Despite tens or hundreds of thousands of years of very strong Natural Selection, wildebeest do not arrive at the Mara River with a genetically determined brain mechanism or module that helps (much) to keep them from being eaten by the crocodiles that live in the river. Most of the wildebeest that try to cross the Mara in the annual migration have never seen a croc, or a river, before in their lives, or have encountered this situation only once. This would be a very good situation in which to evolved such a mechanism.
Where is evolutionary psychology when you really need it?
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Would it even be adaptive not to have a number of animals eaten by crocodiles or would populations become too large when not kept in check this way?
“999 trillion millenia from now they will still be wildabeests” Now that’s physically impossible!!
Hooray for stupid commenters.
Where would the internet be without the disgustingly ill-informed?
There would have to be some sort of behavioral tendency that increased their chances of survival. An obvious one is not the be the first to head out into the river. I imagine no one want to be first and that they mill around and mill around and maybe eventually kick some poor weakling out there to become the first meal. If that is true that is certainly evolutionary psychology.
Is there a concerted campaign here? I see a bunch of posts on different blogs all anti-evolution. All posted from names that are short phrases of Latin derived English words. All slightly snarky and almost parody-like. Either a joker troll or somebody has decided to DO something about evolution.
PAI@6:
FIFY.
Well, maybe they DO have such a behavioral adaptation. If you are a wildebeest, your best chance of getting across the river alive is to mass together with the rest of the herd and all cross at once; the crocodiles can only eat so many of you.
PAI@9:
Fixed
It
For
You
Generally used as a bit of snark after someone takes a prior statement from a dim-witted poster and edits it in such a way as to improve the accuracy.
As everyone can now see, you are not only ignorant of science but Internet convention. It is perhaps time for you to return to playing with your GI Joes.
“I have the solution, but it only works in the case of spherical wildebeests in a vacuum.”
@ PAoI:
~ 10^18 years is much longer than the expected remaining lifetime of the biosphere. (~ 2-5*10^8 years before our warming main series sun will make erosion bind up too much carbon dioxide for plant to photosynthesize.)
I like it how creationists maintain the impossible observation that their children looks exactly like clones of their parents. Or we have genetic change, in which case there are no boundaries.
Evolution is the best observed fact in all of nature due to its complexity, and I say that as a PhD in physics. For example, famously Universal Common Ancestry of all cells have a 10^-2040 risk of being the wrong observation.
Creationists with their spontaneous “poof” of cells are even worse out, since any of their poofed organisms would have some 10^24 atoms randomly combined (if they weigh 10 kg on average), or a 1:10^24! chance.
Since already 10^70 ~ 10^100 is larger than the number of atoms in the observable universe ~ 10^90, we see that they believe in random luck and innumerable multiverses over a simple process of variation and selection that can happen on any habitable planet.
Speaking of which, I was just looking through Ellis’ contribution to the recent FQXi conference on time. He noted that what makes the universal time advance, locally quantum mechanics decoherence, is unavoidably a process of macroscale selection of “interesting features” which is that confer increasing entropy.
He, and several with him, saw that arrow of time process move all the way up to biological evolution. Time is what makes the universe go from quantum through nucleosynthesis through chemical to biological evolution.
Also in this context, humorously the conference noted on complexity that “only creationists” mistakes it for entropy. In complexity theory such measures max out for intermediate scales, and indeed standard cosmology have complexity maximize and then vanish at ~ 10^100 years when the last black holes evaporates.
Oops, I mistook Avogadro’s number. It is more like 10^27 atoms that creationists claim poofs out of 10^27! permutations. Some 10^8 times for all species, in perhaps 10^7 years – or at once, if you are a creationist.
GL — “very strong Natural Selection”
Has anyone ever attempted to quantify this? I wonder how strong this particular selection really is, compared to all the other losses in migration — including just drowning while while trying to swim across rivers? How many do the crocs get in a given year, vs. the lions and hyaenas on the plains? These herds are huge — how many crocs are even in the river and how many gnus can/will a croc kill in a day? 1 per croc/day? While dramatic, is it possible that croc damage to any particular herd is relatively insignificant? What are the chances of any given gnu dying of croc bite, versus threat X?
Also, what possible behavioral defenses are there, besides crossing en mass? That approach has significant costs of its own, as animals get tangled up and drown each other, so maybe the relative benefit of mass crossing is not all that great. Maybe rivers are just a permanent problem, hard to evolve your way out of if there’s a simultaneous need/benefit to maintaining and improving the other traits of a migrating plains quadruped. If the costs of some potential solution are not significantly less than the benefits, how can selection act?
