, it just takes a little high school math and you, too, can calculate the diameter of the event horizon.” Basic evolutionary theory is actually more accessible, requiring no more mathematics than some basic set theory and a cursory understanding of statistical analysis, but you need to have a comprehensive underpinning in order to weave it all together into the foundation of modern biology.
Environment by itself isn’t the only factor in evolutionary pressure and speciation. Allopatric speciation occurs due to geographical separation, but in peripatric and parapatric speciation, a population group may be separated from the main group but remain in the same functional environment, and evolve due to genetic drift and resource availability. In sympatric speciation, groups will remain in coincident environments but evolve to due a divergence in some characteristic. The passerines of the Galapagos Islands (colloquially known as “Darwin’s Finches” despite the fact that they are not true finches and Darwin originally had no clue during his famous explorations of the significance of the seemingly interrelated speciees) all evolved and speciated in the same environment but each species settled into an individual feeding niches. This was due to the paucity of food and abundance of competition; those members who were capable of extracting food more efficiently than others tended to survive and breed more frequently with similar members, resulting in speciation. (In today’s terms, we would probably call the Galapagos passerines ring species, as some interbreeding does occur, but there are identifiable and unique characteristics that distinguish species.)
In any case, as Blake points out, genus Homo exited the original forested environment, spread into savannah and eventually throughout south and central Eurasia, and evolved into the bipedal, tool-using modern human, H. sapiens. We haven’t been in competition with other apes for a long time; our main competitors have been the indigenous megafauna species of Eurasia (and later of the Americas) which were ill-equipped to cope with talking monkeys (“…ugly sucker, only says ‘ficus’”) and have either largely been co-opted as food, burden, or companion animals, or driven near or to extinction.
Stranger
If I may, the biggest competitors for humans in the sense of another species that could drive us toward or into extinction have been bacteria (notably yersinia pestis, a/k/a the Black Death) and ourselves, since the advent of nuclear weapons. I’m not aware that lions or tigers or bears (oh, my!) ever posed a comparable threat.
Actually, they’d only be competitors if they were killing our prey and plant foods on a large scale. However, I think **Strange **misspoke a bit in lumping grazing animals in with wolves (and other carnivores) as “competitors”.
I doubt that. Any chimp or gorilla could easily outrun me. And they don’t need footwear.
You might be interested to know that the savanah theory explaining up right walking has been seriously challenged. Lucy apparently lived in a forested environment. It has been suggested that upright walking had actually developed when our ancestors were still in the trees. Orangutans actually exhibit straight leg walking at times to efficiently negotiate themselves through the trees.
Well, you have no evidence that our bipedal ancestors had completely left the forest. You are speculating and that is all.
Nope. Few mammals can outrun us in warm climates over any reasonablly long distance. We’re not great sprinters, but we’re great long distance runners. You only need footwear because you’ve been doing so all your life.
A chimp or gorilla could certainly capture you/pass you, easily, sprinting. In a foot race of any distance you would leave them both behind. We did not evolve wearing shoes, by the way, and there is no study that shows that the current vogue for heavily padded running shoes confers any health advantages.
You might be interested to hear that Lucy was very far, genetically, from being a human being. 
She is dated at 3.2 million years ago. The oldest homo sapiens fossils are estimated to be about 195,000 years old. I am not arguing that she could not have lived entirely in a forest, and of course bipedalism would have it’s roots in the forest - it’s hardly as if our ancestors knuckled into the savannah and somehow started walking upright after that (what would they live on without trees? Primates aren’t ruminants, and except us most aren’t good enough hunters to live on animal foods).
What we do know so far is that the oldest human fossils are found in East Africa, and that 190,000 years ago Eastern Africa was predominantly grassy plains. That is enough evidence to assume that homo sapiens was a savannah dweller, and that what makes us unique at least among existing apes (bipedal and taller, great prowess as predators, hairless, sweaty, hence able pursue prey in the heat and sun) has something to do with the fact that unlike them, we were not primarily tree-climbing forest dwellers who thrive eating mostly plant matter.
I just don’t see what any of this has to do with Pygmies, or any other forest dwelling humans (of which there are and always have so far as been found, very few). Obviously humans are capable of exploiting varied habitats and living in many different ways. That has nothing to do with the fact that East Africa 200,000 years ago was a savannah-type enviroment.