falsehoods – Greg Laden's Blog

Is it a Falsehood that Humans Evolve from Apes?

Greg Laden — Fri, 28 Aug 2009 11:10:20 +0000

This is another falsehood, but a tricky one. Remember the point of falsehoods: They are statements that are typically associated with meanings or implications that are misleading or incorrect, and in some cases downright damaging. “Humans evolved from apes” is an excellent example of a falsehood because it is technically correct, yet the implied meanings that arise from it are potentially wrong. Even more importantly, you can’t really analyze the statement “Humans evolved from apes” without getting into an extended analysis and discussion of what an ape is and what a human is.

When most people think “humans evolved from apes” they think of humans and they think of apes (gorillas and chimpanzees) and they imagine the latter evolving into the former. Sometimes people then ask “Well, if apes evolved into humans, why are there still apes? Explain that, Mr. smart scientist guy!!!” or words to that effect. Also, when people think “humans evolved from apes” they may also focus on the word “from” and assume that human ancestors were apes and humans are not. That might be true, but it might not be true.

A priori and without knowledge, one can not assume that the ancient population (species) that was to give rise some modern ape species and to humans was like an ape, or like a human, or something else. There are a lot of possibilities out there. It turns out, and I’ve addressed this elsewhere, that the last common ancestor (LCA) of apes and humans was probably very much like a modern chimpanzee. So, living humans evolved from an ancient ape.

“Aha!” you may say. “Humans DID evolve from apes! Chimp-apes, to be exact!” and that would be a reasonable thing to scream at me. But you’d be missing a key point. The key point is that if you are the average person, you were ASSUMING that the ancestor of apes and humans was ape like because of your Western heteronormative racist Abrahamic biases that cause you to see non-human animals as inherently less evolved and more primitive than humans. You got it right but not because you KNEW something. You were guessing and you got lucky.

Also, it isn’t really completely true that the LCA of humans and chimps was a chimp. It was probably chimp-like, but it may also have been different in important ways, some readily visible if we were to meet up with them (after traveling back in time in a time machine).

Nonetheless, it is true that humans evolved from an ape ancestor, so the statement “humans evolved from apes” actually passes an important test. However, we’ve also seen that there can still be a misunderstanding with respect to the question of living apes not representing ancestral apes just because of some modern idea of primitivism, and the common creationist claim about a species not being able to exist if it gave rise to a different species some time during it’s history. So, you can say in a classroom “Humans evolved from apes” as long as you address these other issues to avoid a misunderstanding. And, you should be testing students with carefully worded multiple choice questions designed to trick them into revealing any misconceptions with which they may have come into the classroom, or that you may have managed to teach them by accident.

But wait, there is another problem with the statement “humans evolved from apes.” This is the part about “from.” The statement that is being made here, by implication, is that there apes, and then there were humans, and they are not the same thing, and one gave rise to another, and humans are not apes.

One could start off an entire course in biological anthropology with this statement and never really resolve it by the end of the semester. Humans are apes phylogenetically, but then again, apes are mammals phylogenetically and to say “apes are mammals” is trivial and uninteresting. It may be that there are interesting and important things about apes that make them apes to the exclusion of aardvarks or some other mammal. For example, if you go with the “apes are apes” idea, then apes are monogamous, 7 to 16 kg in body mass, eat almost exclusively fruit, and locomote almost exclusively by hanging under branches. The fact that this description excludes gorillas, chimps, and bonobos is of little consequence, because the vast majority of ape species are gibbons and siamangs.

“But wait!” you say (I have a feeling I’m going to get yelled at again). “Chimps and gorillas are great apes! When we say ‘apes’ we mean great apes! They are different than the broader category of apes!”