Pondering creationist options, one wonders why the allegedly benevolent God didn’t just give the gnus the ability to run across the water surface, like he allegedly did for his “son” and as he presumably did for the Jesus lizard. Or, dare we imagine gnus pattering across the water surface like storm petrels? God being “omnipotent” could do that, theists imagine. God must not care about the suffering of these wildebeasts, even though he supposedly made so many of them. Heck, why’d he even make those monstrous crocs in the first place? It’s true that the only decent excuse for God is that he does not exist. He’s not there to blame.
PAI: Because in the beginning crocodiles were plant eaters.
Evidence? Why do they have those funny pointy teeth?
PAI: All animals were plant eaters.
Evidence? Even the animals totally incapable of digesting plant tissue and those with intestines too short to use it efficiently?
PAI: Humans were plant eaters.
Evidence that early people were exclusively vegetarian?
PAI: It wasn’t until AFTER sin entered into the world that creation was changed and the world became violent and full of death.
So how did the eating of an apple by two mythical people make crocs so mean? Please present actual evidence, not made-up stories.
Why do you think your God is so incompetent that his plans were easily defeated? Or did he plan for the world to become violent and full of death? If he’s all powerful and doesn’t want violence, why hasn’t he stopped it?
PAI: In the beginning it was a perfect place.
But God planned poorly, so that didn’t last. That’s your view?
PAI: Evilution had nothing to do with it since evolution is a myth.
Jesus is a myth. Evolution is observed. You can see it yourself, if you’d just open your eyes and go outdoors.
arch, the causes of death of the serengetti gnu are pretty well documented. I can’t lay my hands on it right now but I will.
PAI, it’s sure that Christians have no evidence to tout for any of their beliefs, as shown most recently by your running away from a chance to show any you might have. If you want to see evidence for evolution you can start with “The Origin of Species” by Charles Darwin. I’m sure you’ve heard of it, but I’m equally sure you’ve never read it. Ignorance is the single essential basis for creationism.
The dishonesty of Christians is so conspicuous. They pretend to think the evidence of evolution is too weak, yet are rigidly certain that Jesus was real, even though that contention is supported by at best 2-3 weak points (possible facts), while the theory of evolution is supported by literally hundreds of millions of hard verifiable facts from all scientific disciplines. Of course, the evidence that Jesus was a magic man/god is supported by no evidence at all. There’s a thin chance that he existed as a regular human being, but probably not. We have the bones of Lucy, and hundreds of other near-human beings, while for God and Jesus you have nothing but old contradictory stories. Jesus probably has no more historical reality than Thor, while fossils representing possible human ancestors have been found in such numbers that it’s become hard to know which one is closest to the line leading to us. We have an embarrassment of riches, and Christians have nothing but “faith”.
How old do you think the Earth is, BTW? Are you one of those 6-10,000 year types? I’m guessing you are.
GL — the causes of death of the serengetti gnu are pretty well documented. I can’t lay my hands on it right now but I will.
Thanks. I don’t have more than a general biologists knowledge of gnus (maybe less, since I’m really a botanist). I’ve only seen them at the zoo. I figured you’d know where to find something more.
And I apologize for getting off topic by responding to PAI’s tripe. I’ll try to stick to the issue better. The ignorant arrogance of these folks sometimes sets me off. Sorry.
As a small pastured livestock farmer, I am greatly interested in the ideas of Allan Savory (2010 Buckminster Fuller prize winner), which involves a third player – grasslands – in the herd/predator dynamic being played out here.
Contrasting fenced, protected livestock raising systems with the natural ecosystem of herd beast, predator and grasslands, he is fascinated by the effects on the grasslands themselves when herds are kept tightly bunched (also continuously on the move) in their foraging journeys by the ever-present threat of predators. This results in grasslands receiving three important herbivourous impacts at the same time – 1) grazing 2) manuring and 3) heavy footfall mixing of manure, grassroots and soil. And then (since the herd must remain on the move) a substantial rest period which allows the grassland to recover and, in fact, thrive.
Domestic livestock, by contrast, being protected from predators, and also not so free to move because of territorial fencing, do not behave in the same way, and do not therefore benefit grasslands in the same way, leading to grassland detriment and desertification.
By incorporating practices that replicate the effects of predators as much as possible in the planning of domestic herd movements, Savory has demonstrated that it is possible to reverse desertification while also increasing the domestic herd size, and most importantly enhance local biodiversity and wildlife survival.
I agree that herd crowding behaviour IS the major adaptation being followed by the gnu here, but this behaviour appears not only to benefit the herd (although some individuals do lose out each time), but also their source of nutrition, the grasslands.
Why oh why are you all feeding the troll. Whether real or fake, you are only entertaining him or her. Trolls are like reality stars, if you ignore them, they go away.
Trolls? We have no trolls, just a buffoon or two. They’re different beasts.
“All posted from names that are short phrases of Latin derived English words.”
That sounds like mine to me..
Didn’t intend an anti-evo-pun though!
At most I was openly wondering; if this is a K-species, the mere adaptation could be in high numbers which -in turn- might offset future reproduction and survival if not balanced at that moment.
The total lifetime predation of Serengeti wildebeest by crocs is a least 1%, possibly 2 or 3%, of the total predation caused death, concentrated during the water crossings during migration.
Serengeti Wildebeest die mainly from either starvation or predation, with lack of food being the larger factor (probably) all the time, and the relative role of predation depending on the usual dynamics of predator/prey demographics, etc. (Not directly related to the reasoning here but interesting: About half of the wildebeest that die in a give year, at least among adults, die during the migration).
The main predator is lion. Of all the predators, Crocodiles eat about 1% of the predated wildebeest, and they are the lowest ranked. However, much of that predation (by animals like jackels) is of 1-4 month old animals, and during the river/lake crossings, there are none of those, so these numbers shift. In other words, removing the “infant mortality” (as it were) factor, the number of wildebeest killed by predation by crocs, as a function of total killed by predation, probably goes up to 2 or even 3%. Also, mortality is estimated by carcass counts, and crocodiles do not leave countable carcasses much of the time. (This is underscored by examining Mduma’s extensive and detailed study, which records zero croc predation because the methods don’t allow it to be counted at all.)
The chance of becoming a “yearling” as a wildebeest is very low, between 20 and 40 percent, so starvation, predation, etc. has taken much of it’s toll prior to the migration from the point of view of the wildebeest born in a given year. This further sharpens the importance of crocs for those particular animals.
So most wildebeest dies of starvation, of the rest, predation by large predators (lions, leopards, hyenas, etc.) is the largest cause of natural death, with crocs averaging out at about 1%
However, at the age wildebeests experience their first migration, and thus their first encounter with crocs in the water, is when much of that lifetime croc predation occurs 1% is already enough to consider strong selection, but if all of that is concentrated in a reliable annual event over a short period of time, one would expect it to really matter.
There are places where wildebeests actually cross lakes, with crocs in them, where they could easily walk around the lake, but don’t. There isn’t even an “avoid water because there might be crocs in there” mechanism.
I’m sure there are adaptations that are relevant, but they are more generalized … sight, olfaction, hearing, speed, kicking, stotting, running, alarm calling, having horns and knowing how to use them, etc. etc. Which is exactly what a Darwinian model of evolution would expect. An evolutionary psychology model, on the other and, would predict a set of brain modules for various kinds of situations … a cat avoidance, hyenid avoidance, croc avoidance, etc. mechanism. But it appears that these brain modules have not emerged in the Serengeti wildebeests.
Mduma, Sinclair, Hilborn. 2001. Food regulates the Serengit wildebeest: a 40-year record. Journal of ankmal ecology 68:6
Mills and Shenk, 1992. Predator-prey relatoiships: the impact of lion prediation on wildebeest and zebra populations. Journal of animal eclogy 61:693-702
Owen-Smit and Mills 2007. Predator-prey size relatoiships in an African large-mammal food web. Journal of animal ecology 77:1
Sinclair et al The Serengeti Ecosystem
Gereta, Wolanski, Chiombola/. 2003. Assessment of the environmental, social and economic impacts on the serengeti ecosystem… Frankfurt Zool. Society.
Nice summary!
But aren’t most of these general adaptations more effective in warding off land predators than crocoldiles?
Yes, but I should also mention that wildebeests are afraid to go in water. They seem to have no particular adaptations to detecting specific dangers (i.e. crocs or large snakes) in water, or distinguishing bodies of water with crocs in them, or an alarm call that is croc specific (as far as I know, though I’d have to verify that).
That last comment added a lot more nuance and detail to the OP, Greg. Fascinating – thank you.
Yeah, the OP started out as a facebook status but became a post. Now, the post with the comments together re-written can be a newer updated post, perhaps with a touch of “Peer Reviewed Research Blogging” and a couple of images thrown in. Hell, I can probably work a book review in there.
You’ve found some of the best references to predation risks already, but I have to admit I think the 1% estimate is likely to be a vast overestimate (Simon’s 0 is probably closer!)
Look at it from the predation end: I’ve not found concrete population estimates for the Mara River, but densities aren’t too high – this top record for the river CITES has a maximum estimate of just over 2/km. My casual observations would suggest that’s about right for the regions inside Serengeti/Mara – about 70km of river = 140 animals. Assuming all these are big enough to eat Wildebeest, and they each eat one every three days whilst the animals are in the region (late July – early Nov, say 120 days), which I think is a huge overestimate, between them they eat 5600 animals per year. In a population of 1.2M, that’s pretty close to 0%! Now, let’s allow for the fact there’s a slightly smaller population on the Grumeti River too, and the animals are there for only 3 weeks, and we still are struggling to get close to a significant source of mortality. Yes the animals sometimes cross lakes – but Lake Ndutu has a total croc population of 1. And it’s a small one… Drowning must be a far, far more important source of mortality when the rivers are high (as last season).
Now that said, these animals really do show massive fear when approaching water either to cross or to drink – they know there’s a risk. But what sort of response would you expect them to evolve? When I’m crossing water with crocs in it (I prefer to do it in a car, but sometimes you’ve just got to check on foot first) I stop and look for a long time and try and spot them, but it’s very tricky. Then I’ll look for a shallow place to cross where there’s little chance of getting rolled if one is there. And then I go like crazy! Unfortunately I’m not usually in a position to take a few 1000 friends with me, but I’d be much happier if I were. And these are exactly the same things you see wildebeest looking for when they come to drink / cross the river. In fact you sometimes see crossing happening after many hours of indecision when one does indeed lose it’s footing at the river edge and then the rest follow. What else can they do to minimise their predation risk? You have to drink or you’ll die, and you’ve got to cross the river or you’ll run out of food. They also respond like lightning when drinking if there’s any sign of the water moving.
BTW to talk of losses happening ‘during the migration’ is somewhat strange – the migration is essentially a more or less continuous process, even during the two longer stays in a region (dry season near the Mara, wet season for calving) the herds are seldom in the same place for more than 3 days before moving on – that number of animals simply has to keep moving to find food. (I posted a blog reviewing the factors driving the migration in Serengeti recently, if anyone’s interested: Great Migration)
Evolutionaries always tout their “evidence” but I have yet to see their evidence.
Well, yeah, you have to get your head out of your ass, otherwise all you’ll ever see is shit.
Greg: “An evolutionary psychology model, on the other and, would predict a set of brain modules for various kinds of situations … a cat avoidance, hyenid avoidance, croc avoidance, etc. mechanism. But it appears that these brain modules have not emerged in the Serengeti wildebeests.”
Can I quibble with you on that? The quibble(s) may simply demonstrate that you have a better understanding of how environmental pressures drive selection of specific characteristics and functions than I do, but here goes.
Since a wildebeest encounters a variety of predators in a variety of landscapes, maybe a generic avoidance response is more effective for the species as a whole. One possibility may be that predator specific avoidance mechanisms have developed in individuals or family groups, but the cost of that adaptation is greater vulnerability to other threats–
for example, a mental module for targeting the visual and auditory cues that would tip-off the presence of a croc in the water might require sight and hearing (in the broad sense of processing visual and auditory stimuli and making useful interpretations of the stimuli) that would be less well suited to identifying lions moving in the grass; over time, maybe generic avoidance triggered by noticing the wildebeest next to you being dragged underwater by a croc is simply effective ‘enough’ for the species, and specific predator avoidance doesn’t produce enough of an advantage to be refined and elaborated over time.
Second quibble– what if predator specific mental avoidance modules are present to some degree, but we haven’t yet made observations that are sophisticated enough to document them– we just see the poor sap wildebeest that gets munched– do we track individuals and family lines over enough successive migrations to determine if some wildebeest lines are more adept at navigating crocs in the rivers, others evading lions, and so forth, and the jury is still out which will be the dominant wildebeest type 500,000 years from now?
Last quibble– what degree/ type of cognitive activity are prerequisites for the development of ‘mental modules’? Do wildebeests have such cognitive functions? On that note, this article gives a nice description and overview of evolutionary psychology:
http://bernard.pitzer.edu/~dmoore/psych199s03articles/bjorklund.pdf
“Tooby and Cosmides (1992) have argued that complex psychological mechanisms evolve only under circumstances when the environments are relatively stable over many generations. Thus, over long periods of time, members of a species could ‘expect’ certain types of environments, and they evolved species-typical solutions to deal with such stable environments.” (pg. 1691)
Over a varied landscape with both land and aquatic predators, maybe generic avoidance trumps specificity.
Just spit-ballin, Serengeti wildebeests aren’t common in Philadelphia.
Regarding the last point first: T&C and I have argued about this for years. I’ll tell you an anecdote. Excavating a 2my a site in Africa, looking for hominids, all I could ever find were wildebeest. Had I found a hominid (and hominds have been found in this site) it would have been way way different from modern humans. Hominids are the species that has lived short term in diverse environments (not amenable to the long term context for selection for C&T type modules) while the wildebeest have been.
Regarding your first point, I agree, and that’s how cognitive evolution may work, and it’s not EP type modules.
Regarding your point about “do wildebeest have this capacity” … well, there, you’ve uncovered my little plot, haven’t you! One could conclude at this point that they don’t. Perhpas C&T type EP modules are a primate thing, or an ape thing.
I would be happy to provisionally conclude the following:
Antelopes are unlikely to evolve problem specific modules. This may also be unlikely in other orders of mammals, possibly most.
and
It remains to be seen if they emerge in primates, or apes, or humans, but we can leave it on the table as a possibly.
If any evolutionary psychologists in the room would like to agree with that, I’d be happy. But be wary. Calm waters sometimes cover …. Oh, never mind, you’ll see.
Greg, thank you very much for for expanding on this. I apologize for not responding promptly, but my schedule this week has been hectic.
The discussion has become very interesting and I’d like to go into a few issues, but only one of them today.
At one point you said that there were places where wildebeasts would swim across lakes with crocs, even though they could go around. But later you said: “Yes, but I should also mention that wildebeests are afraid to go in water.”
Is it that some populations are more afraid of water than others? It would seem that swimming avoidance could be some sort of generalized defense against crocs, drowning, flukes, and maybe other things. Are those that will swim across lakes ones in areas where the water based threats are just less? Crocs are there, but few?
I don’t even know if gnus are broken into sufficiently isolated populations that behavioral differences in this respect could have developed. Could it just be a herd-sticking-together thing? If the lead gnu plunges into the lake they all follow, and some years that happens, but some years the lead gnu is a water-dreader and decides to go around the lake instead? I would think there’d be a lot of drownings in a large lake, regardless of any crocs.
Maybe I’m close to advocating evolutionary psychology here — since I don’t work on animals I’m not really familiar with the literature on the distinction between general predator/danger avoidance behavior and the more specific sort that evo. psych. apparently advocates. Would behavioral differentiation of populations be possible, as I assume?
I think they are all afraid initially, and it takes them way longer to wade across the lakes than it would to walk around them, because they refuse to go in, but end up being pushed in by those following behind. It does not matter if the lakes have crocs in them or not (they often don’t)
I don’t even know if gnus are broken into sufficiently isolated populations that behavioral differences in this respect could have developed.
Not the ones in the Serengeti but there are many populations around Africa (often with their own migratory systems) and there is plenty of room for variation among them. Unfortunately the kind of data you would need to make the comparisons is lacking, but it is a great potential study.
I can tell you that predator avoidance practices for black and blue wildebeests are basically the same (overall similar set of strategies) but seem to be different in detail. They are two different species, but closely related.
Did I say something wrong – it was rather long for a comment I admit? Or did my post just go AWOL? It certainly seemed more on topic than some comments, but I’ve no copy of it ‘m afraid. If you’ve still got it and think there’s anything in there that’s valid, please feel free to edit out what’s not.
Colin, I don’t see your comment … still looking. We’ve had some tech troubles. I hope it wasn’t lost.
… brb …
OK, found it. Something has changed to cause some comments to go to a strange place.
I hope to actually read it soon. Thanks for letting me know it was stuck!
Greg: “Hominids are the species that has lived short term in diverse environments (not amenable to the long term context for selection for C&T type modules)â?¦
Antelopes are unlikely to evolve problem specific modules. This may also be unlikely in other orders of mammals, possibly mostâ?¦
It remains to be seen if they emerge in primates, or apes, or humans, but we can leave it on the table as a possibly.”
My next quibbles arenâ??t with you, theyâ??re more with evo. psych. in general. My early exposure to evo. psych. left a somewhat sour taste, since what little I read then seemed to be a repackaging of gender role stereotypes in fancy cognitive science and evolutionary theory terminology (q.v. Buss, in all his glory, nicely dismantled here: http://digilib.bc.edu/reserves/ps531/tami/ps53107.pdf).
I take it as self-evident that our brains are products of evolution, and so brain functions, such as cognition, are products of evolution as well. I not sure that weâ??ve established too much beyond that. Which cognitive processes can we state confidently are problem specific adaptations to early hominid environments? There I waver a bit.
For example, auditory stimulus discrimination and recognition is a pretty common cognitive function in mammals â??is that a predator, the wind, a swarm of insects, a luxury safari tour group in Land Rovers, etc.?
Letâ??s refine it a bit. Is that John Coltrane, the Sex Pistols, or the high school marching band? Also auditory stimulus discrimination and recognition. How problem specific is it?
As is often the case, Iâ??ll go off on a tangent.
The language of cognitive modules is laden with the analogy to computer processors, and evo. psych.â??s seem especially enamored of the metaphor of computer processors (and parallel processing, and algorithms, etc.) to describe cognitive processes. This reminded me of a great essay by John Daugmanâ??â??Brain Metaphor and Brain Theoryâ??:
http://www.cl.cam.ac.uk/~jgd1000/metaphors.pdf
â??â?¦perhaps nowhere else in the history of ideas has there been a more striking patter of reliance on metaphors than in the history of reflection about the brain and the causes of behavior, and about the enigmatic relationship anong brain, mental life, and personhoodâ? (pg. 23).
The key bit for this conversation:
â??At its core, the computational metaphor of brain function invokes the notion of formal rules for the manipulation of symbols, as well as certain ideas about data structures for representing information. Surprisingly, given the pervasive popularity of this metaphor, there remains today no well-established evidence of symbolic manipulation or formal logical rules at the neurobiological level in animal physiologyâ?. (pg. 31)
Iâ??d characterize â??modulesâ??, and even â??modularityâ?? as variants of â??data structuresâ?? and â??formal logical rulesâ??, and as such, reified metaphors.
We can get hung up debating whether they are â??domain/problem/species specificâ?? or not, when such modules exist only as conceptual markers for the presumed neurocognitive substrate for observed behaviorsâ??something in the brain, or some product of brain processes must produce the observed behavioral patterns. Saying, with specificity, that it is a stable neuropsychological process (module) that was selected for in ancestral environmentsâ??I think that sort of evo. psych. claim has less substance than assumptions about existence of a Higgs boson, and no credible way to test the claim as yet.
I agree.
I really appreciated Colin’s comments on croc density and the link to his Great Migration website. I recommend following that link to any other generalists interested in better understanding the East African animal migrations. I had no idea about the nutritional complexities, for example.
I have decided that crocs are a dramatic source of mortality to wildebeasts, hence of footage in nature videos, but they are probably not an important source of mortality. There are apparently just not enough crocs.
Colin, sorry, I missed your comment until just now; Good point about the number of crocs. The 1% estimate is still based on data, though, so I’m not ready to give it up just yet. Let’s just say it is subject to revision.
“Now that said, these animals really do show massive fear when approaching water either to cross or to drink – they know there’s a risk. But what sort of response would you expect them to evolve? ”
A two part answer: 1) I’d expect them to evolve generalized fear mechanisms, herding, etc. which they have evolved, and which conforms with expectations based on a traditional Darwinian model of evolution of senses, emotions, and responses in mammals. 2) If they were going to be able to have a finely tuned mechanism vis-a-vs an evolutionary psychology model, well, to be a real evolutionary psychologist I’d first see what they had evolved and then claim that as what I expected …. but since I’m not, what I’d want to see minimally is the ability to assess whether or not crocs are present and to act accordignly (i.e, going around the water if possible, or adjusting vigilance based on what they observe)
“BTW to talk of losses happening ‘during the migration’ is somewhat strange – the migration is essentially a more or less continuous process, ”
Some sources do that, and yes it is a bit strange. I’m not entirely sure it’s relevant and it did not make a lot of sense.
