Personally, I think that most biological drives, maybe all, produce extreme or pathological behavior if unchecked, and that therefore all drives are repressed to some degree in almost all individual humans. There is considerable evidence that things like anger, thirst, or fear (to use highly generalizable terms) are manifest as a balance between limbic circuits that are excitatory or inhibitory; Experimental interference with one or the other circuit produces extreme results such as a rat that will not stop eating or a cat that will maintain an arch-backed bristle-haired stance until it falls over in exhaustion.

Also, I think that what I’m calling drives (again, as a convenience … you won’t find what I am thinking on Wikipedia) are a basic mammalian trait. Therefore, it is reasonable to ask if some of the evolutionary events related to the rise of new species of mammals are related to changes in drives, or more interestingly (and more commonly, I suspect) changes in how drives are on one hand repressed and on the other hand re-configured to work with each other.

Thus, one could say that since humans are behaviorally derived with respect to many traits in comparison to African apes in general, a major feature of the human brain must be mechanisms telling the rest of the brain, to some extent every minute of the day, “Don’t be a chimp …. Don’t be a chimp. Seriously, dood … don’t be a chimp.”

At the individual level, and I’m oversimplifying a great deal here, one might imagine drives being enhanced or repressed to a degree that makes an individual very different from others. The fictional character “Brennan” on the TV series Bones comes to mind. She seems most of the time to have no drives at all, or to be intellectually in denial of them. Social and psychological pathologies may often be associated with drives that are inappropriately strong or weak.

So, is it really true that behaviors are not “caused by genes” if there are these drives? Yes, and I say this because the average person who is thinking that behaviors are caused by genes is not thinking at all about intermediate mechanisms, and if they are, they are assuming that the intermediate mechanisms are little more than a transparent ether through which genes operate on the behavioral phenotypes we observe. Also, “genetic determinism” is not about whether or not one or more genes are involved in a trait, but rather (and this is very important so if you’ve got a yellow highlighter uncap it now) “genetic determinism” is about the close correspondence between variation across individuals in the genetic code they carry and the ensuing variation across individuals in the phenotype they express. Moreover, “genetic determinism” as usually conceived is presumed to average out within categories such as “race” or “sex” with very little variation within, but enough variation between these categories to be measurable. Which is why the concept is almost always racist or sexist or both.

But in reality, variation in the way limbic and other brain functions as well as closely related endocrine systems are manifest in humans and probably many other mammals is only to a small extent a function of genes, and is otherwise a function of what we may loosely call development. This relationship is not a post-hoc observation, or a liberal excuse, or a politically motivated bit of rhetoric. It is, rather, the explanation for why we have large brains that mostly develop, in detail, on the basis of experience rather than genetic coding for how they are hooked up. (And, while this applies mainly to mammals, something like it might be going on in some birds.)

Consider long term habituation. When endocrinologists (those who study hormones) measure hormone levels, they generally adjust the numbers to account for individual baselines, because while two individuals may have very different baselines they can have the same range of behaviors and responses. Two men may have androgen hormone levels that vary between them by a factor of 2X or 3X, but have the same basic behavioral repertoire. This is because of two things: First, the number of receptor sites and their sensitivity matters as much as, if not more than, the serum hormone levels; and second, most hormone systems are some sort of feedback loop that relies on changes in concentration against set points that are individually established, not species-specific. Putting it another way, if a hormone system is like a thermostat in your house (a homeostatic equilibrium system) then each individual has a personally established and potentially unique “room temperature.” This variation between individuals could be genetic, but is it just as likely, or even more likely, to be developmental. A related example is the mechanism by which we become “cold” or “warm” (with respect to comfort). This is not innate, but rather, a function of exposure to environmental conditions in early life (thigh there are body-shape related variations that probably are genetic that matter to thermoregulation in a non-industrial population).

Given huge piles of evidence for individual variation in behavior as a function of context, conditioning, and development and relatively little evidence that has not been made up, cooked up, or otherwise tainted or damaged for straight forward genetic determination of behavior, I’m going to go with the model that humans vary mostly on the basis of their biological and cultural experiences post-conception. For example, the single largest factor in variation in human intelligence in a given population can easily be prenatal alcohol exposure, or variation in folic acid in the maternal diet. Given the amount of post-conception stuff the brain does in development, and how much of that depends on experience, it is very unlikely that brain function varies across individuals on the basis of genes (other than individuals with genetic disorders, but we need not count broken individuals in considering normative development).

From what we know about “drives” and from what we know about brains and development, it is very reasonable to hypothesize that variation across individual human males in something like violence levels, likelihood to carry out rape, or other widespread and usually male-associated behavior is environmental. Yet, these behaviors at the base, the systemic potential for these behaviors, is a mammalian feature or a primate feature or a great-ape feature, depending on level of analysis.

This is not the place to discuss this in detail, but a quick digression regarding comparison among mammals is probably useful at this point in order to stem unnecessary direct comparisons that may come up in discussion. Maybe mammalian males in general have certain traits leading them towards violent or icky behavior, but the details are important. The fact that big horn sheep butt heads in contests sometimes to the death, taken as an extreme male-male competitive trait, can not be linked to similar behavior among human males (and such behavior does seem to happen in humans). The basal bovid-type organisms from which the big horn sheep derive was probably a small bodied monogamous forest dwelling animal in which males probably did not have a much greater tendency to butt heads than females, though both males and females would likely have employed some sort of “violence” in defending young or territories. Among primates, Old World Monkeys include a lot more examples of violent male behavior than do New World Monkeys. The latter group, in fact, have many cases of distinctly non-violent males as typical of the species. We don’t know the nature of the basal primate, but we cannot assume that it was like a baboon, which is the primate often taken as prototypical in thinking about primate social behavior. In fact, we can guess that it was probably NOT like a baboon for a number of reasons. Therefore, what might be thought of as “over the top” male behavior (butting heads to the death) is NOT a basal mammalian trait that may be found in humans because we are mammals. The phylogenetic link between big horn sheep and human football players is non-existent. (This is why many of us cringe with the latest “evolutionary psychology” finding!) Rather, violence in human males is either derived in our species or in a set of species closely related, including perhaps the great apes, or apes in general, or some other subset of Old World primates.