OK, fine, I’ll buy that, but you must now understand that you’ve fallen into my little trap! If great apes are distinct from “the apes” and you want to call them something different because of their body size, their locomotary pattern, their diet, and their mating system, then the same exact argument can be applied to humans, and humans are arguably not “apes” but some other category. Humans do not eat exclusively fruit (they eat mainly grains, roots, fruits, meat); they are similar to the great apes in body size, but not in body size dimorphism. They locomote in an entirely different way, and they have an entirely different mating system. And there are other differences as well.

So, the “from” in “humans evolved from apes” is OK if we want to think of humans as different from apes. Or, if you don’t like that you could say “humans are a form of ape” … (I often mistype from as form and form as from, so to me, it makes little difference!) … I’m not going to tell you that either one is wrong, because I’m agnostic on that point.

However, I tend towards thinking of humans as apes simply because of the pedagogical (and damaging) importance of human exceptionalism. Better that we think of ourselves as a form of ape. Well, actually, better that we think of ourselves as highly inadequate bacteria. But THAT is a different story altogether….

More Falsehoods !!!

This post is one of a series on the topic of falsehoods. The following is a list of falsehoods posts in order:

Falsehood: Nature maintains balance.

Greg Laden — Thu, 27 Aug 2009 11:04:29 +0000

There is a lot of evidence that nature is in balance. An invasive species throws off the balance of nature in a given region by out-competing some similar indigenous form. When something destructive happens there is a return to status quo, eventually. A few cold years are followed by a few warm years, or a few dry years are followed by a few wet years. So, why is “Nature maintains a balance” a falsehood?

Remember what makes a statement a falsehood (refer back to our earlier discussions on this issue). By now you realize that some falsehoods are better than others. “How can a falsehood ever be good?” you may ask. Well, a good falsehood is one that provides an excellent basis for discussion of something interesting. “Nature maintains a balance” is a good falsehood because it opens up more than one can of worms. Let’s just hope that these worms are not invasive species.

The first problem with the statement under consideration is the word “maintains.” Nature might be in balance. The examples I give in the paragraph above, if true, could be evidence of nature being in some kind of balance. Fine (for now). But the belief, under which many people labor, that nature maintains a balance is a bit different than nature being in balance. Nature maintains nothing. Why do I say that nature maintains nothing? You might think because I don’t think nature has a consciousness or can in any way be assigned intentionality. Perhaps I’m saying that nature does not react like many people think it does to good or bad things that happen to it. And if you thought all of these things you’d be partly correct.

But there is a more fundamental reason that I gag when I hear the two words “Nature maintains” … Because there is no such thing as Nature. Well, there is sort of, kind of like there is such a thing as “nouns” or “substance” or “action” or “stuff.” But a statement like “Nature maintains a balance” … this causality wielding construction … assigns the property of sentience or even mere coherence to this thing that we call “nature.” But in realith, what is nature? Perhaps everything that is not dark matter? Including dark matter?

So this is a cool falsehood because it lets us dispose of “Mother Nature” and all her incarnations in one fell swoop. I have not proved that Mother Nature does not exist as anything more than a folk image. I’m simply asserting that if you want to suggest that there is a sentient, reacting balancer entity “out there” that YOU need to come to the table with some proof.

But we are not done with the “Nature maintains a balance” fallacy. The “balance” part of it is also highly questionable. Let’s look at this more closely. What would “balance” look like in nature? Well, we have some examples above with weather. A few years of above average temperature would be balanced by a few years of below average temperature. That feels like a balance to me.

However, this is not really a balance. What is happening here is that there is a system that has (for reasons we’ll ignore for the moment) an average for some linear value (ambient temperature in this case), and random variation around that average. Experientially, you will observe this value being above or below the average almost every year, and since it is random there will be many years where warmer than average is followed by cooler than average, or visa versa. There will be some years where a couple/few years one way is followed by a couple/few years the other way. What you are observing is not balance, but regression towards the mean, a common statistical property of random numbers in series. Add to this a bit of confirmation bias and you have a whole belief system.