People often do have differing ideas on what the migrationlooks like. When I’ve had tourists in the Serengeti (as a guide) I would tell them on day one “I’ll show you the migration tomorrow” then the next day we woulds see some zebras and wildebeest and I’d say “see those? They’re different than the ones that were in that exact spot yesterday. Migration!” (Or, “See those guys way over there? They were way over THERE (pointing the other way) when we arrived yesterday afternoon)
You can get a Hollywood style migration going with a helicopter but it is normally not allowed.
Greg: OK, I’m now interested in finding these data. I had a quick look at the citations you’ve given and find that the Mduma paper is well known and as you say, no crocodile mortality. Milles and Shenk is based on Kruger data, as is the Owen-Smit paper. Tony’s books on Serengeti (there’s none with your title, but I briefly searched all three Serengeti books) have nothing beyond a population estimate in them (lower than my inferred population, btw) and the Gereta et al report doesn’t help here either. I did my own little search and couldn’t find any papers that might help. Can you point me in the right direction?
Otherwise, I have to confess I’m not familiar enough with EP to understand when an argument is traditional Darwinian and when you might call it EP. They certainly don’t cross in places where crocs are obvious though – the problem is that not all of them are ever obvious, even to 1000s of eyes, and they can only go a certain distance away from one obvious croc before they come to another obvious croc, and they can’t possibly be expected to spot all crocs anyway. It’s even more striking when they come to drink at a waterhole where they know there are crocodiles (and lions) – beyond not being the first to drink, there’s no real choice: pick your drinking site as far from obvious crocs as possible, pick a site with very shallow water where they’re going to be more obvious as they come to attack, take lots of friends with you, try not to be first there (probably not too important, from my observation), drink as fast as possible, have an amazingly quick response to anything surprising. EP or not, I really can’t think what better approach is possible – you certainly can’t put off drinking for ever.
The EP argument is different from the standard evolutionary argument in a very important way, and that is the point of this post, so I’ll make it more explicity.
According to Darwinian psychology, (traditional) various behavioral capacities that are known to exist (the usual flight-fight mechanisms, fear, sensory processing, etc.) in mammals are generalized mechanisms that are fine tuned by natural selection to be more appropriately responsive to the environment the organism has been busy evolving in. So medium to large ungulates run while small ones hide given similar situations, for example. There is co-evolution between the brain, the rest of the nervous system, and the various sensory or other parts, and this all predisposes an organism to develop appropriate behaviors. Generalized mechanisms are fine tuned only to some extent by selection and then more refined during life with experience.
EP is about humans and not mammals in general, but EP often cites animal behavior generally, usually mammal behavior, either generalized (which is dangerous) or specific cherry picked species of interest, as models. That’s will be relevant later.
OK, you can imagine that generlized behaviors together with fairly specific experience might cause the development of an individual’s brain to be good at a certain thing. A person who spends a lot of time living on the Serengeti and perhaps even had a mentor would eventually know where to drive their Land Rover at the end of the day to have a good camping spot based on how the terrain looks. The camping spot would have certain characteristics that would enhance survival. By the way, since Australopithecus and friends in South Africa are known to have been found in caves that were near tree stands in an otherwise grassy area, EPists believe that a place with a few trees surrounded by an expanse of grassland is a good camping spot in the Serengeti. But I digress
Anyway, the ability to think through a problem can emerge in an individual from a combination of innate capacity and experience. The soccer coach is good at soccer strategy, the race car driver is good at racing in a car, an accountant is good at managing the books, an experienced file clerk is good at filing things efficiently and an experienced bartender is good at guessing when a potential customer is lying about his or her age.
EP simply specifies that these abilities are supported by task-specific brain mechanisms that are called modules, that exist mainly in the cortex but make use of other brain regions; That these modules emerge in normal individuals because they are specified by genes; and that these genetic systems that specify the modules are shaped and fine tuned in detail by natural selection, which occurs over a period of time called the “Environment of evolutionary adaptedness”; They also further specify and hang tenaciously to the concept that the EEA for humans is 2 million years long, looks like the main grasslands of the Serengeti, and was inhabited by australopithecenes and other hominids that acted on a day to day basis like the Ju/’hoansi Bushmen of the Kalahari studied by Lee and DeVore.
I’m not making any of this up.
Therfore, they say and have data to back it up, if you give a bunch of unintiated undergraduates (and I’ve done this experiment myself a dozen times with thousands of students, and it really does work) a certain test you can prove it. The test is a logical test where they must observe a simple logical problem and provide a simple logical answer. When the test is couched in terms of file clerking (you are a file clerk, you took a vacation, while you were gone a temporary worker fucked up your files, so you’ve got these five files on your desk and you need to inspect the smallest number of files to figure out what is wrong, which files do you look in?) the students do very poorly. Our species were not file clerks in the EEA so we do not have an evolved brain mechanism for figuring out files. Alternatively, the students are given a test whereby you are a bartender and five people are sitting at a table and have ordered various drinks, some alcoholic, some not. You have to ask the minimum number of customers for their ID, who do you ask? This question is answered redily and easily and with a high rate of correct answers by the sample of students given that problem. This is becuase in the EEA, we were all bartenders … no, wait, … we were all living in social settings (of bushmen on the Serengeti) and we needed to know who was telling the truth vs. who was telling lies in order to have higher RS. Etc.
I no longer think the crocodile argument I was trying to make can be made (at this time). Too messy, not enough information. But what I was TRYING to do is this:
I was thinking that if mammals in general had modules, then Wildebeest would have a croc module. But it seems that they don’t have a croc module. Since they should have one but don’t that’s a single nail in a medium sized coffin suggesting that ungulates don’t have brains with modules. Many evolutoinary psychologists would respond that it does not matter, because only primate brains have the expanded cortext for these modules to live in, especailly apes, especially humans because the modules must live in the forebrain which is very large in humans.
Then, of course, we have a problem, because a very large range of supposed human behaviors adapted as modules in the brain are defined by EPs and the nature and character of these behaviors are taken from animal models across the board, but mostly mammal, some primate, but among the non-primates, many ungulates (but also pinnepeds). For example, male humans are supposed to act like male elehpant seals, red deer, or bison, in their approach to society. I personally have no problem with a generalized model of male vs. female mammal behavior given internal fertilization and lactation, but such a model is limited. What I’d like to do if possible is to simply cut out the non-ape models entirely, though, when it comes to evolved modules. That’s part 1
Part 2 is this: We know a fair amount about how the neural circuitry of the expanded frontal regions develops, and the main thing we know is that it develops and hooks up not in relation to some underlying complex coding that could possibly produce EP style modules, but rather, in response to the development of the rest of he cortex. It is simply not possible to specify how EP modules would emerge developmentally in human frontal cortex. In other words, they can’t so they certainly don’t. So if a comparative model drives the modules into the frontal region, then there they will die the ugly death of a pretty hypotheses being speared to death my a phalanx of ugly facts. Or perhaps in this case it is a monstrous hypothesis being run to ground by a troop of beautiful facts. Either way ….
Ah, thanks for taking the time to spell it out for me! I’ll have to think some more about whether thinking this way can really help give useful insights or not – but for now it looks like a bit of an idea taken to it’s (logical?) extreme goes a bit crazy…
(I do like the ideas that we were all bar tenders on the Serengeti once, though. But I doubt it – I’ve been involved in teaching folk out here to mix sundowners and can assure you it doesn’t come naturally (Red wine by the shot was the best I think!))
On a tangential topic: Greg, do you have plans to work-up your African diaries into a book? Seems like you’re a good part of the way there with what you have online now.
Ahhh… Sundowners. The ultimate mixed drink, and it doesn’t matter much what you are drinking.
What I find interesting about the Serengeti model is this: Think about what the “classic” Serengeti looks like … say between Mbuzi Mawe and the southern plains, or north to the Mara where there are open plains dotted with occasional trees etc. etc. (the image in the minds of the evolutionary psychologists) compared to other areas, say to the west, where things can be more hilly and there is more forest and woodland (not so much in their minds). THen think about where the primates, primarily baboons and vervets, are. Those big grassy plains with the antelope and zebra, under the constant watchful eye of sleeping lions, is not primate country. I doubt it would be hominid country, untill much later; Food, water, shelter, coverage while traversing the landscape, smaller game, and scavenging opportunities not already monopolized by superpredators would put hominids in habitats OTHER than the classic open plains.
The problem is most EPs have spent no time in Africa, or if any, they visted Nairobi Game Park and Serengeti and otherwise are mainly working off impressions. It would be like trying to understand US culture by only watching CSI tv shows.
Achrachno: Thanks, working on it!