And, this would be a matter of evolution of drives in a very general sense which are then shaped in a maturing individual by other developmental tendencies and in social beings with large brains, buy culture.

Which brings us to the famous YanSan comparison.

There is an intellectual and pedagogic tradition that comes from people working out of a handful of American Universities (originally, Berkeley, Chicago and Harvard, but then other places such as Madison) having to do with the study of both primates and human foragers. The details are interesting but this is not the place for them. What is important is this: A lot of us (and I’m part of that tradition) learned some of our best metaphors, for doing both research and teaching, from Irv DeVore, who either came up with them himself or consolidated them from people with whom he overlapped or worked, such as Sherwood Washburn, George Gaylord Simpson, and others. And one of those tidbits, which is a comparison and a set of stories much larger than your average metaphor, is the YanSan comparison.

It runs like this. Imagine a Yanomamo village in the Amazon. The Yan (short for Yanomamo) live in a society that for various reasons incorporates a fair amount of violence among men. Men who have killed other men are given a special name of respect, tend to have more children than other men, and often have two wives (in a society in which while polygyny is allowed, it is rare). Then, in contrast, imagine a “San” (Busheman) community in southern Africa. The San live in a society of hunter-gatherers where variation in status among men, for any reason at all, is discouraged, and interpersonal violence is frowned upon. Among the Yan, disputes are settled with chest pounding duels or axe fights, while among the San, disputes are settled by endless discussion during which there might even be hugging.

That’s the background. The YanSan comparison itself goes like this:
In the day to day course of events, a Yan child may become upset or agitated as children occasionally do, perhaps in relation to another child. The good Yan father steps in. He brings his son to the center of the community courtyard and calls over the other child with whom the conflict has arisen, and that child’s’ father tags along. The two Yan dads equip the children with poles about the length of their bodies and set them up to whack at each other until one of them succumbs to injury. Or perhaps, instead of using the poles (because that can be dangerous … you can poke your eye out with one of those things) the dads teach the 6 year olds the rudimentary form of the chest pounding duel, in which each participant gets one free shot at the other’s chest, and you can use one fist or two to pound on your opponent. The participants go back and forth taking fee shots at each other’s chest until one falls to the ground. The one still standing wins.

Meanwhile, over in the San society which is entirely different, a perturbed child is treated differently. If a toddler or youngster is very upset, yelling, having a tantrum, any nearby adult who knows the child, often but not always a relative, will hold the child in both arms until he calms down (this can take considerable time), and then spend some time soothing the boy and telling him thoughtful thoughts.

In both cases, there is a set of drives typical for men, and there is a society in which there is expected, normative male behavior. But since the expected behavior is very different between the two societies the developmental process has a lot of work to do. Boys will not on their own grow up to be Yanomamo warriors with the proper kind of fierceness, and boys will not on their own grow up to be San hunters with a proper cooperative attitude, unless a great deal of cultural energy is expended.

And this is facilitated by the existence of childhood, which may well be Homo sapiens most important adaptation. The YanSan comparison exemplifies how humans transit from blastosphere to adult with respect to behavior, and demonstrates that there is a great deal of potential variation in what the result is, and thus, there is great potential variation in the sorts of societies that Homo sapiens can come up with.

But males are still demonic.

What I mean by that is this: Across all human societies, even when there is relative equality between males and females in power or other measures, males are the more violent sex on average. When human societies range into more violent normative behavior, it is males who are in the vanguard virtually all the time. There are plenty of cases where females are also violent, but they are comparatively rare and less extreme.

And, there are patterns to this behavior seen across society, and interestingly, there are even patterns of male behavior when males are viewed across species, as per the above discussion, among the great apes and in particular comparing chimps and humans. Those patterns may be accidental, they may be nothing more than basic mammalian behavior (or the behavior of an internally fertilizing lactating creature, on whatever planet it is found) and thus almost too basic to be meaningful, or they could be patterns around the specific nature of ape social systems, of which chimpanzees and humans have their own similar yet different versions.

Some years ago, Richard Wrangham, emerging as a leading primatologist, was woo’ed away from his home in Michigan by Harvard to do research and teach interesting courses. One of the courses he developed in his new milieu and taught to advanced undergrads in bioanthropology was about male behavior in apes, looking at the behavioral biology and culture of this behavior, seeking patterns, similarities, contrasts, etc. Over a short period of time this course became very popular. Knee-jerk feminists responded to the course with great disdain because it seemed to be biological determinism, but then some went ahead and took it anyway and found out that it was not. And eventually the course became a book: Demonic Males: Apes and the Origins of Human Violence

Many have criticized Wrangham’s book for suggesting that simple underlying genetic systems determine things like gang violence in humans, but few who have read the book have come away thinking that. It may well be that Wrangham’s view is somewhat deterministic, but that is hardly the point of the study. And, if you bring to the discussion, as Wrangham does, the concept of “drives” or similar psychological phenomena as I’ve described above, the genetic determinism that might be inherent in many comparisons between species’ behavior rather fades away. More interesting, though, may be the political nature of the problem of determinism, and this relates to the ongoing discussion of male privilege as well as to a previous discussion we’ve had on this blog about rape. Is it possible to attain the ideal feminist society (towards which we all strive) if male and female drives are somewhat different, and male drives are (or at least some of them are) so … dickish?

… a new philosophy has emerged in the last decades, an evolutionary brand of feminism that sees the emergence of patriarchy as an intimate part of human biology. Evolutionary feminists, writers like Patricia Gowaty, Sarah Hrdy, Meredith Small, and Barbara Smuts, agree with traditional feminists about the evils of patriarchy, but they do not disconnect humans from their biological past. The logic of evolutionary feminists appreciates the rich details of patriarchal history as recounted by historian Gerda Lerner, but it simultaneously rejects the notion of plumbing the human condition through reading merely the last 6,000 years of history.

Evolutionary feminists … would insist that people can think about the evolutionary pressures that elicit rape, for example or other forms of violence, without necessitating any absurd pronouncement that because rape is “natural” it is in any way forgivable. After all, no one considers the case of the black widow spider, who kills and eats her male counterpart after mating, to mean that murder and cannibalism are okay. …

Patriarchy is worldwide and history-wide, and its origins are detectable in the social lives of chimpanzees. It serves the reproductive purposes of the men who maintain the system. Patriarchy comes from biology in the sense that it emerges from men’s temperaments, out of their evolutionarily derived efforts to control women and at the same time have solidarity with fellow men in competition against outsiders.

(Wrangham 1996 pp 124-125)

It is interesting to consider the commentary emerging (mainly in comments but also in a few blog posts) around Rebeccapocalypse in light of this discussion. Most commenters are either on board with giving women the right to set their own level of concern about potentially dangerous men (those are the feminists) or they re busy making excuses or denying the demonic nature of male Homo sapiens. While many of the former are men (it might be about 50:50 men:women) the vast majority of the latter are men.

Just sayin’

In homage to an inspiration of this post, I provide this link to the secret, generally unseen obituary of Professor Irven Boyd DeVore.

With never-before-seen video, primatologist Isabel Behncke Izquierdo (a TED Fellow) shows how bonobo ape society learns from constantly playing — solo, with friends, even as a prelude to sex. Indeed, play appears to be the bonobos’ key to problem-solving and avoiding conflict. If it works for our close cousins, why not for us?

I have written before about the “Hauser Effect” and therefore I feel a need to look into the current allegations that scientific research misconduct happened in Hauser’s primate research lab in William James Hall. Could it be that the Hauser Effect is really just misconduct? Alternatively, could it be that what is seen as misconduct is really the Hauser effect? Could it be that there is some complex interconnected process going on here that happened one way in Hauser’s lab but happens generally in science (and human thinking in general)?

Very simply put, the Hauser effect has two levels of manifestation, one particularistic and one general. The particularistic level is this: Researchers working with the usual Old World primates, such as chimpanzees, baboons, and macaques, discover a phenomenon that can only be seen in chimpanzees to the exclusion of the other primates, suggesting that it is a capacity relevant to ape evolution, not found in other primates, and potentially relevant in some general way to human evolution.

Then, Marc Hauser produces a paper in which he shows that his monkeys can do it too. His monkeys, the cotton top tamarins, are New World monkeys of the family Callitrichidae. Mark got his monkeys to pass the Gallup Test. He got his monkeys to count. I heard the other day that he had his monkeys dancing backwards and in high heels. While chewing gum.

(OK, I’m joking about the last one, but the others are true.)

The more general form of the Hauser effect is this: You have a phylogenetic tree, with one branch consistently showing a set of derived traits, derived with respect to the rest of the tree. Like, apes can pass the Gallup test (can you recognize that the thing you see in the mirror is YOU and not just some other primate?). That’s not the Hauser effect. The Hauser effect is when another branch, one not adjacent to (or even near) the derived branch, consistently shows similar derived traits, again and again, almost mockingly of the nice neat pattern seen elsewhere on the evolutionary tree.

There are three explanations that I’ve considered for the Hauser effect: 1) The trait s really there in all or most members of the larger tree in some form that is usually invisible except in certain lineages because of the way we generally interface with the animals. For instance, at one point in time we could see the Gallup effect in orangs and chimps but not in gorillas, in a test setting, but researchers had in fact observed one gorilla using a mirror with clear self recognition, outside of the context of the test. Gorillas, perhaps, are doing something differently in the laboratory setting. Or the putative results of elephants having various cognitive abilities, but whereby those abilities must be tested for using different, non-visual, modalities in order to make comparisons with highly visual apes. 2) Parallelism. Always interesting, in this case not as interesting as other possibilities. In this case, the ability just happened to evolve twice, perhaps because off some similarity in ecological or social context (a very likely explanation for the cotton-top’s behavior). 3) The master experimenter phenomenon. A master designer of experiments, and Marc Hauser is one, could overcome reason 1 and find the effect if it is there. Marc would have gotten Koko the gorilla to check her hair in a mirror during the lab tests rather than only as a casual activity in the hallway on the way back to her enclosure. But a master experimenter may also be able to do something else, which no one else can do. A master may be able to make earthworms sing jingle bells, fleas design new kinds of computer circuits, and giraffes tap dance. Well, I exaggerate. A master experimenter can make dolphins dance, horses count, and New World monkeys act like chimps. And yes, that mention of horses is a reference to clever Hans.

Clever Hans was the horse that could to math. We now think, looking back on Clever Hans, who performed the trick for many audiences over many years, that the horse’s keeper unwittingly gave clues to the horse telling it when to stop enumerating with it’s hoof. Ask the horse “Hans, what is five minus two” and the horse knows to start stomping its hoof. Then, an unconscious cue is given by the horse’s keeper … like a poker player’s tell … when the horse hits the number ‘three’ and this tells Hans to stop. So, it turns out that the horse can’t do math. But it can read subtle cues unknowingly exhibited by a human that no other humans picked up on for years. Stupid horse.

For whatever reason, Marc Hauser’s monkeys did things that were surprising. Considering how little we know about the landscape of behavioral capacities of New World Monkeys (as opposed to the much more studied Old World Monkeys like macaques and baboons) we might be able to conclude that the NWM branch is simply more ape-like than the OWM branch of primates. This is surprising, interesting, and untested … more work would have to be done with more New World Monkeys. But there may be reasons to not be that surprised. New World Monkeys spend more time in multi-species associations than OWM’s do. Callitrichids have an unusual mating and offspring rearing system that may require more personal political savvy than other monkeys, or at least, a different kind. There are all kinds of reasons that Marc’s monkeys impress, technically it is always a case of the Hauser effect (as narrowly defined above) regardless of the reason. The reason being, in my mind, either that the monkeys are different, or that Marc is smarter than the average experimenter, possibly too much smarter.

Fraud or misconduct never crossed my mind. I have read nothing about the specific accusations, and I have no secret inside knowledge. And, in fact, I wanted to get these thoughts down on ‘paper’ and on my blog for others to see before I learned anything more about Marc’s situation.

I’m like the neighbor who is interviewed after the spectacular arrest of the guy down the street for some over the top crime.

“Marc kept to himself, in his lab. He produced his papers, got on with his job. Nobody ever thought he would carry out misconduct. He wasn’t the type. I can’t believe this is happening.”

That’s what I think.

The fossil was found while University of Michigan paleontologist Iyad Zalmout was busy looking for dinosaur fossils in western Saudi Arabia. He found the monkey, from a much later time period, instead. Ooops.

“I didn’t know whether to be disappointed or not, but I thought, well, maybe something interesting will pop up here, so I started looking around. Within minutes, I found teeth sticking out of the ground, and when I realized what they were I was shocked. I had worked with Phil [Gingerich] on terrestrial mammals in the Bighorn Basin, and my first look at the size and shape of these teeth told me I had found a primitive primate.”

Zalmout sent a photo to Philip Gingerich, top monkey fossil expert, who confirmed its primate status and potential importance.

Major early Oligocene to early middle Miocene Afro-Arabian catarrhine primate sites. Key: 1, Harrat Al Ujayfa, Saudi Arabia; 2, Thaytiniti, Oman; 3, Taqah, Oman; 4, Fayum, Egypt; 5, Gebel Zelten, Libya; 6, Lothidok, Kenya; 7, Meswa Bridge, Kenya; 8, Koru, Kenya; 9, Songhor, Kenya; 10, Buluk, Kenya; 11, Moroto, Uganda; 12, Napak, Uganda; 13, Kalodirr, Kenya; 14, Rusinga, Kenya; 15, Loperot, Kenya; 16, Ryskop, South Africa; 17, Wadi Moghara, Egypt; 18, Ad Dabtiyah, Saudi Arabia; 19, Malembe, Angola. Map and caption from original paper.

The time period in question, the Oligocene, is circled on this time chart from the USGS.

African “higher” primates, the Old World Monkeys and the Apes, are collectively known as the Catarrhini. The Catarrhini split from the New World monkeys at least 40 million years ago, though this date is subject to revision. That would be somewhere in the middle of the Eocene. Later on during the late Eocene and subsequent Oligocene, around 20-something mya to 30-something mya, Catarrhini gave rise to populations that would have been the ancestors of the major living groups as well as some lineages that have gone totally extinct. The split between living Old World Monkeys and the apes would have been somewhere in the middle of this time range.

Saadanius hijazensis in situ. The fossil, found in 2009, preserves most of the face, the front upper portion of the skull, the temporal bone, and the palate, with some of the left and right upper teeth. The specimen was found with the palate and teeth facing upward, imbedded in an iron-rich clastic conglomerate in the middle part of the Shumaysi Formation. Credit: Iyad S. Zalmout, University of Michigan Museum of Paleontology

Frontal view of Saadanius hijazensis (holotype SGS-UM 2009-002). source

Within a relatively short time span, several ape lineages arose, causing much subsequent confusion among palaentologists. The short version of the story is that some four major ape lineages emerged between the middle Oligocene and the end of the Oligocene (around 23 mya), most of which we tentatively refer to today as “Apes of ancient aspect,” with all of those being extinct, and one lucky lineage that is not extinct, the “Apes of modern aspect.” (The latter get to be “modern” because they are more derived than the others.) You would be safe thinking of the latter as the “hominoids” and the others as “Miocene apes” since they mostly lived in the Miocene and the “hominoids” kept it simple by leaving very few fossils behind. Today, when we try to piece these apes together into a coherent pattern, to understand what form of ape gave rise to what other form of ape, we become confused and argue. If only we had a better idea of what the ancestral species of all these apes looked like, in order to test hypotheses about ape evolution in the early days.

Videoscan of the face of Saadanius hijazensis, a new genus and species of primate that lived in the Arabian Peninsula during the late Oligocene epoch, 29-28 million years before present. nsfnsf

Meanwhile, over on the Old World Monkey lineage, there was much less diversification and a relatively straight forward body plan easily represented by macaques or baboons persisted to modern times (though it is a bit more complex than that).

Thick solid vertical lines indicate known temporal ranges of taxa; thick dotted vertical lines show intervals of occurrence or possible extension for temporal ranges of taxa. Diagram and caption from original paper.

Now, here’s the rub: We have some fossils (Propliopithecoidea)from around 30-35 mya that show us what the ancestor to this complex series of developments look like, and we have what are essentially modern Old World Monkeys and Apes, and a fairly large collection of Miocene apes (of ancient aspect) post dating 23 million years ago. For the monkeys specifically, there are bits and pieces but mainly fossils that look pretty much like modern moneys and date to the last 5 mya or so.

In order to understand the evolution of a set of species, it is necessary to know about the nodes … the common ancestors of various sets of species. Ideally, we would have a good understanding of the population that gave rise to the Old World Monkeys and the Apes, so we could sort out differences among subsequent lineages with a knowledge of what specific traits are expected to be present in given animal because its ancestors had it. In other words, is a certain trait seen in one species and not another, sister species, because it was added by the first species, or lost in the second species?

There is a major difficulty in figuring this out with primates: The primates, with respect to untangling fossils, have three overwhelmingly important characteristics. First off, Many of the lineages are extinct and left incomplete fossil records. DNA can’t help us with them an the scrappy fossil are not exactly coming to the plate.

Second, the physical form of Catarrhini (many of the living and extinct apes and monkeys of the old world) is highly selected to adapt to arboreal lifeways. All species have selective forces working on them, but some selective forces are stronger and more overwhelming than others. The key characteristic of birds is flight. There are few features of flying birds that are not shaped directly or (barely) indirectly by the requirements of flight. The key characteristic of a moose is that it eats aquatic vegetation seasonally and lives in the snow the rest of the year. So it has long legs. Big whoop. The shape of, say, the top of the head of the moose is not adapted to this characteristic, but for birds, every part is shaped by the flight adaptation. Large mammalian arboreal species are not as constrained as vertebrates that fly, but they are fairly constrained. (I do simplify … some primates are not as arboreal as others, and the constraint I mention here is more severe in the New World where arboreality is much more intense.) The result of this constraint is that some features are either very conserved (once they emerge) or are converged on over time from multiple directions. This confuses us.

Third, we are talking about a long period of time with a spotty fossil record. Any kind of confusing convergence or random loss of a feature or other complexities that might occur over time is more likely in a very time-deep fossil record. Think of it this way: Monkeys and apes are evolving (from monkeys and apes) over and over across vast periods of time. In enough time to see the evolution of monkeys or apes from non-monkey or ape ancestors occur several times, the same lineages are traveling the adaptive landscapes altered by both random and adaptive forces that themselves are changing over time.

So, imagine a family tree with prosimians and New World Monkeys represented as lower branching events, and then two focal living groups, the Old World Monkeys and the Apes as two additional tips that we presume to join subsequent to the split with Old World Monkeys, but with no real fossil record at the point of that split. We can’t be sure of much of what is going on there. For instance, if a fossil that looks ape like (but this is only one bone or some teeth) is found from a deposit around 25 million years ago, does a particular feature of that fossil indicate that it post-dates the monkey-ape common ancestor (because it is novel, not seen in the last common ancestor) or does it indicate nothing other than membership in the Catarrhini (becuase the feature is seen in the last common ancestor)? Without a detailed set of information about the last common ancestor, we can’t say, and can thus not be sure of this fossil or what it tells us about the timing and nature of the ape-monkey split or other important questions.

So, Saadanius hijazensis is a missing link right? It represents the last common ancestor of Old World Monkeys and the Apes. Problem solved!

Well, no, unfortunately not, but Saadanius hijazensis is close to the last common ancestor and is thus very helpful. Saadanius hijazensis is considered to be close to the base of the ape-human clade. Not “the missing link” but very very helpful in understanding what the ape and monkey lineages we know of for later periods evolved from.

Saadanius hijazensis has a tubular ectotympanic (the bone that contains the canal runnig to the ear from the outside). This is a features that separates the Old World Monkesy from the earlier-split-off New World Monkeys, shared by the Old World Monkeys and living and Miocene Apes. So Saadanius hijazensis is a Catarrhini. Miocene apes have frontal sinuses, palates that are less uniform in size front to back than monkeys, really large male canine crowns, a few other esoteric tooth-related features, and are typically large. Saadanius hijazensis lacks these features, making it not an ape. Compared to the above mentioned really early primate fossils (from the Eocene), Saadanius hijazensis is similar but different in the ways one would expect if it was an Old World Monkey. And, the fossil seems to date from prior to, but just prior to, the monkey-ape split.

These facts together put Saadanius hijazensis near the common ancestor of Old World Monkeys and Apes, in both time and morphology. The fossil is found in the Arabian Peninsula, which at the time was part of Northeast Africa (the Red Sea did not exist yet) which places the fossil in space within a region (a very large region) thought to be the location of the evolution of these monkeys and apes. And, although this could quite accidently turn into a tautology, Saadanius hijazensis helps to pin down the timing of the split to about 23 to 25 million years ago, simply because it fits nicely with a morphology representing the pre-split form and dates to that period. This does not rule out an earlier split, of course, because Saadanius hijazensis could certainly represent an earlier evolutionary event. With respect to the timing of the monkey-ape split Saadanius hijazensis also provides hope that more fossils of this time period can be found, and although a single species may be hard to place in fossil space-time, a set of species can reveal a pattern that may make for interesting study.

Given this position, Saadanius hijazensis can help resolve conflicts regarding early Miocene apes, since Saadanius hijazensis approximates the ancestor from which they evolved, and help to understand (given further analysis) the behavioral biology of the Old World primates of that period. For instance, did the ancestor of the living apes have a flat face (like a gibbon) or a long snout (like many monkeys including baboons). According to my old friend and schoolmate, Laura MacLatchy, this fossil should cause us to lean towards the baboon-face model.

Here’s a Nature video about the fossil:

Zalmout, I., Sanders, W., MacLatchy, L., Gunnell, G., Al-Mufarreh, Y., Ali, M., Nasser, A., Al-Masari, A., Al-Sobhi, S., Nadhra, A., Matari, A., Wilson, J., & Gingerich, P. (2010). New Oligocene primate from Saudi Arabia and the divergence of apes and Old World monkeys Nature, 466 (7304), 360-364 DOI: 10.1038/nature09094

A University of Michigan press report on the find is here.

How about this one: Is it a Falsehood that Humans did NOT evolve from Apes????

Yes and no. Humans descend from a population of primates from which other apes also descended (minimally the two species of living chimps) and which was part of the panoply of late Miocene forms, all related to each other, that we call apes. So yes, humans evolved from apes.

There are people who don’t believe that. They, creationists, think that apes are apes and humans came from somewhere else, like the Garden of Eden or Mud or whatever. (This may depend on which flavor of creationist and, frankly, which humans the creationist is talking about … by some creationist theories, white people came from Eden, while various brown people came from various mud, and Jews came from monkeys.) When creationists object to the phrase “Humans evolved from apes” evolutionary biologists tend to respond with a long list of reasons that we should assume that humans and chimps DID evolve from a common ancestor which was an ape of some kind.

People who are not creationists, but still prefer some kind of human exceptionalism, may not like the phrase because it strongly implies that humans are apes, and they may prefer that we be thought of as different from apes.

Either way, we need to understand that the phrase “Humans evolved from apes” has two distinct meanings for people who hear it. One emphasizes the word “apes” and the other emphasizes the word “from.” By one way of thinking, the phrase means “Homo sapiens is one of several species of ape.” By the other way of thinking, the phrase means “Homo sapiens evolved from apes into something different.” Either way, some people will be annoyed. Either way, the statement may be correct.

When science educators, hear resistance to a phrase linking humans to apes, we tend to want to push the humans back in with the apes right away. We don’t want to encourage any sort of human exceptionalism, or any sort of random nonsense about how evolution didn’t happen. And, a natural extension to that way of thinking is to insist that humans are apes. Fully, unexceptionally, undeniably, apes.

Putting this in a slightly different, perhaps demented matter: “Humans evolved from apes” is wrong because “Humans evolved from apes.”

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 discussion of what an ape is and what a human is. And this is a trick one: The reason “humans evolved from apes” is false has nothing to do with the fact that it is true (which it is). It has to do with what is going on in people’s minds when they think “humans” (or “apes” or “evolved” or “from”).

So, how true is the statement that “humans ARE apes?” 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, “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….

As an experiment in both thinking about this and pedagogy, I’ve written part of the above discussion in a different way. Have a look:

The Kladistic Konundrum …

Cladists like to point out that a monophyletic (all related to each other and not distributed across a set of evolutionary branches with extra twigs in there) group is a member of the larger monophyletic group to which it blongs. Thus, a human is an ape, an ape is a primate, a primate is a mammal, and so on and so forth. Therefore, plain and simple, “humans are apes.” Anything that looks or smells like a contradiction to that is necessarily wrong.

This “cladistic requirement” is true, but it is sometimes misapplied. This is because a perfectly good monophyletic group can be joined with, or even infiltrated by, a perfectly good alternative category that is actually meaningful. For instance, it appears based on recent genetic research that polar bears are a form of brown bears. There is one species of brown bear seen as numerous populations including the Kodiak bear, the grizzly bear, the European brown bear, etc. Within this clade, as a branch not adjoining the brown bears but within them, is one population that happens to be maritime adapted and white. The polar bear. So, we have a separate species sitting there within a clump of closely related populations.

Does this mean that the numerous derived adaptations seen in polar bears are less important than they otherwise might seem, and the polar bear is just a subspecies of brown bear? Or, does it mean that there are several species of brown bear, rather than several populations, and one of them is white and eats seals? Yes, both could be true, depending on what you think is important. It think, though, that most people would keep the brown bears as one species and the polar bears as another species, and simply admit, despite the cladistic requirement, that a new “kind” of bear has emerged from another. Perhaps some day there will be multiple species of polar bear descending from this current form.

The following little conundrum illustrates the triviality (and misleading nature of) the cladistic requirement in relation to the question at hand (humans evolving from apes, or not).

When most people say “humans are apes” they do not mean that humans are “small bodied almost exclusively arboreal fruit-eating suspensory monogamous primates” which is what the vast majority of apes are, given that this describes gibbons and siamangs, and most apes are gibbons and siamangs.

Yes, it is true that apes can be divided into lesser apes and great apes. The lesser apes diversified first, the great apes later. So, why are the great apes not just a form of lesser apes? If your claim that humans “are” apes because they (hominids) diversified from an ape population is valid, then that logic MUST be applied to the other apes, so great apes are lesser apes.

Therefore, when a person says “humans are apes” they mean that humans are “small bodied almost exclusively arboreal fruit suspensory eating monogamous primates. Which they’re not. And, have they realized they were saying that, they probably would have put it differently.

Note: Other blog posts in the Falsehoods II series can be found here. The current falsehood is part of this installment of “Everything you know is sort of wrong” on Skeptically Speaking radio.

It is probably not a coincidence that two of the three subspecies of gorilla live within sight of each other (and of the main subspecies, the lowland gorilla) within this region. The Virunga volcanoes are not old enough to have supported island forests for the evolution of these specific subspecies, but other highlands in the region, or other volcanoes (perhaps in the Eastern Rift) may well have been the location in which they evolved.

And, as it turns out, there is reason to believe that the split between chimps and humans occurred on one of these volcanic mountain tops several million years ago. Or, at least, in an environment geologically similar to the upper reaches of the Virunga Volcanoes. But to tell this story right, I have to go back a few years.

… distant in the background African sounding drum music, distant thunder, polyphonic singing fades to the sound of steel on rock as dozens of workers are excavating elephant bones in the dusty windswept African plain under the watchful eyes of the Rwenzori …

The Congo. Parc National de Virunga, well north of the Virunga Volcanoes, north of Lake ex-Edward. I was with a fairly large expedition. At the time we had been waiting for crucial supplies, including tents and cots and other accouterments of field life, to arrive in a truck the expedition had purchased in Kinshasa, which was being driven to the field site via the Central African Republic (there are no roads that traverse the Congo). The truck was several weeks late. So, on the occasion that we heard a vehicle on the nearby park road (once or twice a week), we had taken to chanting the name of the driver of the truck (Leo) while facing a mock-up of the truck made by a local school kid, that we had placed in a makeshift shrine under a tree near our dining area.

“Leo… Leo…. Leeeeoooooo….” we were chanting one day, in observance of our cargo cult, as we heard a vehicle driving down the road, well out of sight to the east.

When the sound of the vehicle suddenly shifted, with gears lowering, near the juncture of the main park road and the side road leading down to our research site, we didn’t think much of it. The large muddy puddle at that spot caused all vehicles to down shift and slow. But this time, the vehicle in question stayed in low gear and we could hear it getting slowly closer to us… this truck had turned in to the research camp road! It was Leo! Leo had arrived with the tents and cots and the garlic and the other stuff!

But when the vehicle finally came in sight after traversing the 3 kilometer path that lead to our camp, we were very disappointed to see that it was not The Truck driven by Leo with Our Stuff. Rather, it was someone we did not know in a Land Rover.

Visitors.

The visitors turned out to be a chimpanzee conservation specialist on contract with the United Nations and her driver. She was on her way south to the Virunga Volcanoes to habituate the chimpanzees in one of the mountain top forest patches to tourism. That is similar to habituating the chimpanzees to researchers, but instead of wearing khaki’s and carrying around notebooks … so the chimps get used to that … you wear loud print Hawaiian shirts with cheap cameras hanging around your neck and carry tour books and gin and tonics. So the chimps get used to that. I assume.

Anyway, the chimp conservation specialist eventualy moved on and went to the Virungas. I eventually (several months later) moved on and went to Cambridge Massachusetts, where I lived at the time (plus or minus) when I was not in the Congo.

And my first night in Cambridge had me crashing at the home of Irv DeVore, my advisor, the famous primatologist and forager researcher. Also crashing at DeVore’s was Richard Wrangham, famous primatologist who at the time was being courted by Harvard, and was thus visiting from Michigan.

Richard and I had a conversation. It turns out that he had met up with the UN chimpologist in the Virungas at some point when I was at the other end of the park (this park is big … traversing it the long way is not normally done, but when it is it can take a couple of days and you quite seriously risk your life). This led to an interesting conversation.

Richard and I started to exchange information and ideas. I had been looking at the use of roots by foragers in the Ituri Rainforest, and Richard had found out something interesting about the Virunga chimps:

The upper slopes of the volcanoes have porous soils and rock, and no habitual lakes, ponds or long-lived streams. Water falls from the sky and disappears beneath the surface of the volcano, to come out near the base of the mountain as springs, but in the main not accessible for drinking by the denizens of the high forest itself. Animals that live in the forest get their water mainly from very short lived puddles on the surface or from tree crotches, where branches separate and tiny puddles form, and possibly from canopy plants that hold water. During the two month dry season these sources of water dry up and any animal that requires daily drinking must migrate out of the forest or die.

But the chimps, who do require daily access to water, don’t migrate out of the forest. They can’t. The habitat they live in is circumscribed and can’t leave. Well, individual chimps probably do leave now and then and some of them manage to find other suitable chimp habitats, but for the most part the chimps are trapped in a habitat without drinkable surface water for seven to ten weeks or so per year.

It turns out that the plants that live in this habitat are also water stressed, and some of them have interesting evolved adaptations to this. One viney plant, a kind of yam, has evolved a huge underground storage organ that swells as it collects water all year, then provides water during the dry season.

This yam is about the size of a coffee table or maybe a small couch. That is quite large for a yam. And it is loaded with water.

And … you guessed it: The chimps dig these tubers up and drink from them during the dry season.

This may or may not impress you but it should. Of all the species of vertebrates, hardly any use roots of any kind for any reason. Probably only mammals. Of mammals, bears, pigs, and rodents include species that use roots to some extent. Among primates it is not generally thought of as a major adaptation. Nearly 300 species of primates have fewer than four or five (including these chimps and humans) that ever use roots. And these chimps are the ONLY chimps known that dig for roots.

There is a lot more to this story than the Virunga chimps or my work with foragers in the Ituri. There is work by other people on pigs and bears, there is work by my friend Betsy Burr on rodents, and there is information from the fossil record. But the conversation I mention above at DeVore’s house led, after considerable time dicking around with it, to this: The rise of hominids as an adaptive shift in fallback foods: Plant underground storage organs (USOs) and australopith origins. In which:

We propose that a key change in the evolution of hominids from the last common ancestor shared with chimpanzees was the substitution of plant underground storage organs (USOs) for herbaceous vegetation as fallback foods. Four kinds of evidence support this hypothesis: (1) dental and masticatory adaptations of hominids in comparison with the African apes; (2) changes in australopith dentition in the fossil record; (3) paleoecological evidence for the expansion of USO-rich habitats in the late Miocene; and (4) the co-occurrence of hominid fossils with root-eating rodents. We suggest that some of the patterning in the early hominid fossil record, such as the existence of gracile and robust australopiths, may be understood in reference to this adaptive shift in the use of fallback foods. Our hypothesis implicates fallback foods as a critical limiting factor with far-reaching evolutionary effects. This complements the more common focus on adaptations to preferred foods, such as fruit and meat, in hominid evolution.

I don’t think this happened in the Virungas, because as I mention above, they are relatively young volcanoes. It may even be that nothing like this happened at all. The significance of the observation may be simply that chimps can make use of USOs. The last common ancestor of humans and chimps was probably a lot like a chimp. So, the Virunga chimps simply demonstrate that this early population may have been able to use roots for something (water or food) and further demonstrates that the use of this resource could be not only something that some groups use, but that a particular group can survive because of. That is important because of all the interesting things chimps do, like using tools to get termites or various “symbolic” behaviors to communicate, none are done by all groups of chimps, and most or all of these behaviors seem to come and go randomly and do not have a high impact on survival. But the root digging and drinking of the Virugna chimps can’t disappear as a strategy in this one group; They depend on it for survival.

It is also not certain that such a context (a truly dry two months or so per year) requires volcanic sediments, but this does seem like a very likely location for such a thing. A similar thing happens on the Kalahari sand sheet, where water is abundant, but only if you are able to get at the water which is meters, or tens of meters, below the surface. However, I am pretty sure that there is not a huge water-abundant tuber of this type in th Kalahari. But perhaps at one time there was.

Evolving away on the upper slopes of a volcano would have other effects a well. Like, unfortunately, occasional local extinction. Of course, it would also be a great place to “discover” fire … But that is an entirely different story, for another time.

Recent Kenyan Newsreel:

Earlier film on the Nyiragongo volcano (near Nyamuligira) and the region:

LADEN, G., & WRANGHAM, R. (2005). The rise of the hominids as an adaptive shift in fallback foods: Plant underground storage organs (USOs) and australopith origins Journal of Human Evolution, 49 (4), 482-498 DOI: 10.1016/j.jhevol.2005.05.007

A 200-pound chimpanzee kept as a pet and once used in commercials was shot and killed by police Monday after it mauled a woman visiting its owner and later cornered an officer in his cruiser, authorities said.

Stamford police Lt. Richard Conklin said the injured woman was hospitalized late Monday in “very serious” condition at Stamford Hospital; her identity was not immediately released. Conklin said she suffered “a tremendous loss of blood” from serious facial injuries.

source

Much is made of the early use of stone tools by human ancestors. Darwin saw the freeing of the hands ad co-evolving with the use of the hands to make and use tools which co-evolved with the big brain. And that would make the initial appearance of stone tools in the archaeological record a great and momentous thing. However, things did not work out that way.

It turns out that up-rightedness (bipedalism), which would free the hands, evolved in our ancestors a very long time (millions of years) prior to our first record of stone tools. The earliest upright hominids that are definitely human ancestors probably emerged either close to five million years ago or close to seven million years ago, depending on which of the current evidence you like and how you interpret it. The earliest chipped stone tools are a little over 2.5 million years ago.

Furthermore, at that time there was not necessarily any real increase in brain size. Maybe a little in one or two hominid lineages, but it is not clear which hominid lineage(s) were making stone tools in relation to the brain size and the increase in size is unimpressive to the extent that it is probably safe to say that as more fossils are found and more data analyzed it could go away.

It is true that about the same time stone tools show up (give or take a couple/few hundred thousand years) there may have been an increase in species of hominds, and/or an increase in some of the features that they shared, such as whopping big teeth and the skeletal and muscular aparatus to use those teeth. But it is also true, as Alison Brooks and I have shown in various analyses, that it is just as likely if not more likely that the appearance of stone tools in the archaeological record at that point in time is a function of how the arcaheoligcal record is formed. We beleive that it is fairly likely that chipped stone tools were already in use and simply became visible to us at this point. Maybe.

Which brings us to some very serious speculation, but what the heck: I think that what it takes, mentally or neurologically, to make this early, relatively simple stone tool technology is well within the range of capacities I can imagine for a chimp-like hominid. True, modern chimps have a hard time making stone tools, but their “hands” are not “freed” like a more bipedal hominids’ hands would be. The mental/neurological part is not so hard. In a series of experiments some years ago, started by Glynn Isaac, we had many dozen Harvard Undergraduates, who had no prior exposure to stone tool manufacture, bang rocks together (in isolation) for the sole purpose of making sharp edged pieces. All of them managed to replicate most of the products in a typical Oldowan industry in just several minutes. The collection of any dozen or so of these students’ produce includes all of the Oldowan “tool” forms.

The Oldowan is the outcome of breaking rocks.

As to the impact that Oldowan style technology would have on the life of a chimp-like human ancestor? This would probably be as important as any other single aspect of foraging strategy. I imagine they were mainly making sharp edges in order to sharpen sticks, or to cut into things (or both), which would have increased the range of possibilities for accessible foods at the same level that, for instance, cooperative hunting that we see in the Tai chimps of West Africa. Important. Not necessarily overwhelmingly important.

We know the fossil record underestimates diversity at least a little, and we know that forested environments in Africa tend to be underrepresented. Given this, the diversity of Miocene apes may have been rather impressive, because there is a fairly high diversity in what we can assume is a biased record.

But I’d like to make the argument from another angle, that of modern ecological analogues. Let us assume that the greater apparent diversity of apes in the middle and late Miocene compared today can be accurately translated as a modern reduction in ape diversity. Not counting the relatively diverse lesser apes, there are five species (2 chimps, gorilla, human, orang) which can be further divided into 10 subspecies, across the entire old world.

Now look at the size range of all of the living apes. Gibbons are the smallest and gorillas the largest. When a family or subfamily of land mammal is diverse in a particular region (a biome or something larger than a biome) we tend to see that diversity played out along a spectrum of size, and against size we can find additional diversity derived from dietary or subhabitat differences and geography. It seems to me that there is room in the size spectrum between gibbons and chimps, and orangs and gorillas, and there is certainly room above the gorilla size as indicated by the existence in the fossil record of very large Asian forms.

We know that some of the later Miocene apes were bipedal, and it is starting to look like bipedalism or something like bipedalism is showing up among other apes in the Miocene as well. So perhaps there is a spectrum of locomotory pattern along which diversity may be spread.

This gives us a the following size classes: gibbon, siamang, [something in between], chimp, orang, [something in between], goriilla, [something bigger], or at total (a minimum?) of eight size classes across which apes might exist in a world in which apes are divers. Like the Miocene. If we add to this a more arboral form and a more bipedal form, perhaps we double the number, or perhaps we add about five new classes (I’m guessing that a Mighty Joe Young size ape would not have been bipedal!). This gives us about a dozen, conservatively estimated, niches when we divvy up size and so-called positional behavior.

To this we can add geography. It is probably reasonable to assume that a wetter, more forested middle and late Miocene Africa could be divided into at least four or regions, between the West/Central divide that modern biogeogrpahy tells us was effective at least in the Late Miocene, the Congo River divide, North/Central Africa, East Africa and Southern Africa. Let’s conservatively assume four, and let’s assume that only half (six) of the hypothesized ape species are divided among these areas. That means that 24 species are endemic to varoius regions, and six additional species are more widely spread for a conservative estimate of 30 species.

Among these species there may have been several bipedal forms, but only one of them (plus or minus a little hybridization hanky panky here and there) would have been the human ancestor. Of course, no one at the time suspected that …. (Or they probably would have done something about it.)

This is not an outrageous suggestion. The idea that if you went back in time to a more ape-rich time (and we know it was more ape-rich) and got a current copy of the Guide to the Mammals of Africa, the ape section would have a few dozen species, just like the monkey section or the antelope section today has a few dozen species.

Go apes!

The world’s rarest great ape has found a safe haven in the mountains of the west central African nation of Cameroon. With guidance from the Wildlife Conservation Society (WCS), Cameroon’s prime minister, Ephraim Inoni, has created the world’s first sanctuary exclusively for the Cross River gorilla.Kagwene Gorilla Sanctuary spans only 19.5 square kilometers but contains an important segment of the Cross River gorilla population. The species’ range consists of 11 scattered sites in Cameroon and Nigeria. Of the estimated 300 or fewer Cross River gorillas that remain, approximately 20 live in the new reserve.”The creation of this sanctuary is the fruit of many years of work in helping to protect the world’s rarest gorilla subspecies,” says Dr. Roger Fotso, director of WCS-Cameroon. Fotso and his colleagues worked in tandem with the Cameroon Ministry of Forestry and Wildlife in laying the groundwork for the sanctuary.

The rest of the details are here.I am not personally convinced that this is the rarest population of great apes. The most threatened are certainly the eastern lowland gorillas of the Congo, of which there may be only a handful left. If any.