Now, having said that, I also have to say that I totally buy that “nature is in balance” with respect to annual temperature. How can I say that after I just said that it wasn’t? Because I’m comfortable with the idea that there is an average and randomness around the average as being like balance. If there were just random variations in temperature (if temperature truly did the “random walk”) then we could have at some point several years where the temperature goes up and up and up until the lakes boil. But that does not happen. There is a kind of balance in that there is a certain amount of energy from the sun, it is dissipated in various ways, and distributed within the troposphere and the oceans a certain way. This ‘balance’ is what we should really call “homeostasis.” And it isn’t really random … a few years of warm followed by a few years of cool could be the result of regular shifts in the homeostasis such as el nino and la nina, which are very regular oscillations in climate that occur over several years. Then there are ice ages and hypsothermals which are major changes in the climatic properties maintained by homeostasis.

(I quickly add: I do think both global temperature and local temperature can be understood as a homeostatic system. However, I’m not sure I would pick this as a prime example of homeostasis if I was trying to explain homeostasis to someone.)

So all of that could be thought of as a complex “balance” in nature. But that is not what people are thinking when they think “Nature maintains a balance.”

The other area where people think of nature being in balance is in the interaction between species. Predators exist to weed out the sick and injured. Plants exist to feed animals. These balance-like concepts are best addressed under the fallacy “Individuals act for the survival of the species” …. which we will address at another time. But we can briefly address another inter-species ‘balance’ concept now.

You have probably heard that when an ecosystem is damaged, it “comes back” …. because nature maintains a balance. If you bulldoze several hundred acres of old forest, eventually there will be old forest there again, for instance. At a larger scale, if continental glaciers march across Canada an the northern US and wipe out all the various habitats, then recede, what was there before will eventually grow back.

Sorry, but no.

Yes, a forest may grow back, but it does not grow back because there is supposed to be a forest in a particular spot, or because nature somehow causes all the plants to do the right thing to reconstruct the forest habitat. If it grows back it does so because this is the eventual outcome of competition among species of plants, and plant animal interactions, that happen to result in forest growing back. I know of habitats in Africa that were once forest, then the forest was cut by humans, and grasslands spread across where the forest grew. Now these grasslands are in parks and forest is starting to grow back in some of them. But in some cases, a certain kind of grass has taken over, and this grass species seems to be dominant and terminal. This is the species that will exist here until some major disturbance or climate change wipes it out. No forest, just Imperata grass, or so it seems.

When Afrikaner trekkers got tired of English colonial rules against things like owning people left the Cape Colony (within the modern Cape provinces, in South Africa) in the 19th century, some of them ‘trekked’ north across a certain part of Namibia. A line of several dozen covered wagons headed north looking for new pasture land. As they drove, the wheels crushed to death the tiny little plants that lived on the stony floor of this desert and left a distinctive mark.

Those marks are still visible today. The plants are still dead. It is not entirely clear how the plants got there to begin with. If “nature maintains a balance”, in this case, nature has checked out.

When ice age glaciers did wipe out the North American flora, a new flora grew back after the ice melted. But although forest tended to come back where forest was before, the dominant species were different each time. We tend to think of North American hardwood forests as dominated by oak and hickory up to a certain latitude, and then maple north of that. Well, other species dominated during the previous interglacial, and before that, other species did as well. The ecological idea of “succession” whereby the same exact sequence of events, with certain pioneer species arriving first, then some other set of species, and finally, a climax flora of specific species at the ‘end’ of the process does not actually happen in nature. That is often what people are thinking when they expect nature to be in balance, but it is not what happens.

Nature is not in balance. But it nature is very big. Disturbance is a vital force in nature, and the name of the game is change. There is resiliency, there is homeostasis, but mostly, nature appears to maintain a balance at the scale of ecosystems and biomes because nature is so big that despite the fact that she is constantly falling over, she never quite hits bottom.

More Falsehoods !!!

This post is one of a series on the topic of falsehoods. The following is a list of falsehoods posts in order: